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Abbott JR, Jeakle EN, Haghighi P, Usoro JO, Sturgill BS, Wu Y, Geramifard N, Radhakrishna R, Patnaik S, Nakajima S, Hess J, Mehmood Y, Devata V, Vijayakumar G, Sood A, Doan Thai TT, Dogra K, Hernandez-Reynoso AG, Pancrazio JJ, Cogan SF. Planar amorphous silicon carbide microelectrode arrays for chronic recording in rat motor cortex. Biomaterials 2024; 308:122543. [PMID: 38547834 DOI: 10.1016/j.biomaterials.2024.122543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 03/05/2024] [Accepted: 03/19/2024] [Indexed: 04/21/2024]
Abstract
Chronic implantation of intracortical microelectrode arrays (MEAs) capable of recording from individual neurons can be used for the development of brain-machine interfaces. However, these devices show reduced recording capabilities under chronic conditions due, at least in part, to the brain's foreign body response (FBR). This creates a need for MEAs that can minimize the FBR to possibly enable long-term recording. A potential approach to reduce the FBR is the use of MEAs with reduced cross-sectional geometries. Here, we fabricated 4-shank amorphous silicon carbide (a-SiC) MEAs and implanted them into the motor cortex of seven female Sprague-Dawley rats. Each a-SiC MEA shank was 8 μm thick by 20 μm wide and had sixteen sputtered iridium oxide film (SIROF) electrodes (4 per shank). A-SiC was chosen as the fabrication base for its high chemical stability, good electrical insulation properties, and amenability to thin film fabrication. Electrochemical analysis and neural recordings were performed weekly for 4 months. MEAs were characterized pre-implantation in buffered saline and in vivo using electrochemical impedance spectroscopy and cyclic voltammetry at 50 mV/s and 50,000 mV/s. Neural recordings were analyzed for single unit activity. At the end of the study, animals were sacrificed for immunohistochemical analysis. We observed statistically significant, but small, increases in 1 and 30 kHz impedance values and 50,000 mV/s charge storage capacity over the 16-week implantation period. Slow sweep 50 mV/s CV and 1 Hz impedance did not significantly change over time. Impedance values increased from 11.6 MΩ to 13.5 MΩ at 1 Hz, 1.2 MΩ-2.9 MΩ at 1 kHz, and 0.11 MΩ-0.13 MΩ at 30 kHz over 16 weeks. The median charge storage capacity of the implanted electrodes at 50 mV/s was 58.1 mC/cm2 on week 1 and 55.9 mC/cm2 on week 16, and at 50,000 mV/s, 4.27 mC/cm2 on week 1 and 5.93 mC/cm2 on week 16. Devices were able to record neural activity from 92% of all active channels at the beginning of the study, At the study endpoint, a-SiC devices were still recording single-unit activity on 51% of electrochemically active electrode channels. In addition, we observed that the signal-to-noise ratio experienced a small decline of -0.19 per week. We also classified observed units as fast and slow repolarizing based on the trough-to-peak time. Although the overall presence of single units declined, fast and slow repolarizing units declined at a similar rate. At recording electrode depth, immunohistochemistry showed minimal tissue response to the a-SiC devices, as indicated by statistically insignificant differences in activated glial cell response between implanted brains slices and contralateral sham slices at 150 μm away from the implant location, as evidenced by GFAP staining. NeuN staining revealed the presence of neuronal cell bodies close to the implantation site, again statistically not different from a contralateral sham slice. These results warrant further investigation of a-SiC MEAs for future long-term implantation neural recording studies.
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Affiliation(s)
- Justin R Abbott
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Eleanor N Jeakle
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Pegah Haghighi
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Joshua O Usoro
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Brandon S Sturgill
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Yupeng Wu
- Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Negar Geramifard
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Rahul Radhakrishna
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Sourav Patnaik
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Shido Nakajima
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Jordan Hess
- School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, United States
| | - Yusef Mehmood
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Veda Devata
- Department of Chemistry and Biochemistry, The University of Texas at Dallas, Richardson, TX, United States
| | - Gayathri Vijayakumar
- School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, United States
| | - Armaan Sood
- School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, United States
| | - Teresa Thuc Doan Thai
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Komal Dogra
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Ana G Hernandez-Reynoso
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Joseph J Pancrazio
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Stuart F Cogan
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States.
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2
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Sturgill B, Hernandez-Reynoso AG, Druschel LN, Smith TJ, Boucher PE, Hoeferlin GF, Thai TTD, Jiang MS, Hess JL, Alam NN, Menendez DM, Duncan JL, Cogan SF, Pancrazio JJ, Capadona JR. Reactive Amine Functionalized Microelectrode Arrays Provide Short-Term Benefit but Long-Term Detriment to In Vivo Recording Performance. ACS Appl Bio Mater 2024; 7:1052-1063. [PMID: 38290529 PMCID: PMC10880090 DOI: 10.1021/acsabm.3c01014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 01/08/2024] [Accepted: 01/10/2024] [Indexed: 02/01/2024]
Abstract
Intracortical microelectrode arrays (MEAs) are used for recording neural signals. However, indwelling devices result in chronic neuroinflammation, which leads to decreased recording performance through degradation of the device and surrounding tissue. Coating the MEAs with bioactive molecules is being explored to mitigate neuroinflammation. Such approaches often require an intermediate functionalization step such as (3-aminopropyl)triethoxysilane (APTES), which serves as a linker. However, the standalone effect of this intermediate step has not been previously characterized. Here, we investigated the effect of coating MEAs with APTES by comparing APTES-coated to uncoated controls in vivo and ex vivo. First, we measured water contact angles between silicon uncoated and APTES-coated substrates to verify the hydrophilic characteristics of the APTES coating. Next, we implanted MEAs in the motor cortex (M1) of Sprague-Dawley rats with uncoated or APTES-coated devices. We assessed changes in the electrochemical impedance and neural recording performance over a chronic implantation period of 16 weeks. Additionally, histology and bulk gene expression were analyzed to understand further the reactive tissue changes arising from the coating. Results showed that APTES increased the hydrophilicity of the devices and decreased electrochemical impedance at 1 kHz. APTES coatings proved detrimental to the recording performance, as shown by a constant decay up to 16 weeks postimplantation. Bulk gene analysis showed differential changes in gene expression between groups that were inconclusive with regard to the long-term effect on neuronal tissue. Together, these results suggest that APTES coatings are ultimately detrimental to chronic neural recordings. Furthermore, interpretations of studies using APTES as a functionalization step should consider the potential consequences if the final functionalization step is incomplete.
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Affiliation(s)
- Brandon
S. Sturgill
- Department
of Bioengineering, The University of Texas
at Dallas, 800 W. Campbell Road, Richardson, Texas 75080, United States
| | - Ana G. Hernandez-Reynoso
- Department
of Bioengineering, The University of Texas
at Dallas, 800 W. Campbell Road, Richardson, Texas 75080, United States
| | - Lindsey N. Druschel
- Department
of Biomedical Engineering, Case Western
Reserve University. 10900 Euclid Ave, Cleveland, Ohio 44106, United States
- Advanced
Platform Technology Center, Louis Stokes Cleveland Veterans Affairs
Medical Center, Cleveland, Ohio 44106, United States
| | - Thomas J. Smith
- School
of Behavioral and BrainSciences, The University
of Texas at Dallas, 800 W. Campbell Road, Richardson, Texas 75080, United States
| | - Pierce E. Boucher
- Department
of Biomedical Engineering, Case Western
Reserve University. 10900 Euclid Ave, Cleveland, Ohio 44106, United States
- Advanced
Platform Technology Center, Louis Stokes Cleveland Veterans Affairs
Medical Center, Cleveland, Ohio 44106, United States
| | - George F. Hoeferlin
- Department
of Biomedical Engineering, Case Western
Reserve University. 10900 Euclid Ave, Cleveland, Ohio 44106, United States
- Advanced
Platform Technology Center, Louis Stokes Cleveland Veterans Affairs
Medical Center, Cleveland, Ohio 44106, United States
| | - Teresa Thuc Doan Thai
- Department
of Bioengineering, The University of Texas
at Dallas, 800 W. Campbell Road, Richardson, Texas 75080, United States
| | - Madison S. Jiang
- School
of Behavioral and BrainSciences, The University
of Texas at Dallas, 800 W. Campbell Road, Richardson, Texas 75080, United States
| | - Jordan L. Hess
- School
of Behavioral and BrainSciences, The University
of Texas at Dallas, 800 W. Campbell Road, Richardson, Texas 75080, United States
| | - Neeha N. Alam
- Department
of Bioengineering, The University of Texas
at Dallas, 800 W. Campbell Road, Richardson, Texas 75080, United States
| | - Dhariyat M. Menendez
- Department
of Biomedical Engineering, Case Western
Reserve University. 10900 Euclid Ave, Cleveland, Ohio 44106, United States
- Advanced
Platform Technology Center, Louis Stokes Cleveland Veterans Affairs
Medical Center, Cleveland, Ohio 44106, United States
| | - Jonathan L. Duncan
- Department
of Biomedical Engineering, Case Western
Reserve University. 10900 Euclid Ave, Cleveland, Ohio 44106, United States
- Advanced
Platform Technology Center, Louis Stokes Cleveland Veterans Affairs
Medical Center, Cleveland, Ohio 44106, United States
| | - Stuart F. Cogan
- Department
of Bioengineering, The University of Texas
at Dallas, 800 W. Campbell Road, Richardson, Texas 75080, United States
| | - Joseph J. Pancrazio
- Department
of Bioengineering, The University of Texas
at Dallas, 800 W. Campbell Road, Richardson, Texas 75080, United States
| | - Jeffrey R. Capadona
- Department
of Biomedical Engineering, Case Western
Reserve University. 10900 Euclid Ave, Cleveland, Ohio 44106, United States
- Advanced
Platform Technology Center, Louis Stokes Cleveland Veterans Affairs
Medical Center, Cleveland, Ohio 44106, United States
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3
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Hernandez-Reynoso AG, Sturgill BS, Hoeferlin GF, Druschel LN, Krebs OK, Menendez DM, Thai TTD, Smith TJ, Duncan J, Zhang J, Mittal G, Radhakrishna R, Desai MS, Cogan SF, Pancrazio JJ, Capadona JR. The effect of a Mn(III)tetrakis(4-benzoic acid)porphyrin (MnTBAP) coating on the chronic recording performance of planar silicon intracortical microelectrode arrays. Biomaterials 2023; 303:122351. [PMID: 37931456 PMCID: PMC10842897 DOI: 10.1016/j.biomaterials.2023.122351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 09/27/2023] [Accepted: 10/11/2023] [Indexed: 11/08/2023]
Abstract
Intracortical microelectrode arrays (MEAs) are used to record neural activity. However, their implantation initiates a neuroinflammatory cascade, involving the accumulation of reactive oxygen species, leading to interface failure. Here, we coated commercially-available MEAs with Mn(III)tetrakis(4-benzoic acid)porphyrin (MnTBAP), to mitigate oxidative stress. First, we assessed the in vitro cytotoxicity of modified sample substrates. Then, we implanted 36 rats with uncoated, MnTBAP-coated ("Coated"), or (3-Aminopropyl)triethoxysilane (APTES)-coated devices - an intermediate step in the coating process. We assessed electrode performance during the acute (1-5 weeks), sub-chronic (6-11 weeks), and chronic (12-16 weeks) phases after implantation. Three subsets of animals were euthanized at different time points to assess the acute, sub-chronic and chronic immunohistological responses. Results showed that MnTBAP coatings were not cytotoxic in vitro, and their implantation in vivo improved the proportion of electrodes during the sub-chronic and chronic phases; APTES coatings resulted in failure of the neural interface during the chronic phase. In addition, MnTBAP coatings improved the quality of the signal throughout the study and reduced the neuroinflammatory response around the implant as early as two weeks, an effect that remained consistent for months post-implantation. Together, these results suggest that MnTBAP coatings are a potentially useful modification to improve MEA reliability.
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Affiliation(s)
- Ana G Hernandez-Reynoso
- Department of Bioengineering, The University of Texas at Dallas, 800 W Campbell Rd, Richardson, TX, 75080, United States.
| | - Brandon S Sturgill
- Department of Bioengineering, The University of Texas at Dallas, 800 W Campbell Rd, Richardson, TX, 75080, United States.
| | - George F Hoeferlin
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH, 44106, United States; Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, 10701 East Blvd, Cleveland, OH, 44106, United States.
| | - Lindsey N Druschel
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH, 44106, United States; Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, 10701 East Blvd, Cleveland, OH, 44106, United States.
| | - Olivia K Krebs
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH, 44106, United States; Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, 10701 East Blvd, Cleveland, OH, 44106, United States.
| | - Dhariyat M Menendez
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH, 44106, United States; Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, 10701 East Blvd, Cleveland, OH, 44106, United States.
| | - Teresa T D Thai
- Department of Bioengineering, The University of Texas at Dallas, 800 W Campbell Rd, Richardson, TX, 75080, United States.
| | - Thomas J Smith
- School of Behavioral and Brain Sciences, The University of Texas at Dallas, 800 W Campbell Rd, Richardson, TX, 75080, United States.
| | - Jonathan Duncan
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH, 44106, United States; Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, 10701 East Blvd, Cleveland, OH, 44106, United States.
| | - Jichu Zhang
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH, 44106, United States; Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, 10701 East Blvd, Cleveland, OH, 44106, United States.
| | - Gaurav Mittal
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH, 44106, United States; Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, 10701 East Blvd, Cleveland, OH, 44106, United States.
| | - Rahul Radhakrishna
- Department of Bioengineering, The University of Texas at Dallas, 800 W Campbell Rd, Richardson, TX, 75080, United States.
| | - Mrudang Spandan Desai
- Department of Bioengineering, The University of Texas at Dallas, 800 W Campbell Rd, Richardson, TX, 75080, United States.
| | - Stuart F Cogan
- Department of Bioengineering, The University of Texas at Dallas, 800 W Campbell Rd, Richardson, TX, 75080, United States.
| | - Joseph J Pancrazio
- Department of Bioengineering, The University of Texas at Dallas, 800 W Campbell Rd, Richardson, TX, 75080, United States.
| | - Jeffrey R Capadona
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH, 44106, United States; Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, 10701 East Blvd, Cleveland, OH, 44106, United States.
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4
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Li Y, Frederick RA, George D, Cogan SF, Pancrazio JJ, Bleris L, Hernandez-Reynoso AG. NeurostimML: A machine learning model for predicting neurostimulation-induced tissue damage. bioRxiv 2023:2023.10.18.562980. [PMID: 37905012 PMCID: PMC10614958 DOI: 10.1101/2023.10.18.562980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Objective The safe delivery of electrical current to neural tissue depends on many factors, yet previous methods for predicting tissue damage rely on only a few stimulation parameters. Here, we report the development of a machine learning approach that could lead to a more reliable method for predicting electrical stimulation-induced tissue damage by incorporating additional stimulation parameters. Approach A literature search was conducted to build an initial database of tissue response information after electrical stimulation, categorized as either damaging or non-damaging. Subsequently, we used ordinal encoding and random forest for feature selection, and investigated four machine learning models for classification: Logistic Regression, K-nearest Neighbor, Random Forest, and Multilayer Perceptron. Finally, we compared the results of these models against the accuracy of the Shannon equation. Main Results We compiled a database with 387 unique stimulation parameter combinations collected from 58 independent studies conducted over a period of 47 years, with 195 (51%) categorized as non-damaging and 190 (49%) categorized as damaging. The features selected for building our model with a Random Forest algorithm were: waveform shape, geometric surface area, pulse width, frequency, pulse amplitude, charge per phase, charge density, current density, duty cycle, daily stimulation duration, daily number of pulses delivered, and daily accumulated charge. The Shannon equation yielded an accuracy of 63.9% using a k value of 1.79. In contrast, the Random Forest algorithm was able to robustly predict whether a set of stimulation parameters was classified as damaging or non-damaging with an accuracy of 88.3%. Significance This novel Random Forest model can facilitate more informed decision making in the selection of neuromodulation parameters for both research studies and clinical practice. This study represents the first approach to use machine learning in the prediction of stimulation-induced neural tissue damage, and lays the groundwork for neurostimulation driven by machine learning models.
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Affiliation(s)
- Yi Li
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA
- Center for Systems Biology, The University of Texas at Dallas, Richardson, TX, USA
| | - Rebecca A. Frederick
- Phil and Penny Knight Campus for Accelerating Scientific Impact, University of Oregon, Eugene, OR, USA
| | - Daniel George
- Department of Computer Science, The University of Texas at Dallas, Richardson, TX, USA
| | - Stuart F. Cogan
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA
| | - Joseph J. Pancrazio
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA
| | - Leonidas Bleris
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA
- Center for Systems Biology, The University of Texas at Dallas, Richardson, TX, USA
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
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5
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Hoeferlin GF, Bajwa T, Olivares H, Zhang J, Druschel LN, Sturgill BS, Sobota M, Boucher P, Duncan J, Hernandez-Reynoso AG, Cogan SF, Pancrazio JJ, Capadona JR. Antioxidant Dimethyl Fumarate Temporarily but Not Chronically Improves Intracortical Microelectrode Performance. Micromachines (Basel) 2023; 14:1902. [PMID: 37893339 PMCID: PMC10609067 DOI: 10.3390/mi14101902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 09/24/2023] [Accepted: 10/02/2023] [Indexed: 10/29/2023]
Abstract
Intracortical microelectrode arrays (MEAs) can be used in a range of applications, from basic neuroscience research to providing an intimate interface with the brain as part of a brain-computer interface (BCI) system aimed at restoring function for people living with neurological disorders or injuries. Unfortunately, MEAs tend to fail prematurely, leading to a loss in functionality for many applications. An important contributing factor in MEA failure is oxidative stress resulting from chronically inflammatory-activated microglia and macrophages releasing reactive oxygen species (ROS) around the implant site. Antioxidants offer a means for mitigating oxidative stress and improving tissue health and MEA performance. Here, we investigate using the clinically available antioxidant dimethyl fumarate (DMF) to reduce the neuroinflammatory response and improve MEA performance in a rat MEA model. Daily treatment of DMF for 16 weeks resulted in a significant improvement in the recording capabilities of MEA devices during the sub-chronic (Weeks 5-11) phase (42% active electrode yield vs. 35% for control). However, these sub-chronic improvements were lost in the chronic implantation phase, as a more exacerbated neuroinflammatory response occurs in DMF-treated animals by 16 weeks post-implantation. Yet, neuroinflammation was indiscriminate between treatment and control groups during the sub-chronic phase. Although worse for chronic use, a temporary improvement (<12 weeks) in MEA performance is meaningful. Providing short-term improvement to MEA devices using DMF can allow for improved use for limited-duration studies. Further efforts should be taken to explore the mechanism behind a worsened neuroinflammatory response at the 16-week time point for DMF-treated animals and assess its usefulness for specific applications.
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Affiliation(s)
- George F. Hoeferlin
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH 44106, USA (H.O.); (J.D.)
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, 10701 East Blvd, Cleveland, OH 44106, USA
| | - Tejas Bajwa
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH 44106, USA (H.O.); (J.D.)
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, 10701 East Blvd, Cleveland, OH 44106, USA
| | - Hannah Olivares
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH 44106, USA (H.O.); (J.D.)
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, 10701 East Blvd, Cleveland, OH 44106, USA
| | - Jichu Zhang
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH 44106, USA (H.O.); (J.D.)
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, 10701 East Blvd, Cleveland, OH 44106, USA
| | - Lindsey N. Druschel
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH 44106, USA (H.O.); (J.D.)
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, 10701 East Blvd, Cleveland, OH 44106, USA
| | - Brandon S. Sturgill
- Department of Bioengineering, The University of Texas at Dallas, 800 W Campbell Rd, Richardson, TX 75080, USA (J.J.P.)
| | - Michael Sobota
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH 44106, USA (H.O.); (J.D.)
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, 10701 East Blvd, Cleveland, OH 44106, USA
| | - Pierce Boucher
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH 44106, USA (H.O.); (J.D.)
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, 10701 East Blvd, Cleveland, OH 44106, USA
| | - Jonathan Duncan
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH 44106, USA (H.O.); (J.D.)
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, 10701 East Blvd, Cleveland, OH 44106, USA
| | - Ana G. Hernandez-Reynoso
- Department of Bioengineering, The University of Texas at Dallas, 800 W Campbell Rd, Richardson, TX 75080, USA (J.J.P.)
| | - Stuart F. Cogan
- Department of Bioengineering, The University of Texas at Dallas, 800 W Campbell Rd, Richardson, TX 75080, USA (J.J.P.)
| | - Joseph J. Pancrazio
- Department of Bioengineering, The University of Texas at Dallas, 800 W Campbell Rd, Richardson, TX 75080, USA (J.J.P.)
| | - Jeffrey R. Capadona
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH 44106, USA (H.O.); (J.D.)
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, 10701 East Blvd, Cleveland, OH 44106, USA
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6
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Solis EM, Good LB, Vázquez RG, Patnaik S, Hernandez-Reynoso AG, Ma Q, Angulo G, Dobariya A, Cogan SF, Pancrazio JJ, Pascual JM, Jakkamsetti V. Isolation of the murine Glut1 deficient thalamocortical circuit: wavelet characterization and reverse glucose dependence of low and gamma frequency oscillations. Front Neurosci 2023; 17:1191492. [PMID: 37829723 PMCID: PMC10565352 DOI: 10.3389/fnins.2023.1191492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 08/25/2023] [Indexed: 10/14/2023] Open
Abstract
Glucose represents the principal brain energy source. Thus, not unexpectedly, genetic glucose transporter 1 (Glut1) deficiency (G1D) manifests with encephalopathy. G1D seizures, which constitute a prominent disease manifestation, often prove refractory to medications but may respond to therapeutic diets. These seizures are associated with aberrant thalamocortical oscillations as inferred from human electroencephalography and functional imaging. Mouse electrophysiological recordings indicate that inhibitory neuron failure in thalamus and cortex underlies these abnormalities. This provides the motivation to develop a neural circuit testbed to characterize the mechanisms of thalamocortical synchronization and the effects of known or novel interventions. To this end, we used mouse thalamocortical slices on multielectrode arrays and characterized spontaneous low frequency oscillations and less frequent 30-50 Hz or gamma oscillations under near-physiological bath glucose concentration. Using the cortical recordings from layer IV among other regions recorded, we quantified oscillation epochs via an automated wavelet-based algorithm. This method proved analytically superior to power spectral density, short-time Fourier transform or amplitude-threshold detection. As expected from human observations, increased bath glucose reduced the lower frequency oscillations while augmenting the gamma oscillations, likely reflecting strengthened inhibitory neuron activity, and thus decreasing the low:high frequency ratio (LHR). This approach provides an ex vivo method for the evaluation of mechanisms, fuels, and pharmacological agents in a crucial G1D epileptogenic circuit.
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Affiliation(s)
- Elysandra M. Solis
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Levi B. Good
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Rafael Granja Vázquez
- Department of Neuroscience and the Center for Advanced Pain Studies, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Sourav Patnaik
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | | | - Qian Ma
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Gustavo Angulo
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Aksharkumar Dobariya
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Stuart F. Cogan
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Joseph J. Pancrazio
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Juan M. Pascual
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Physiology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Eugene McDermott Center for Human Growth & Development/Center for Human Genetics, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Vikram Jakkamsetti
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
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7
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Solis EM, Good LB, Granja Vázquez R, Patnaik S, Hernandez-Reynoso AG, Ma Q, Angulo G, Dobariya A, Cogan SF, Pancrazio JJ, Pascual JM, Jakkamsetti V. Isolation of the murine Glut1 deficient thalamocortical circuit: wavelet characterization and reverse glucose dependence of low and gamma frequency oscillations. bioRxiv 2023:2023.06.05.543611. [PMID: 37645928 PMCID: PMC10461930 DOI: 10.1101/2023.06.05.543611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Glucose represents the principal brain energy source. Thus, not unexpectedly, genetic glucose transporter 1 (Glut1) deficiency (G1D) manifests with encephalopathy. G1D seizures, which constitute a prominent disease manifestation, often prove refractory to medications but may respond to therapeutic diets. These seizures are associated with aberrant thalamocortical oscillations as inferred from human electroencephalography and functional imaging. Mouse electrophysiological recordings indicate that inhibitory neuron failure in thalamus and cortex underlies these abnormalities. This provides the motivation to develop a neural circuit testbed to characterize the mechanisms of thalamocortical synchronization and the effects of known or novel interventions. To this end, we used mouse thalamocortical slices on multielectrode arrays and characterized spontaneous low frequency oscillations and less frequent 30-50 Hz or gamma oscillations under near-physiological bath glucose concentration. Using the cortical recordings from layer IV, we quantified oscillation epochs via an automated wavelet-based algorithm. This method proved analytically superior to power spectral density, short-time Fourier transform or amplitude-threshold detection. As expected from human observations, increased bath glucose reduced the lower frequency oscillations while augmenting the gamma oscillations, likely reflecting strengthened inhibitory neuron activity. This approach provides an ex vivo method for the evaluation of mechanisms, fuels, and pharmacological agents in a crucial G1D epileptogenic circuit.
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Affiliation(s)
- Elysandra M. Solis
- Department of Bioengineering; The University of Texas at Dallas, Richardson, Texas, USA
| | - Levi B. Good
- Department of Bioengineering; The University of Texas at Dallas, Richardson, Texas, USA
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Neurology; The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Rafael Granja Vázquez
- Department of Bioengineering; The University of Texas at Dallas, Richardson, Texas, USA
| | - Sourav Patnaik
- Department of Bioengineering; The University of Texas at Dallas, Richardson, Texas, USA
| | | | - Qian Ma
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Neurology; The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Gustavo Angulo
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Neurology; The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Aksharkumar Dobariya
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Neurology; The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Stuart F. Cogan
- Department of Bioengineering; The University of Texas at Dallas, Richardson, Texas, USA
| | - Joseph J. Pancrazio
- Department of Bioengineering; The University of Texas at Dallas, Richardson, Texas, USA
| | - Juan M. Pascual
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Neurology; The University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Physiology; The University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Pediatrics; The University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Eugene McDermott Center for Human Growth & Development / Center for Human Genetics; The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Vikram Jakkamsetti
- Department of Bioengineering; The University of Texas at Dallas, Richardson, Texas, USA
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
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8
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Brown MA, Zappitelli KM, Singh L, Yuan RC, Bemrose M, Brogden V, Miller DJ, Smear MC, Cogan SF, Gardner TJ. Direct laser writing of 3D electrodes on flexible substrates. Nat Commun 2023; 14:3610. [PMID: 37330565 PMCID: PMC10276853 DOI: 10.1038/s41467-023-39152-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 05/31/2023] [Indexed: 06/19/2023] Open
Abstract
This report describes a 3D microelectrode array integrated on a thin-film flexible cable for neural recording in small animals. The fabrication process combines traditional silicon thin-film processing techniques and direct laser writing of 3D structures at micron resolution via two-photon lithography. Direct laser-writing of 3D-printed electrodes has been described before, but this report is the first to provide a method for producing high-aspect-ratio structures. One prototype, a 16-channel array with 300 µm pitch, demonstrates successful electrophysiological signal capture from bird and mouse brains. Additional devices include 90 µm pitch arrays, biomimetic mosquito needles that penetrate through the dura of birds, and porous electrodes with enhanced surface area. The rapid 3D printing and wafer-scale methods described here will enable efficient device fabrication and new studies examining the relationship between electrode geometry and electrode performance. Applications include small animal models, nerve interfaces, retinal implants, and other devices requiring compact, high-density 3D electrodes.
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Affiliation(s)
- Morgan A Brown
- Phil and Penny Knight Campus for Accelerating Scientific Impact, University of Oregon, Eugene, OR, USA
| | - Kara M Zappitelli
- Phil and Penny Knight Campus for Accelerating Scientific Impact, University of Oregon, Eugene, OR, USA
| | - Loveprit Singh
- Phil and Penny Knight Campus for Accelerating Scientific Impact, University of Oregon, Eugene, OR, USA
| | - Rachel C Yuan
- Phil and Penny Knight Campus for Accelerating Scientific Impact, University of Oregon, Eugene, OR, USA
| | - Melissa Bemrose
- Phil and Penny Knight Campus for Accelerating Scientific Impact, University of Oregon, Eugene, OR, USA
| | - Valerie Brogden
- Phil and Penny Knight Campus for Accelerating Scientific Impact, University of Oregon, Eugene, OR, USA
| | - David J Miller
- Phil and Penny Knight Campus for Accelerating Scientific Impact, University of Oregon, Eugene, OR, USA
| | - Matthew C Smear
- Phil and Penny Knight Campus for Accelerating Scientific Impact, University of Oregon, Eugene, OR, USA
| | - Stuart F Cogan
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA
| | - Timothy J Gardner
- Phil and Penny Knight Campus for Accelerating Scientific Impact, University of Oregon, Eugene, OR, USA.
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Smith TJ, Wu Y, Cheon C, Khan AA, Srinivasan H, Capadona JR, Cogan SF, Pancrazio JJ, Engineer CT, Hernandez-Reynoso AG. Behavioral paradigm for the evaluation of stimulation-evoked somatosensory perception thresholds in rats. Front Neurosci 2023; 17:1202258. [PMID: 37383105 PMCID: PMC10293669 DOI: 10.3389/fnins.2023.1202258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 05/22/2023] [Indexed: 06/30/2023] Open
Abstract
Intracortical microstimulation (ICMS) of the somatosensory cortex via penetrating microelectrode arrays (MEAs) can evoke cutaneous and proprioceptive sensations for restoration of perception in individuals with spinal cord injuries. However, ICMS current amplitudes needed to evoke these sensory percepts tend to change over time following implantation. Animal models have been used to investigate the mechanisms by which these changes occur and aid in the development of new engineering strategies to mitigate such changes. Non-human primates are commonly the animal of choice for investigating ICMS, but ethical concerns exist regarding their use. Rodents are a preferred animal model due to their availability, affordability, and ease of handling, but there are limited choices of behavioral tasks for investigating ICMS. In this study, we investigated the application of an innovative behavioral go/no-go paradigm capable of estimating ICMS-evoked sensory perception thresholds in freely moving rats. We divided animals into two groups, one receiving ICMS and a control group receiving auditory tones. Then, we trained the animals to nose-poke - a well-established behavioral task for rats - following either a suprathreshold ICMS current-controlled pulse train or frequency-controlled auditory tone. Animals received a sugar pellet reward when nose-poking correctly. When nose-poking incorrectly, animals received a mild air puff. After animals became proficient in this task, as defined by accuracy, precision, and other performance metrics, they continued to the next phase for perception threshold detection, where we varied the ICMS amplitude using a modified staircase method. Finally, we used non-linear regression to estimate perception thresholds. Results indicated that our behavioral protocol could estimate ICMS perception thresholds based on ~95% accuracy of rat nose-poke responses to the conditioned stimulus. This behavioral paradigm provides a robust methodology for evaluating stimulation-evoked somatosensory percepts in rats comparable to the evaluation of auditory percepts. In future studies, this validated methodology can be used to study the performance of novel MEA device technologies on ICMS-evoked perception threshold stability using freely moving rats or to investigate information processing principles in neural circuits related to sensory perception discrimination.
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Affiliation(s)
- Thomas J. Smith
- School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, United States
| | - Yupeng Wu
- Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Claire Cheon
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Arlin A. Khan
- School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, United States
| | - Hari Srinivasan
- School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, United States
| | - Jeffrey R. Capadona
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH, United States
| | - Stuart F. Cogan
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Joseph J. Pancrazio
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Crystal T. Engineer
- School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, United States
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, United States
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10
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Smith TJ, Wu Y, Cheon C, Khan AA, Srinivasan H, Capadona JR, Cogan SF, Pancrazio JJ, Engineer CT, Hernandez-Reynoso AG. Behavioral Paradigm for the Evaluation of Stimulation-Evoked Somatosensory Perception Thresholds in Rats. bioRxiv 2023:2023.05.04.537848. [PMID: 37205577 PMCID: PMC10187227 DOI: 10.1101/2023.05.04.537848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Intracortical microstimulation (ICMS) of the somatosensory cortex via penetrating microelectrode arrays (MEAs) can evoke cutaneous and proprioceptive sensations for restoration of perception in individuals with spinal cord injuries. However, ICMS current amplitudes needed to evoke these sensory percepts tend to change over time following implantation. Animal models have been used to investigate the mechanisms by which these changes occur and aid in the development of new engineering strategies to mitigate such changes. Non-human primates are commonly the animal of choice for investigating ICMS, but ethical concerns exist regarding their use. Rodents are a preferred animal model due to their availability, affordability, and ease of handling, but there are limited choices of behavioral tasks for investigating ICMS. In this study, we investigated the application of an innovative behavioral go/no-go paradigm capable of estimating ICMS-evoked sensory perception thresholds in freely moving rats. We divided animals into two groups, one receiving ICMS and a control group receiving auditory tones. Then, we trained the animals to nose-poke - a well-established behavioral task for rats - following either a suprathreshold ICMS current-controlled pulse train or frequency-controlled auditory tone. Animals received a sugar pellet reward when nose-poking correctly. When nose-poking incorrectly, animals received a mild air puff. After animals became proficient in this task, as defined by accuracy, precision, and other performance metrics, they continued to the next phase for perception threshold detection, where we varied the ICMS amplitude using a modified staircase method. Finally, we used non-linear regression to estimate perception thresholds. Results indicated that our behavioral protocol could estimate ICMS perception thresholds based on ∼95% accuracy of rat nose-poke responses to the conditioned stimulus. This behavioral paradigm provides a robust methodology for evaluating stimulation-evoked somatosensory percepts in rats comparable to the evaluation of auditory percepts. In future studies, this validated methodology can be used to study the performance of novel MEA device technologies on ICMS-evoked perception threshold stability using freely moving rats or to investigate information processing principles in neural circuits related to sensory perception discrimination.
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11
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Jeakle EN, Abbott JR, Usoro JO, Wu Y, Haghighi P, Radhakrishna R, Sturgill BS, Nakajima S, Thai TTD, Pancrazio JJ, Cogan SF, Hernandez-Reynoso AG. Chronic Stability of Local Field Potentials Using Amorphous Silicon Carbide Microelectrode Arrays Implanted in the Rat Motor Cortex. Micromachines (Basel) 2023; 14:680. [PMID: 36985087 PMCID: PMC10054633 DOI: 10.3390/mi14030680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 03/15/2023] [Accepted: 03/17/2023] [Indexed: 06/18/2023]
Abstract
Implantable microelectrode arrays (MEAs) enable the recording of electrical activity of cortical neurons, allowing the development of brain-machine interfaces. However, MEAs show reduced recording capabilities under chronic conditions, prompting the development of novel MEAs that can improve long-term performance. Conventional planar, silicon-based devices and ultra-thin amorphous silicon carbide (a-SiC) MEAs were implanted in the motor cortex of female Sprague-Dawley rats, and weekly anesthetized recordings were made for 16 weeks after implantation. The spectral density and bandpower between 1 and 500 Hz of recordings were compared over the implantation period for both device types. Initially, the bandpower of the a-SiC devices and standard MEAs was comparable. However, the standard MEAs showed a consistent decline in both bandpower and power spectral density throughout the 16 weeks post-implantation, whereas the a-SiC MEAs showed substantially more stable performance. These differences in bandpower and spectral density between standard and a-SiC MEAs were statistically significant from week 6 post-implantation until the end of the study at 16 weeks. These results support the use of ultra-thin a-SiC MEAs to develop chronic, reliable brain-machine interfaces.
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Affiliation(s)
- Eleanor N. Jeakle
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080-3021, USA
| | - Justin R. Abbott
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080-3021, USA
| | - Joshua O. Usoro
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080-3021, USA
| | - Yupeng Wu
- Department of Materials Science and Engineering, The University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080-3021, USA
| | - Pegah Haghighi
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080-3021, USA
| | - Rahul Radhakrishna
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080-3021, USA
| | - Brandon S. Sturgill
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080-3021, USA
| | - Shido Nakajima
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080-3021, USA
| | - Teresa T. D. Thai
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080-3021, USA
| | - Joseph J. Pancrazio
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080-3021, USA
| | - Stuart F. Cogan
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080-3021, USA
| | - Ana G. Hernandez-Reynoso
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080-3021, USA
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12
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Geramifard N, Lawson J, Cogan SF, Black BJ. A Novel 3D Helical Microelectrode Array for In Vitro Extracellular Action Potential Recording. Micromachines (Basel) 2022; 13:1692. [PMID: 36296045 PMCID: PMC9611359 DOI: 10.3390/mi13101692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Revised: 09/25/2022] [Accepted: 09/27/2022] [Indexed: 06/16/2023]
Abstract
Recent advances in cell and tissue engineering have enabled long-term three-dimensional (3D) in vitro cultures of human-derived neuronal tissues. Analogous two-dimensional (2D) tissue cultures have been used for decades in combination with substrate integrated microelectrode arrays (MEA) for pharmacological and toxicological assessments. While the phenotypic and cytoarchitectural arguments for 3D culture are clear, 3D MEA technologies are presently inadequate. This is mostly due to the technical challenge of creating vertical electrical conduction paths (or 'traces') using standardized biocompatible materials and fabrication techniques. Here, we have circumvented that challenge by designing and fabricating a novel helical 3D MEA comprised of polyimide, amorphous silicon carbide (a-SiC), gold/titanium, and sputtered iridium oxide films (SIROF). Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) testing confirmed fully-fabricated MEAs should be capable of recording extracellular action potentials (EAPs) with high signal-to-noise ratios (SNR). We then seeded induced pluripotent stems cell (iPSC) sensory neurons (SNs) in a 3D collagen-based hydrogel integrated with the helical MEAs and recorded EAPs for up to 28 days in vitro from across the MEA volume. Importantly, this highly adaptable design does not intrinsically limit cell/tissue type, channel count, height, or total volume.
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Affiliation(s)
- Negar Geramifard
- Department of Bioengineering, Erik Jonsson School of Engineering and Computer Science, University of Texas at Dallas, Richardson, TX 75080, USA
| | - Jennifer Lawson
- Biomedical Engineering Department, Francis College of Engineering, University of Massachusetts Lowell, Lowell, MA 01854, USA
| | - Stuart F. Cogan
- Department of Bioengineering, Erik Jonsson School of Engineering and Computer Science, University of Texas at Dallas, Richardson, TX 75080, USA
| | - Bryan James Black
- Biomedical Engineering Department, Francis College of Engineering, University of Massachusetts Lowell, Lowell, MA 01854, USA
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13
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Dobariya A, El Ahmadieh TY, Good LB, Hernandez-Reynoso AG, Jakkamsetti V, Brown R, Dunbar M, Ding K, Luna J, Kallem RR, Putnam WC, Shelton JM, Evers BM, Azami A, Geramifard N, Cogan SF, Mickey B, Pascual JM. Recording of pig neuronal activity in the comparative context of the awake human brain. Sci Rep 2022; 12:15503. [PMID: 36109613 PMCID: PMC9478131 DOI: 10.1038/s41598-022-19688-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 09/01/2022] [Indexed: 11/09/2022] Open
Abstract
Gyriform mammals display neurophysiological and neural network activity that other species exhibit only in rudimentary or dissimilar form. However, neural recordings from large mammals such as the pig can be anatomically hindered and pharmacologically suppressed by anesthetics. This curtails comparative inferences. To mitigate these limitations, we set out to modify electrocorticography, intracerebral depth and intracortical recording methods to study the anesthetized pig. In the process, we found that common forms of infused anesthesia such as pentobarbital or midazolam can be neurophysiologic suppressants acting in dose-independent fashion relative to anesthetic dose or brain concentration. Further, we corroborated that standard laboratory conditions may impose electrical interference with specific neural signals. We thus aimed to safeguard neural network integrity and recording fidelity by developing surgical, anesthesia and noise reduction methods and by working inside a newly designed Faraday cage, and evaluated this from the point of view of neurophysiological power spectral density and coherence analyses. We also utilized novel silicon carbide electrodes to minimize mechanical disruption of single-neuron activity. These methods allowed for the preservation of native neurophysiological activity for several hours. Pig electrocorticography recordings were essentially indistinguishable from awake human recordings except for the small segment of electrical activity associated with vision in conscious persons. In addition, single-neuron and paired-pulse stimulation recordings were feasible simultaneously with electrocorticography and depth electrode recordings. The spontaneous and stimulus-elicited neuronal activities thus surveyed can be recorded with a degree of precision similar to that achievable in rodent or any other animal studies and prove as informative as unperturbed human electrocorticography.
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Affiliation(s)
- Aksharkumar Dobariya
- Rare Brain Disorders Program, Department of Neurology, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd. Mail Code 8813, Dallas, TX, 75390-8813, USA
| | - Tarek Y El Ahmadieh
- Department of Neurosurgery, Loma Linda University Medical Center, Loma Linda, CA, 92354, USA
| | - Levi B Good
- Rare Brain Disorders Program, Department of Neurology, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd. Mail Code 8813, Dallas, TX, 75390-8813, USA
| | | | - Vikram Jakkamsetti
- Rare Brain Disorders Program, Department of Neurology, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd. Mail Code 8813, Dallas, TX, 75390-8813, USA
| | - Ronnie Brown
- Department of Neurological Surgery, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Misha Dunbar
- Animal Resource Center, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Kan Ding
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Jesus Luna
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Raja Reddy Kallem
- Department of Pharmacy Practice and Clinical Pharmacology, Experimental Therapeutics Center, Texas Tech University Health Sciences Center, Dallas, TX, 75235, USA
| | - William C Putnam
- Department of Pharmacy Practice and Clinical Pharmacology, Experimental Therapeutics Center, Texas Tech University Health Sciences Center, Dallas, TX, 75235, USA
- Department of Pharmaceutical Science, School of Pharmacy, Texas Tech University Health Sciences Center, Dallas, TX, 75235, USA
| | - John M Shelton
- Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Bret M Evers
- Department of Pathology, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Amirhossein Azami
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Negar Geramifard
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Stuart F Cogan
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Bruce Mickey
- Department of Neurological Surgery, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Juan M Pascual
- Rare Brain Disorders Program, Department of Neurology, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd. Mail Code 8813, Dallas, TX, 75390-8813, USA.
- Department of Physiology, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
- Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
- Eugene McDermott Center for Human Growth and Development/Center for Human Genetics, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
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Frederick RA, Shih E, Towle VL, Joshi-Imre A, Troyk PR, Cogan SF. Chronic stability of activated iridium oxide film voltage transients from wireless floating microelectrode arrays. Front Neurosci 2022; 16:876032. [PMID: 36003961 PMCID: PMC9393423 DOI: 10.3389/fnins.2022.876032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 06/28/2022] [Indexed: 11/22/2022] Open
Abstract
Successful monitoring of the condition of stimulation electrodes is critical for maintaining chronic device performance for neural stimulation. As part of pre-clinical safety testing in preparation for a visual prostheses clinical trial, we evaluated the stability of the implantable devices and stimulation electrodes using a combination of current pulsing in saline and in canine visual cortex. Specifically, in saline we monitored the stability and performance of 3000 μm2 geometric surface area activated iridium oxide film (AIROF) electrodes within a wireless floating microelectrode array (WFMA) by measuring the voltage transient (VT) response through reverse telemetry. Eight WFMAs were assessed in vitro for 24 days, where n = 4 were pulsed continuously at 80 μA (16 nC/phase) and n = 4 remained in solution with no applied stimulation. Subsequently, twelve different WFMAs were implanted in visual cortex in n = 3 canine subjects (4 WFMAs each). After a 2-week recovery period, half of the electrodes in each of the twelve devices were pulsed continuously for 24 h at either 20, 40, 63, or 80 μA (200 μs pulse width, 100 Hz). VTs were recorded to track changes in the electrodes at set time intervals in both the saline and in vivo study. The VT response of AIROF electrodes remained stable during pulsing in saline over 24 days. Electrode polarization and driving voltage changed by less than 200 mV on average. The AIROF electrodes also maintained consistent performance, overall, during 24 h of pulsing in vivo. Four of the in vivo WFMA devices showed a change in polarization, access voltage, or driving voltage over time. However, no VT recordings indicated electrode failure, and the same trend was typically seen in both pulsed and unpulsed electrodes within the same device. Overall, accelerated stimulation testing in saline and in vivo indicated that AIROF electrodes in the WFMA were able to consistently deliver up to 16 nC per pulse and would be suitable for chronic clinical use.
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Affiliation(s)
- Rebecca A. Frederick
- Neural Interfaces Laboratory, Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Ellen Shih
- Neural Interfaces Laboratory, Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Vernon L. Towle
- Clinical Neurophysiologic Mapping Laboratory, Department of Neurology, The University of Chicago, Chicago, IL, United States
| | - Alexandra Joshi-Imre
- Neural Interfaces Laboratory, Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Philip R. Troyk
- Laboratory of Neuroprosthetic Research, Department of Biomedical Engineering, Illinois Institute of Technology, Chicago, IL, United States
| | - Stuart F. Cogan
- Neural Interfaces Laboratory, Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
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15
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Ghazavi A, Cogan SF. Ultramicro-sized sputtered iridium oxide electrodes in buffered saline: Behavior, stability, and the effect of the perimeter to area ratio on their electrochemical properties. Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2022.140514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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16
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Krebs OK, Mittal G, Ramani S, Zhang J, Shoffstall AJ, Cogan SF, Pancrazio JJ, Capadona JR. Tools for Surface Treatment of Silicon Planar Intracortical Microelectrodes. J Vis Exp 2022. [PMID: 35758655 DOI: 10.3791/63500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Intracortical microelectrodes hold great therapeutic potential. But they are challenged with significant performance reduction after modest implantation durations. A substantial contributor to the observed decline is the damage to the neural tissue proximal to the implant and subsequent neuroinflammatory response. Efforts to improve device longevity include chemical modifications or coating applications to the device surface to improve the tissue response. Development of such surface treatments is typically completed using non-functional "dummy" probes that lack the electrical components required for the intended application. Translation to functional devices requires additional consideration given the fragility of intracortical microelectrode arrays. Handling tools greatly facilitate surface treatments to assembled devices, particularly for modifications that require long procedural times. The handling tools described here are used for surface treatments applied via gas-phase deposition and aqueous solution exposure. Characterization of the coating is performed using ellipsometry and x-ray photoelectron spectroscopy. A comparison of electrical impedance spectroscopy recordings before and after the coating procedure on functional devices confirmed device integrity following modification. The described tools can be readily adapted for alternative electrode devices and treatment methods that maintain chemical compatibility.
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Affiliation(s)
- Olivia K Krebs
- Department of Biomedical Engineering, Case Western Reserve University; Advanced Platform Technology Center, Rehabilitation Research and Development, Louis Stokes Cleveland Department of Veterans Affairs Medical Center
| | - Gaurav Mittal
- Department of Biomedical Engineering, Case Western Reserve University; Advanced Platform Technology Center, Rehabilitation Research and Development, Louis Stokes Cleveland Department of Veterans Affairs Medical Center
| | - Shreya Ramani
- Department of Biomedical Engineering, Case Western Reserve University; Advanced Platform Technology Center, Rehabilitation Research and Development, Louis Stokes Cleveland Department of Veterans Affairs Medical Center
| | - Jichu Zhang
- Department of Biomedical Engineering, Case Western Reserve University; Advanced Platform Technology Center, Rehabilitation Research and Development, Louis Stokes Cleveland Department of Veterans Affairs Medical Center
| | - Andrew J Shoffstall
- Department of Biomedical Engineering, Case Western Reserve University; Advanced Platform Technology Center, Rehabilitation Research and Development, Louis Stokes Cleveland Department of Veterans Affairs Medical Center
| | - Stuart F Cogan
- Department of Bioengineering, The University of Texas at Dallas
| | | | - Jeffrey R Capadona
- Department of Biomedical Engineering, Case Western Reserve University; Advanced Platform Technology Center, Rehabilitation Research and Development, Louis Stokes Cleveland Department of Veterans Affairs Medical Center;
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Chakraborty B, Joshi-Imre A, Cogan SF. Charge injection characteristics of sputtered ruthenium oxide electrodes for neural stimulation and recording. J Biomed Mater Res B Appl Biomater 2022; 110:229-238. [PMID: 34259381 PMCID: PMC8608743 DOI: 10.1002/jbm.b.34906] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 06/23/2021] [Accepted: 06/27/2021] [Indexed: 01/03/2023]
Abstract
We have studied the charge-injection characteristics and electrochemical impedance of sputtered ruthenium oxide (RuOx ) films as electrode coatings for neural stimulation and recording electrodes. RuOx films were deposited by reactive DC magnetron sputtering, using a combination of water vapor and oxygen gas as reactive plasma constituents. The cathodal charge storage capacity of planar RuOx electrodes was found to be 54.6 ± 9.5 mC/cm2 (mean ± SD, n = 12), and the charge-injection capacity in a 0.2-ms cathodal current pulse was found to be 7.1 ± 0.3 mC/cm2 (mean ± SD, n = 15) at 0.6 V positive bias versus Ag|AgCl, in phosphate buffer saline at room temperature for ~250 nm thick films. In general, the RuOx films exhibited high charge-injection capacities, with or without a positive interpulse bias, comparable to sputtered iridium oxide (SIROF) coatings. The charge-injection capacity increased monotonically with film thickness from 120 to 630 nm, and reached 11.30 ± 0.34 mC/cm2 (mean ± SD, n = 5) at 0.6 V bias versus Ag|AgCl at 630 nm film thickness. In addition, RuOx films showed minimal changes in electrochemical characteristics over 1.5 billion cycles of constant current pulsing at a charge density of 408 μC/cm2 (8 nC/phase, 200 μs pulse width). The findings of low-impedance, high charge-injection capacity, and long-term pulsing stability suggest the suitability of RuOx as a comparatively inexpensive and favorable choice of electrode material for neural stimulation and recording.
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Affiliation(s)
- Bitan Chakraborty
- Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, Texas, USA
| | - Alexandra Joshi-Imre
- Department of Research, The University of Texas at Dallas, Richardson, Texas, USA
| | - Stuart F. Cogan
- Department of Bioengineering, The University of Texas at Dallas, Richardson, Texas, USA
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Nguyen CK, Abbott JR, Negi S, Cogan SF. Evaluation of Amorphous Silicon Carbide on Utah Electrode Arrays by Thermal Accelerated Aging . Annu Int Conf IEEE Eng Med Biol Soc 2021; 2021:6623-6626. [PMID: 34892626 DOI: 10.1109/embc46164.2021.9629701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Long-term microelectrode arrays (MEAs) are essential devices for studying neural activity and stimulating neurons for treating neurological disorders or for recording neural activity to control prosthesis. However, practical use of MEAs is impeded by unreliable chronic stability inside the host body. We are proposing to implement amorphous silicon carbide (a-SiC) as a replacement for the current standard practice of using Parylene-C encapsulation on commercial Utah electrode arrays (UEAs) manufactured by Blackrock Neurotech. By using thermal accelerated aging (TAA), we can theoretically evaluate the lifetime stabilities in comparatively short time. After 255 days at 87°C in phosphate-buffered saline (PBS), a device has theoretically reached ~22 years at 37°C in PBS. We report on a study of an a-SiC UEA using stability criteria of impedance (Z1kHz < 70 kΩ) and cathodal charge storage capacity (CSCc > 10 mC/cm2). At 255 days, no total electrode failures have been observed.Clinical Relevance- This research demonstrates the suitability of a-SiC to encapsulate MEAs during under long-term stability in saline environments.
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Abbott JR, Joshi-Imre A, Cogan SF. In Vitro Electrochemical Properties of Titanium Nitride Neural Stimulating and Recording Electrodes as a Function of Film Thickness and Voltage Biasing. Annu Int Conf IEEE Eng Med Biol Soc 2021; 2021:6647-6650. [PMID: 34892632 DOI: 10.1109/embc46164.2021.9630715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Thin film titanium nitride (TiN), with a geometric surface area of 2,000 μm2, was deposited on planar test structures with thicknesses of 95, 185, 315, and 645 nm. Electrochemical measurements of electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and voltage transient (VT) were performed. We found that impedance values decreased and charge storage and charge injection capacities increased with increasing film thicknesses. Additionally, applying a anodic bias to TiN can increase the charge injection of the film to nearly double that of a non-biased film.
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20
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Chakraborty B, Joshi-Imre A, Cogan SF. Sputtered Ruthenium Oxide Neural Stimulation Electrodes . Annu Int Conf IEEE Eng Med Biol Soc 2021; 2021:6655-6658. [PMID: 34892634 DOI: 10.1109/embc46164.2021.9630483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We have investigated the charge-injection properties of sputtered ruthenium oxide (RuOx) coatings deposited on planar microelectrode arrays. Substantial charge was found to be available for injection within -0.6/0.6 V vs Ag|AgCl potential limits for the sputtered RuOx film. The charge-injection capacity increased further upon extending the potential limits to -0.7/0.7 V vs Ag|AgCl. No oxygen reduction, an unwanted side reaction, was observed during the pulsing of sputtered RuOx microelectrodes in phosphate buffered saline solution. Additionally, the RuOx coatings were found to be electrochemically stable for up to 1-billion-cycles of constant current stimulation pulsing at 8 nC/phase in model-ISF at 37° C.
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21
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Frederick RA, Troyk PR, Cogan SF. Effects of Varying Pulse Width and Frequency of Wireless Stimulation in Rat Sciatic Nerve. Annu Int Conf IEEE Eng Med Biol Soc 2021; 2021:6562-6564. [PMID: 34892612 PMCID: PMC10362914 DOI: 10.1109/embc46164.2021.9631070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Peripheral nerve stimulation is a commonly used method for assisting movements after spinal cord injury, stroke, traumatic brain injury, and other types of neurological damage or dysfunction. There are many different patterns of electrical stimulation used to accomplish movement. And so, our study investigated stimulation with a wireless floating microelectrode array (WFMA) in comparison to previously reported data on functional electrical stimulation. To determine the effect on hindlimb movement, we tested a range of frequencies and pulse widths using WFMAs that were implanted in the rat sciatic nerve for 38 weeks. Frequencies between 1 and 50 Hz did not change the minimum current amplitude required to elicit movement in the hindlimb. Increasing pulse width from 57.2 to 400.4 µs decreased the minimum current required but had an associated increase in total charge applied per pulse. Overall, the WFMA provides a stable wireless peripheral nerve interface suitable for functional electrical stimulation.Clinical Relevance- This work establishes the efficacy of various stimulation parameters for controlling movement with a wireless peripheral nerve stimulator.
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Frederick RA, Troyk PR, Cogan SF. Wireless microelectrode arrays for selective and chronically stable peripheral nerve stimulation for hindlimb movement. J Neural Eng 2021; 18:10.1088/1741-2552/ac2bb8. [PMID: 34592725 PMCID: PMC10685740 DOI: 10.1088/1741-2552/ac2bb8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 09/30/2021] [Indexed: 11/12/2022]
Abstract
Objective. Maximizing the stability of implanted neural interfaces will be critical to developing effective treatments for neurological and neuromuscular disorders. Our research aims to develop a stable neural interface using wireless communication and intrafascicular microelectrodes to provide highly selective stimulation of neural tissue.Approach. We implanted a wireless floating microelectrode array into the left sciatic nerve of six rats. Over a 38 week implantation period, we recorded stimulation thresholds and movements evoked at each implanted electrode. We also tracked each animal's response to sensory stimuli and performance on two different walking tasks.Main results. Presence of the microelectrode array inside the sciatic nerve did not cause any obvious motor or sensory deficits in the hindlimb. Visible movement in the hindlimb was evoked by stimulating the sciatic nerve with currents as low as 4.1µA. Thresholds for most of the 96 electrodes we implanted were below 20µA, and predictable recruitment of plantar flexion and dorsiflexion was achieved by stimulating rat sciatic nerve with the intrafascicular microelectrode array. Further, motor recruitment patterns for each electrode did not change significantly throughout the study.Significance. Incorporating wireless communication and a low-profile neural interface facilitated highly stable motor recruitment thresholds and fine motor control in the hindlimb throughout an extensive 9.5 month assessment in rodent peripheral nerve. Results of this study indicate that use of the wireless device tested here could be extended to other applications requiring selective neural stimulation and chronic implantation.
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Affiliation(s)
- Rebecca A Frederick
- Bioengineering Department, The University of Texas at Dallas, Richardson, TX, United States of America
| | - Philip R Troyk
- Biomedical Engineering Department, Illinois Institute of Technology, Chicago, IL, United States of America
| | - Stuart F Cogan
- Bioengineering Department, The University of Texas at Dallas, Richardson, TX, United States of America
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23
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Usoro JO, Dogra K, Abbott JR, Radhakrishna R, Cogan SF, Pancrazio JJ, Patnaik SS. Influence of Implantation Depth on the Performance of Intracortical Probe Recording Sites. Micromachines (Basel) 2021; 12:1158. [PMID: 34683209 PMCID: PMC8539313 DOI: 10.3390/mi12101158] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Revised: 09/18/2021] [Accepted: 09/24/2021] [Indexed: 02/06/2023]
Abstract
Microelectrode arrays (MEAs) enable the recording of electrical activity from cortical neurons which has implications for basic neuroscience and neuroprosthetic applications. The design space for MEA technology is extremely wide where devices may vary with respect to the number of monolithic shanks as well as placement of microelectrode sites. In the present study, we examine the differences in recording ability between two different MEA configurations: single shank (SS) and multi-shank (MS), both of which consist of 16 recording sites implanted in the rat motor cortex. We observed a significant difference in the proportion of active microelectrode sites over the 8-week indwelling period, in which SS devices exhibited a consistent ability to record activity, in contrast to the MS arrays which showed a marked decrease in activity within 2 weeks post-implantation. Furthermore, this difference was revealed to be dependent on the depth at which the microelectrode sites were located and may be mediated by anatomical heterogeneity, as well as the distribution of inhibitory neurons within the cortical layers. Our results indicate that the implantation depth of microelectrodes within the cortex needs to be considered relative to the chronic performance characterization.
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Affiliation(s)
| | | | | | | | | | - Joseph J. Pancrazio
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX 75080, USA; (J.O.U.); (K.D.); (J.R.A.); (R.R.); (S.F.C.); (S.S.P.)
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Ghazavi A, González-González MA, Romero-Ortega MI, Cogan SF. Intraneural ultramicroelectrode arrays for function-specific interfacing to the vagus nerve. Biosens Bioelectron 2020; 170:112608. [PMID: 33035896 PMCID: PMC7654841 DOI: 10.1016/j.bios.2020.112608] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 09/01/2020] [Accepted: 09/09/2020] [Indexed: 11/22/2022]
Abstract
Selective interfacing to small multifunctional nerves such as the vagus nerve (VN) which is the main multimodal autonomic nerve that provides a major communication pathway from vital peripheral organs to the brain, can have significant potential in treating and diagnosing diseases as well as enhancing our understanding of peripheral nerve circuits. Here we describe the fabrication of a 16-channel intraneural electrode array with ultramicro-dimensioned electrodes to achieve improved functionally selective recording. We demonstrate that the amorphous silicon carbide ultramicroelectrode arrays (a-SiC UMEAs) provide selectivity in the detection of neural activity in the cVN related to changes in systemic oxygenation and blood pressure. We will also demonstrate spatially selective recording of micro-compound action potentials (μCAPs) by electrical stimulation of the subdiaphragmatic branches of the VN. Distinct neural activity was recorded on electrodes separated by less than about 100 μm. This is the first time that this level of spatially selectivity recording has been demonstrated in the cVN with an intraneural multielectrode array.
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Affiliation(s)
- Atefeh Ghazavi
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, 75080, USA
| | | | - Mario I Romero-Ortega
- Department of Biomedical Engineering, University of Houston, Houston, TX, 77204, USA
| | - Stuart F Cogan
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, 75080, USA.
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Dousti B, Choi YI, Cogan SF, Lee GS. A High Energy Density 2D Microsupercapacitor Based on an Interconnected Network of a Horizontally Aligned Carbon Nanotube Sheet. ACS Appl Mater Interfaces 2020; 12:50011-50023. [PMID: 33100006 DOI: 10.1021/acsami.0c15319] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Highly aligned carbon nanotubes (HACNT sheets) have recently attracted great attention in developing high-performing ultrathin supercapacitors, which take advantage of the long-range alignment to improve electrochemical performance. While there are investigations into sandwich electrode CNT sheet devices, there are no known reports on interdigitated electrode (IDE) HACNT sheet microsupercapacitors (MSCs). This paper reports a facile method for rapidly fabricating high energy density ultrathin HACNT sheet-based MSCs with IDE planar configuration. Increasing the electrode thickness from 32 nm (5 layers) to 300 nm (50 layers) results in an approximately three times factor in performance. The 50 layer devices (MSC-50L) yield a top energy density of 10.52 mWhcm-3 and power density of 19.33 Wcm-3, making its performance comparable to those of microbatteries with potential for further improvement. Additionally, incorporation of MnO2 nanoparticles (NPs) within the MSCs-50L improves specific capacitance (242 Fcm-3), energy density (33.7 mWhcm-3), and power density (31 Wcm-3), outperforming current thin-film MSCs and matching the performance of 3D MSCs. MSCs also demonstrate a long cycle life (7000 charge-discharge cycles) with less than 5% capacitance fade. These findings suggest that HACNT sheets have substantial potential as active electrode materials for ultrathin high energy density microscale power sources.
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Affiliation(s)
- Behnoush Dousti
- Department of Electrical and Computer Engineering, The University of Texas at Dallas, 800 W Campbell Rd, Richardson, Texas, 75080, United States
| | - Ye Il Choi
- Department of Electrical and Computer Engineering, The University of Texas at Dallas, 800 W Campbell Rd, Richardson, Texas, 75080, United States
| | - Stuart F Cogan
- Department of Bioengineering, The University of Texas at Dallas, 800 W Campbell Rd, Richardson, Texas, 75080, United States
| | - Gil S Lee
- Department of Electrical and Computer Engineering, The University of Texas at Dallas, 800 W Campbell Rd, Richardson, Texas, 75080, United States
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26
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Shire DB, Gingerich MD, Wong PI, Skvarla M, Cogan SF, Chen J, Wang W, Rizzo JF. Micro-Fabrication of Components for a High-Density Sub-Retinal Visual Prosthesis. Micromachines (Basel) 2020; 11:mi11100944. [PMID: 33086504 PMCID: PMC7603138 DOI: 10.3390/mi11100944] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 10/10/2020] [Accepted: 10/13/2020] [Indexed: 01/30/2023]
Abstract
We present a retrospective of unique micro-fabrication problems and solutions that were encountered through over 10 years of retinal prosthesis product development, first for the Boston Retinal Implant Project initiated at the Massachusetts Institute of Technology and at Harvard Medical School’s teaching hospital, the Massachusetts Eye and Ear—and later at the startup company Bionic Eye Technologies, by some of the same personnel. These efforts culminated in the fabrication and assembly of 256+ channel visual prosthesis devices having flexible multi-electrode arrays that were successfully implanted sub-retinally in mini-pig animal models as part of our pre-clinical testing program. We report on the processing of the flexible multi-layered, planar and penetrating high-density electrode arrays, surgical tools for sub-retinal implantation, and other parts such as coil supports that facilitated the implantation of the peri-ocular device components. We begin with an overview of the implantable portion of our visual prosthesis system design, and describe in detail the micro-fabrication methods for creating the parts of our system that were assembled outside of our hermetically-sealed electronics package. We also note the unique surgical challenges that sub-retinal implantation of our micro-fabricated components presented, and how some of those issues were addressed through design, materials selection, and fabrication approaches.
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Affiliation(s)
- Douglas B. Shire
- Bionic Eye Technologies, Inc., Ithaca, NY 14850, USA; (M.D.G.); (P.I.W.)
- Correspondence: ; Tel.: +1-607-339-7085
| | | | - Patricia I. Wong
- Bionic Eye Technologies, Inc., Ithaca, NY 14850, USA; (M.D.G.); (P.I.W.)
| | - Michael Skvarla
- Cornell NanoScale Science and Technology Facility, Ithaca, NY 14853, USA;
| | - Stuart F. Cogan
- Department of Bioengineering, University of Texas, Dallas, Richardson, TX 75080, USA;
| | - Jinghua Chen
- Department of Ophthalmology, University of Florida, Gainesville, FL 32611, USA;
| | - Wei Wang
- Department of Ophthalmology, University of Louisville, Louisville, KY 40292, USA;
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Frederick RA, Meliane IY, Joshi-Imre A, Troyk PR, Cogan SF. Activated iridium oxide film (AIROF) electrodes for neural tissue stimulation. J Neural Eng 2020; 17:056001. [PMID: 32947268 DOI: 10.1088/1741-2552/abb9bf] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Iridium oxide films are commonly used as a high charge-injection electrode material in neural devices. Yet, few studies have performed in-depth assessments of material performance versus film thickness, especially for films grown on three-dimensional (instead of planar) metal surfaces in neutral pH electrolyte solutions. Further, few studies have investigated the driving voltage requirements for constant-current stimulation using activated iridium oxide (AIROF) electrodes, which will be a key constraint for future use in wirelessly powered neural devices. APPROACH In this study, iridium microwire probes were activated by repeated potential pulsing in room temperature phosphate buffered saline (pH 7.1-7.3). Electrochemical measurements were recorded in three different electrolyte conditions for probes with different geometric surface areas (GSAs) as the AIROF thickness was increased. MAIN RESULTS Maintaining an anodic potential bias during the inter-pulse interval was required for AIROF electrodes to deliver charge levels considered necessary for neural stimulation. Potential pulsing for 100-200 cycles was sufficient to achieve charge injection levels of 2.5 mC cm-2 (50 nC/phase in a biphasic pulse) in PBS with 2000 µm2 iridium probes. Increasing the electrode surface area to 3000 µm2 and 4000 µm2 significantly increased charge-injection capacity, reduced the driving voltage required to deliver a fixed amount of charge, and reduced polarization of the electrodes during constant-current pulsing. SIGNIFICANCE This study establishes methods for choosing an activation protocol and a desired GSA for three-dimensional iridium electrodes suitable for neural tissue insertion and stimulation, and provides guidelines for evaluating electrochemical performance of AIROF using model saline solutions.
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Affiliation(s)
- Rebecca A Frederick
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States of America
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Frederick RA, Margolis R, Hoyt K, Cogan SF. Evaluating Microelectrode Arrays in Peripheral Nerve Using Micro Computed Tomography .. Annu Int Conf IEEE Eng Med Biol Soc 2020; 2020:3432-3435. [PMID: 33018741 DOI: 10.1109/embc44109.2020.9176598] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Many advances have been made with imaging of implanted neural devices; however, the ability to image whole nerve samples remains limited. Further, few imaging modalities are well suited for visualizing both whole devices in vivo and individual microelectrodes within a nerve. In this study, we used micro-computed tomography (micro-CT) to evaluate Wireless Floating Microelectrode Arrays (WMFAs) implanted in rat sciatic nerve at the level of whole devices and individual electrodes. WFMAs were also used to track selective recruitment of plantar flexion and dorsiflexion of the rear paw, which was achieved by each implanted device (n=6) during chronic implantation. Evoked limb motion was correlated to end-of-study assessments using micro-CT to visualize electrode locations within the fascicular structure of the sciatic nerve. Results of this study show that micro-CT imaging can provide valuable assessments of microelectrode arrays implanted in peripheral nerves for both whole devices visualized in vivo and individual electrodes visualized in whole nerve tissue samples.Clinical relevance- This work informs the use of micro-computed tomography as a tool for correlating neural device performance with physical attributes of the implant location.
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Abstract
Chronic stability of functional performance is a significant challenge to the success of implantable devices for neural stimulation and recording. Integrating wireless technology with typical microelectrode array designs is one approach that may reduce instances of mechanical failure and improve the long-term performance of neural devices. We have investigated the long-term stability of Wireless Floating Microelectrode Arrays (WMFAs) implanted in rat sciatic nerve, and their ability to selectively recruit muscles in the hind limb via neural stimulation. Thresholds as low as 4.1 μA were able to generate visible motion of the rear paw. Each implanted device (n=6) was able to selectively recruit plantar flexion and dorsiflexion of the rear paw, and selective stimulation of both movements was achieved throughout the study period. The evoked limb motion was electrode specific and was dependent on location within the fascicular structure of the nerve. Motor thresholds and movement patterns remained stable for more than 8 weeks after device implantation. No major changes in limb function were observed between the implanted and contralateral limb, or between implanted animals and control group animals. The results of this study show that WFMAs with intrafascicular electrodes implanted in a healthy peripheral nerve can provide stable and selective motor recruitment, without altering overall limb function.
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Chakraborty B, Joshi-Imre A, Maeng J, Cogan SF. Sputtered ruthenium oxide coatings for neural stimulation and recording electrodes. J Biomed Mater Res B Appl Biomater 2020; 109:643-653. [PMID: 32945088 DOI: 10.1002/jbm.b.34728] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 08/17/2020] [Accepted: 09/02/2020] [Indexed: 12/28/2022]
Abstract
We have investigated the deposition and electrochemical properties of sputtered ruthenium oxide coatings for neural stimulation and recording electrodes. A combination of oxygen and water vapor was used as a reactive gas mixture during DC magnetron sputtering from a ruthenium metal target. The sputtering plasma was monitored by optical emission spectroscopy to determine the reactive species present and confirm the control of plasma chemistry by reactive gas flow rates into the deposition chamber. The effect of the O2 :H2 O gas ratio on the microstructure and electrochemical properties of the ruthenium oxide were studied in detail. We employed a combination of surface characterization techniques, including scanning electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy, to understand the relationship between plasma chemistry and the microstructure of the films produced under different gas flow conditions. Electrochemical characterization included cyclic voltammetry, electrochemical impedance spectroscopy, and voltage transient measurements, performed on planar ruthenium oxide electrodes with a geometric surface area of 1960 μm2 . At an O2 :H2 O gas flow rate ratio of 1:3, a cathodal charge-storage capacity per unit film thickness of 228.7 mC cm-2 μm-1 (median, Q1 = 134.5, Q3 = 236.6, n = 15) and a charge-injection capacity (0.6 V anodal interpulse bias) of 7.4 mC cm-2 (median, Q1 = 6.9, Q3 = 8.3, n = 15) were obtained in phosphate buffered saline. The charge-injection capacity of ruthenium oxide sputtered with water vapor in the reactive plasma is comparable with sputtered iridium oxide (SIROF) and higher than reported values for porous TiN, a commonly employed high-surface area stimulation electrode coating.
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Affiliation(s)
- Bitan Chakraborty
- Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas, USA
| | - Alexandra Joshi-Imre
- Cleanroom Research Laboratory, University of Texas at Dallas, Richardson, Texas, USA
| | - Jimin Maeng
- Department of Bioengineering, University of Texas at Dallas, Richardson, Texas, USA
| | - Stuart F Cogan
- Department of Bioengineering, University of Texas at Dallas, Richardson, Texas, USA
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Ghazavi A, Maeng J, Black M, Salvi S, Cogan SF. Electrochemical characteristics of ultramicro-dimensioned SIROF electrodes for neural stimulation and recording. J Neural Eng 2020; 17:016022. [PMID: 31665712 DOI: 10.1088/1741-2552/ab52ab] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
OBJECTIVE With ever increasing applications of neural recording and stimulation, the necessity for developing neural interfaces with higher selectivity and lower invasiveness is inevitable. Reducing the electrode size is one approach to achieving such goals. In this study, we investigated the effect of electrode geometric surface area (GSA), from 20 μm2 to 1960 μm2, on the electrochemical impedance and charge-injection properties of sputtered iridium oxide (SIROF) coated electrodes in response to current-pulsing typical of neural stimulation. These data were used to assess the electrochemical properties of ultra-small SIROF electrodes (GSA < 200 μm2) for stimulation and recording applications. APPROACH SIROF charge storage capacities (CSC), impedance, and charge-injection characteristics during current-pulsing of planar, circular electrodes were evaluated in an inorganic model of interstitial fluid (model-ISF). MAIN RESULTS SIROF electrodes as small as 20 μm2 could provide 1.3 nC/phase (200 μs pulse width, 0.6 V versus Ag|AgCl interpulse bias) of charge during current pulsing. The 1 kHz impedance of all electrodes used in this study were below 1 MΩ, which is suitable for neural recording. SIGNIFICANCE Ultra-small SIROF electrodes are capable of charge injection in buffered saline at levels above some reported thresholds for neural stimulation with microelectrodes.
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Affiliation(s)
- A Ghazavi
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States of America
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Atmaramani R, Chakraborty B, Rihani RT, Usoro J, Hammack A, Abbott J, Nnoromele P, Black BJ, Pancrazio JJ, Cogan SF. Ruthenium oxide based microelectrode arrays for in vitro and in vivo neural recording and stimulation. Acta Biomater 2020; 101:565-574. [PMID: 31678740 DOI: 10.1016/j.actbio.2019.10.040] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 10/22/2019] [Accepted: 10/28/2019] [Indexed: 10/25/2022]
Abstract
We have characterized the in vitro and in vivo extracellular neural recording and stimulation properties of ruthenium oxide (RuOx) based microelectrodes. Cytotoxicity and functional neurotoxicity assays were carried out to confirm the in vitro biocompatibility of RuOx. Material extract assays, in accordance to ISO protocol "10993-5: Biological evaluation of medical devices", revealed no significant effect on neuronal cell viability or the functional activity of cortical networks. In vitro microelectrode arrays (MEAs), with indium tin oxide (ITO) sites modified with sputtered iridium oxide (IrOx) and RuOx in a single array, were developed for a direct comparison of electrochemical and recording performance of RuOx to ITO and IrOx deposited microelectrode sites. The impedance of the RuOx-coated electrodes measured by electrochemical impedance spectroscopy was notably lower than that of ITO electrodes, resulting in robust extracellular recordings from cortical networks in vitro. We found comparable signal-to-noise ratios (SNRs) for RuOx and IrOx, both significantly higher than the SNR for ITO. RuOx-based MEAs were also fabricated and implanted in the rat motor cortex to demonstrate manufacturability of the RuOx processing and acute recording capabilities in vivo. We observed single-unit extracellular action potentials with a SNR >22, representing a first step for neurophysiological recordings in vivo with RuOx based microelectrodes. STATEMENT OF SIGNIFICANCE: A critical challenge in neural interface technology is the development of microelectrodes that have recording and electrical stimulation capabilities suitable for bidirectional communication between the external electronic device and the nervous system. The present study explores the feasibility and functional capabilities of ruthenium oxide microelectrodes as a neural interface. Significant improvement in electrochemical properties and neuronal recordings are reported when compared to commercially available indium tin oxide and was similar to that of iridium oxide electrodes. The data demonstrate the potential for future development of chronic neural interfaces using ruthenium oxide based microelectrodes for recording and stimulation.
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Usoro JO, Shih E, Black BJ, Rihani RT, Abbott J, Chakraborty B, Pancrazio JJ, Cogan SF. Chronic stability of local field potentials from standard and modified Blackrock microelectrode arrays implanted in the rat motor cortex. Biomed Phys Eng Express 2019. [DOI: 10.1088/2057-1976/ab4c02] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Deku F, Cohen Y, Joshi-Imre A, Kanneganti A, Gardner TJ, Cogan SF. Amorphous silicon carbide ultramicroelectrode arrays for neural stimulation and recording. J Neural Eng 2019; 15:016007. [PMID: 28952963 DOI: 10.1088/1741-2552/aa8f8b] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Foreign body response to indwelling cortical microelectrodes limits the reliability of neural stimulation and recording, particularly for extended chronic applications in behaving animals. The extent to which this response compromises the chronic stability of neural devices depends on many factors including the materials used in the electrode construction, the size, and geometry of the indwelling structure. Here, we report on the development of microelectrode arrays (MEAs) based on amorphous silicon carbide (a-SiC). APPROACH This technology utilizes a-SiC for its chronic stability and employs semiconductor manufacturing processes to create MEAs with small shank dimensions. The a-SiC films were deposited by plasma enhanced chemical vapor deposition and patterned by thin-film photolithographic techniques. To improve stimulation and recording capabilities with small contact areas, we investigated low impedance coatings on the electrode sites. The assembled devices were characterized in phosphate buffered saline for their electrochemical properties. MAIN RESULTS MEAs utilizing a-SiC as both the primary structural element and encapsulation were fabricated successfully. These a-SiC MEAs had 16 penetrating shanks. Each shank has a cross-sectional area less than 60 µm2 and electrode sites with a geometric surface area varying from 20 to 200 µm2. Electrode coatings of TiN and SIROF reduced 1 kHz electrode impedance to less than 100 kΩ from ~2.8 MΩ for 100 µm2 Au electrode sites and increased the charge injection capacities to values greater than 3 mC cm-2. Finally, we demonstrated functionality by recording neural activity from basal ganglia nucleus of Zebra Finches and motor cortex of rat. SIGNIFICANCE The a-SiC MEAs provide a significant advancement in the development of microelectrodes that over the years has relied on silicon platforms for device manufacture. These flexible a-SiC MEAs have the potential for decreased tissue damage and reduced foreign body response. The technique is promising and has potential for clinical translation and large scale manufacturing.
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Affiliation(s)
- Felix Deku
- Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080, United States of America
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Maeng J, Chakraborty B, Geramifard N, Kang T, Rihani RT, Joshi-Imre A, Cogan SF. High-charge-capacity sputtered iridium oxide neural stimulation electrodes deposited using water vapor as a reactive plasma constituent. J Biomed Mater Res B Appl Biomater 2019; 108:880-891. [PMID: 31353822 DOI: 10.1002/jbm.b.34442] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 06/06/2019] [Accepted: 06/28/2019] [Indexed: 11/07/2022]
Abstract
The deposition and properties of sputtered iridium oxide films (SIROFs) using water vapor as a reactive gas constituent are investigated for their potential as high-charge-capacity neural stimulation electrodes. Systematic investigation through a series of optical and electrochemical measurements reveals that the incorporation of water vapor as a reactive gas constituent, along with oxygen, alters the reduction-oxidation (redox) state of the plasma as well as its morphology and the electrochemical characteristics, including the cathodal charge-storage capacity (CSCc ) and charge-injection capacity (CIC), of the SIROF. An apparent optimal O2 :H2 O gas ratio of 1:3 produced SIROF with a CSCc of 182.0 mC cm-2 μm-1 (median, Q1 = 172.5, Q3 = 193.4, n = 15) and a CIC of 3.57 mC cm-2 (median, Q1 = 2.97, Q3 = 4.58, n = 12) for 300-nm-thick films. These values are higher than those obtained with SIROFs deposited using no water vapor by a factor of 2.3 and 1.7 for the CSCc and CIC, respectively. Additionally, the SIROF showed minimal changes in electrochemical characteristics over 109 pulses of constant current stimulation and showed no indication of cytotoxicity toward primary cortical neurons in a cell viability assay. These results warrant investigation of the chronic recording and stimulation capabilities of the SIROF for implantable microelectrode arrays.
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Affiliation(s)
- Jimin Maeng
- Department of Bioengineering, University of Texas at Dallas, Richardson, Texas
| | - Bitan Chakraborty
- Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas
| | - Negar Geramifard
- Department of Bioengineering, University of Texas at Dallas, Richardson, Texas
| | - Tong Kang
- Department of Mechanical Engineering, University of Texas at Dallas, Richardson, Texas
| | - Rashed T Rihani
- Department of Bioengineering, University of Texas at Dallas, Richardson, Texas
| | - Alexandra Joshi-Imre
- Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas
| | - Stuart F Cogan
- Department of Bioengineering, University of Texas at Dallas, Richardson, Texas
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Pancrazio JJ, Cogan SF. Editorial for the Special Issue on Neural Electrodes: Design and Applications. Micromachines (Basel) 2019; 10:mi10070466. [PMID: 31336980 PMCID: PMC6680485 DOI: 10.3390/mi10070466] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 07/09/2019] [Indexed: 12/14/2022]
Affiliation(s)
- Joseph J Pancrazio
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, BSB 13.633, Richardson, TX 75080, USA.
| | - Stuart F Cogan
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, BSB 13.633, Richardson, TX 75080, USA.
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Joshi-Imre A, Black BJ, Abbott J, Kanneganti A, Rihani R, Chakraborty B, Danda VR, Maeng J, Sharma R, Rieth L, Negi S, Pancrazio JJ, Cogan SF. Chronic recording and electrochemical performance of amorphous silicon carbide-coated Utah electrode arrays implanted in rat motor cortex. J Neural Eng 2019; 16:046006. [DOI: 10.1088/1741-2552/ab1bc8] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Hernandez-Reynoso AG, Nandam S, O’Brien JM, Kanneganti A, Cogan SF, Freeman DK, Romero-Ortega MI. Miniature electroparticle-cuff for wireless peripheral neuromodulation. J Neural Eng 2019; 16:046002. [DOI: 10.1088/1741-2552/ab1c36] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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González-González MA, Kanneganti A, Joshi-Imre A, Hernandez-Reynoso AG, Bendale G, Modi R, Ecker M, Khurram A, Cogan SF, Voit WE, Romero-Ortega MI. Thin Film Multi-Electrode Softening Cuffs for Selective Neuromodulation. Sci Rep 2018; 8:16390. [PMID: 30401906 PMCID: PMC6219541 DOI: 10.1038/s41598-018-34566-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 10/18/2018] [Indexed: 01/21/2023] Open
Abstract
Silicone nerve cuff electrodes are commonly implanted on relatively large and accessible somatic nerves as peripheral neural interfaces. While these cuff electrodes are soft (1–50 MPa), their self-closing mechanism requires of thick walls (200–600 µm), which in turn contribute to fibrotic tissue growth around and inside the device, compromising the neural interface. We report the use of thiol-ene/acrylate shape memory polymer (SMP) for the fabrication of thin film multi-electrode softening cuffs (MSC). We fabricated multi-size MSC with eight titanium nitride (TiN) electrodes ranging from 1.35 to 13.95 × 10−4 cm2 (1–3 kΩ) and eight smaller gold (Au) electrodes (3.3 × 10−5 cm2; 750 kΩ), that soften at physiological conditions to a modulus of 550 MPa. While the SMP material is not as soft as silicone, the flexural forces of the SMP cuff are about 70–700 times lower in the MSC devices due to the 30 μm thick film compared to the 600 μm thick walls of the silicone cuffs. We demonstrated the efficacy of the MSC to record neural signals from rat sciatic and pelvic nerves (1000 µm and 200 µm diameter, respectively), and the selective fascicular stimulation by current steering. When implanted side-by-side and histologically compared 30 days thereafter, the MSC devices showed significantly less inflammation, indicated by a 70–80% reduction in ED1 positive macrophages, and 54–56% less fibrotic vimentin immunoreactivity. Together, the data supports the use of MSC as compliant and adaptable technology for the interfacing of somatic and autonomic peripheral nerves.
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Affiliation(s)
- María A González-González
- Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA
| | - Aswini Kanneganti
- Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA
| | - Alexandra Joshi-Imre
- Department of Material Science and Engineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA
| | - Ana G Hernandez-Reynoso
- Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA
| | - Geetanjali Bendale
- Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA
| | - Romil Modi
- Department of Material Science and Engineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA
| | - Melanie Ecker
- Department of Material Science and Engineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA
| | - Ali Khurram
- Department of Material Science and Engineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA
| | - Stuart F Cogan
- Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA
| | - Walter E Voit
- Department of Material Science and Engineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA
| | - Mario I Romero-Ortega
- Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA.
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Deku F, Mohammed S, Joshi-Imre A, Maeng J, Danda V, Gardner TJ, Cogan SF. Effect of oxidation on intrinsic residual stress in amorphous silicon carbide films. J Biomed Mater Res B Appl Biomater 2018; 107:1654-1661. [PMID: 30321479 DOI: 10.1002/jbm.b.34258] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 08/26/2018] [Accepted: 09/16/2018] [Indexed: 11/11/2022]
Abstract
The change in residual stress in plasma enhanced chemical vapor deposition amorphous silicon carbide (a-SiC:H) films exposed to air and wet ambient environments is investigated. A close relationship between stress change and deposition condition is identified from mechanical and chemical characterization of a-SiC:H films. Evidence of amorphous silicon carbide films reacting with oxygen and water vapor in the ambient environment are presented. The effect of deposition parameters on oxidation and stress variation in a-SiC:H film is studied. It is found that the films deposited at low temperature or power are susceptible to oxidation and undergo a notable increase in compressive stress over time. Furthermore, the films deposited at sufficiently high temperature (≥325 C) and power density (≥0.2 W cm-2 ) do not exhibit pronounced oxidation or temporal stress variation. These results serve as the basis for developing amorphous silicon carbide based dielectric encapsulation for implantable medical devices. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1654-1661, 2019.
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Affiliation(s)
- Felix Deku
- Department of Bioengineering, University of Texas at Dallas, Richardson, Texas
| | - Shakil Mohammed
- Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas
| | | | - Jimin Maeng
- Department of Bioengineering, University of Texas at Dallas, Richardson, Texas
| | - Vindhya Danda
- Department of Bioengineering, University of Texas at Dallas, Richardson, Texas
| | - Timothy J Gardner
- Department of Biology and Department of Biomedical Engineering, Boston University, Boston, Massachusetts
| | - Stuart F Cogan
- Department of Bioengineering, University of Texas at Dallas, Richardson, Texas
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Deku F, Frewin CL, Stiller A, Cohen Y, Aqeel S, Joshi-Imre A, Black B, Gardner TJ, Pancrazio JJ, Cogan SF. Amorphous Silicon Carbide Platform for Next Generation Penetrating Neural Interface Designs. Micromachines (Basel) 2018; 9:E480. [PMID: 30424413 PMCID: PMC6215182 DOI: 10.3390/mi9100480] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/09/2018] [Accepted: 09/17/2018] [Indexed: 11/16/2022]
Abstract
Microelectrode arrays that consistently and reliably record and stimulate neural activity under conditions of chronic implantation have so far eluded the neural interface community due to failures attributed to both biotic and abiotic mechanisms. Arrays with transverse dimensions of 10 µm or below are thought to minimize the inflammatory response; however, the reduction of implant thickness also decreases buckling thresholds for materials with low Young's modulus. While these issues have been overcome using stiffer, thicker materials as transport shuttles during implantation, the acute damage from the use of shuttles may generate many other biotic complications. Amorphous silicon carbide (a-SiC) provides excellent electrical insulation and a large Young's modulus, allowing the fabrication of ultrasmall arrays with increased resistance to buckling. Prototype a-SiC intracortical implants were fabricated containing 8 - 16 single shanks which had critical thicknesses of either 4 µm or 6 µm. The 6 µm thick a-SiC shanks could penetrate rat cortex without an insertion aid. Single unit recordings from SIROF-coated arrays implanted without any structural support are presented. This work demonstrates that a-SiC can provide an excellent mechanical platform for devices that penetrate cortical tissue while maintaining a critical thickness less than 10 µm.
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Affiliation(s)
- Felix Deku
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Christopher L Frewin
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Allison Stiller
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Yarden Cohen
- Department of Biology and Biomedical Engineering, Boston University, Boston, MA 02215, USA.
| | - Saher Aqeel
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Alexandra Joshi-Imre
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Bryan Black
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Timothy J Gardner
- Department of Biology and Biomedical Engineering, Boston University, Boston, MA 02215, USA.
| | - Joseph J Pancrazio
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Stuart F Cogan
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA.
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Stiller AM, Black BJ, Kung C, Ashok A, Cogan SF, Varner VD, Pancrazio JJ. A Meta-Analysis of Intracortical Device Stiffness and Its Correlation with Histological Outcomes. Micromachines (Basel) 2018; 9:E443. [PMID: 30424376 PMCID: PMC6187651 DOI: 10.3390/mi9090443] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 08/23/2018] [Accepted: 08/30/2018] [Indexed: 01/22/2023]
Abstract
Neural implants offer solutions for a variety of clinical issues. While commercially available devices can record neural signals for short time periods, they fail to do so chronically, partially due to the sustained tissue response around the device. Our objective was to assess the correlation between device stiffness, a function of both material modulus and cross-sectional area, and the severity of immune response. Meta-analysis data were derived from nine previously published studies which reported device material and geometric properties, as well as histological outcomes. Device bending stiffness was calculated by treating the device shank as a cantilevered beam. Immune response was quantified through analysis of immunohistological images from each study, specifically looking at fluorescent markers for neuronal nuclei and astrocytes, to assess neuronal dieback and gliosis. Results demonstrate that the severity of the immune response, within the first 50 µm of the device, is highly correlated with device stiffness, as opposed to device modulus or cross-sectional area independently. In general, commercially available devices are around two to three orders of magnitude higher in stiffness than devices which induced a minimal tissue response. These results have implications for future device designs aiming to decrease chronic tissue response and achieve increased long-term functionality.
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Affiliation(s)
- Allison M Stiller
- Department of Bioengineering, The University of Texas at Dallas, 800W. Campbell Rd., Richardson, TX 75080, USA.
| | - Bryan J Black
- Department of Bioengineering, The University of Texas at Dallas, 800W. Campbell Rd., Richardson, TX 75080, USA.
| | - Christopher Kung
- Department of Bioengineering, The University of Texas at Dallas, 800W. Campbell Rd., Richardson, TX 75080, USA.
| | - Aashika Ashok
- Department of Bioengineering, The University of Texas at Dallas, 800W. Campbell Rd., Richardson, TX 75080, USA.
| | - Stuart F Cogan
- Department of Bioengineering, The University of Texas at Dallas, 800W. Campbell Rd., Richardson, TX 75080, USA.
| | - Victor D Varner
- Department of Bioengineering, The University of Texas at Dallas, 800W. Campbell Rd., Richardson, TX 75080, USA.
| | - Joseph J Pancrazio
- Department of Bioengineering, The University of Texas at Dallas, 800W. Campbell Rd., Richardson, TX 75080, USA.
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Black BJ, Kanneganti A, Joshi-Imre A, Rihani R, Chakraborty B, Abbott J, Pancrazio JJ, Cogan SF. Chronic recording and electrochemical performance of Utah microelectrode arrays implanted in rat motor cortex. J Neurophysiol 2018; 120:2083-2090. [PMID: 30020844 DOI: 10.1152/jn.00181.2018] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Multisite implantable electrode arrays serve as a tool to understand cortical network connectivity and plasticity. Furthermore, they enable electrical stimulation to drive plasticity, study motor/sensory mapping, or provide network input for controlling brain-computer interfaces. Neurobehavioral rodent models are prevalent in studies of motor cortex injury and recovery as well as restoration of auditory/visual cues due to their relatively low cost and ease of training. Therefore, it is important to understand the chronic performance of relevant electrode arrays in rodent models. In this report, we evaluate the chronic recording and electrochemical performance of 16-channel Utah electrode arrays, the current state-of-the-art in pre-/clinical cortical recording and stimulation, in rat motor cortex over a period of 6 mo. The single-unit active electrode yield decreased from 52.8 ± 10.0 ( week 1) to 13.4 ± 5.1% ( week 24). Similarly, the total number of single units recorded on all electrodes across all arrays decreased from 106 to 15 over the same time period. Parallel measurements of electrochemical impedance spectra and cathodic charge storage capacity exhibited significant changes in electrochemical characteristics consistent with development of electrolyte leakage pathways over time. Additionally, measurements of maximum cathodal potential excursion indicated that only a relatively small fraction of electrodes (10-35% at 1 and 24 wk postimplantation) were capable of delivering relevant currents (20 µA at 4 nC/ph) without exceeding negative or positive electrochemical potential limits. In total, our findings suggest mainly abiotic failure modes, including mechanical wire breakage as well as degradation of conducting and insulating substrates. NEW & NOTEWORTHY Multisite implantable electrode arrays serve as a tool to record cortical network activity and enable electrical stimulation to drive plasticity or provide network feedback. The use of rodent models in these fields is prevalent. We evaluated chronic recording and electrochemical performance of 16-channel Utah electrode arrays in rat motor cortex over a period of 6 mo. We primarily observed abiotic failure modes suggestive of mechanical wire breakage and/or degradation of insulation.
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Affiliation(s)
- Bryan J Black
- Department of Bioengineering, The University of Texas at Dallas , Richardson, Texas
| | - Aswini Kanneganti
- Department of Bioengineering, The University of Texas at Dallas , Richardson, Texas
| | - Alexandra Joshi-Imre
- Department of Bioengineering, The University of Texas at Dallas , Richardson, Texas
| | - Rashed Rihani
- Department of Bioengineering, The University of Texas at Dallas , Richardson, Texas
| | - Bitan Chakraborty
- Department of Bioengineering, The University of Texas at Dallas , Richardson, Texas
| | - Justin Abbott
- Department of Bioengineering, The University of Texas at Dallas , Richardson, Texas
| | - Joseph J Pancrazio
- Department of Bioengineering, The University of Texas at Dallas , Richardson, Texas
| | - Stuart F Cogan
- Department of Bioengineering, The University of Texas at Dallas , Richardson, Texas
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Ghazavi A, Cogan SF. Electrochemical characterization of high frequency stimulation electrodes: role of electrode material and stimulation parameters on electrode polarization. J Neural Eng 2018; 15:036023. [DOI: 10.1088/1741-2552/aa9f31] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Pancrazio JJ, Deku F, Ghazavi A, Stiller AM, Rihani R, Frewin CL, Varner VD, Gardner TJ, Cogan SF. Thinking Small: Progress on Microscale Neurostimulation Technology. Neuromodulation 2017; 20:745-752. [PMID: 29076214 PMCID: PMC5943060 DOI: 10.1111/ner.12716] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 08/28/2017] [Accepted: 09/19/2017] [Indexed: 01/08/2023]
Abstract
OBJECTIVES Neural stimulation is well-accepted as an effective therapy for a wide range of neurological disorders. While the scale of clinical devices is relatively large, translational, and pilot clinical applications are underway for microelectrode-based systems. Microelectrodes have the advantage of stimulating a relatively small tissue volume which may improve selectivity of therapeutic stimuli. Current microelectrode technology is associated with chronic tissue response which limits utility of these devices for neural recording and stimulation. One approach for addressing the tissue response problem may be to reduce physical dimensions of the device. "Thinking small" is a trend for the electronics industry, and for implantable neural interfaces, the result may be a device that can evade the foreign body response. MATERIALS AND METHODS This review paper surveys our current understanding pertaining to the relationship between implant size and tissue response and the state-of-the-art in ultrasmall microelectrodes. A comprehensive literature search was performed using PubMed, Web of Science (Clarivate Analytics), and Google Scholar. RESULTS The literature review shows recent efforts to create microelectrodes that are extremely thin appear to reduce or even eliminate the chronic tissue response. With high charge capacity coatings, ultramicroelectrodes fabricated from emerging polymers, and amorphous silicon carbide appear promising for neurostimulation applications. CONCLUSION We envision the emergence of robust and manufacturable ultramicroelectrodes that leverage advanced materials where the small cross-sectional geometry enables compliance within tissue. Nevertheless, future testing under in vivo conditions is particularly important for assessing the stability of thin film devices under chronic stimulation.
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Affiliation(s)
- Joseph J. Pancrazio
- Department of Bioengineering, 800 W. Campbell Road, BSB 13.633, The University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Felix Deku
- Department of Bioengineering, 800 W. Campbell Road, BSB 13.633, The University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Atefeh Ghazavi
- Department of Bioengineering, 800 W. Campbell Road, BSB 13.633, The University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Allison M. Stiller
- Department of Bioengineering, 800 W. Campbell Road, BSB 13.633, The University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Rashed Rihani
- Department of Bioengineering, 800 W. Campbell Road, BSB 13.633, The University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Christopher L. Frewin
- Department of Bioengineering, 800 W. Campbell Road, BSB 13.633, The University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Victor D. Varner
- Department of Bioengineering, 800 W. Campbell Road, BSB 13.633, The University of Texas at Dallas, Richardson, TX, 75080, USA
| | | | - Stuart F. Cogan
- Department of Bioengineering, 800 W. Campbell Road, BSB 13.633, The University of Texas at Dallas, Richardson, TX, 75080, USA
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Freeman DK, O'Brien JM, Kumar P, Daniels B, Irion RA, Shraytah L, Ingersoll BK, Magyar AP, Czarnecki A, Wheeler J, Coppeta JR, Abban MP, Gatzke R, Fried SI, Lee SW, Duwel AE, Bernstein JJ, Widge AS, Hernandez-Reynoso A, Kanneganti A, Romero-Ortega MI, Cogan SF. A Sub-millimeter, Inductively Powered Neural Stimulator. Front Neurosci 2017; 11:659. [PMID: 29230164 PMCID: PMC5712043 DOI: 10.3389/fnins.2017.00659] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 11/10/2017] [Indexed: 01/02/2023] Open
Abstract
Wireless neural stimulators are being developed to address problems associated with traditional lead-based implants. However, designing wireless stimulators on the sub-millimeter scale (<1 mm3) is challenging. As device size shrinks, it becomes difficult to deliver sufficient wireless power to operate the device. Here, we present a sub-millimeter, inductively powered neural stimulator consisting only of a coil to receive power, a capacitor to tune the resonant frequency of the receiver, and a diode to rectify the radio-frequency signal to produce neural excitation. By replacing any complex receiver circuitry with a simple rectifier, we have reduced the required voltage levels that are needed to operate the device from 0.5 to 1 V (e.g., for CMOS) to ~0.25–0.5 V. This reduced voltage allows the use of smaller receive antennas for power, resulting in a device volume of 0.3–0.5 mm3. The device was encapsulated in epoxy, and successfully passed accelerated lifetime tests in 80°C saline for 2 weeks. We demonstrate a basic proof-of-concept using stimulation with tens of microamps of current delivered to the sciatic nerve in rat to produce a motor response.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | - Shelley I Fried
- Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Seung Woo Lee
- Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | | | | | - Alik S Widge
- Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States.,Picower Institute of Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, United States
| | | | - Aswini Kanneganti
- Department of Bioengineering, University of Texas, Richardson, TX, United States
| | | | - Stuart F Cogan
- Department of Bioengineering, University of Texas, Richardson, TX, United States
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Knaack GL, McHail DG, Borda G, Koo B, Peixoto N, Cogan SF, Dumas TC, Pancrazio JJ. In vivo Characterization of Amorphous Silicon Carbide As a Biomaterial for Chronic Neural Interfaces. Front Neurosci 2016; 10:301. [PMID: 27445672 PMCID: PMC4923247 DOI: 10.3389/fnins.2016.00301] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2016] [Accepted: 06/15/2016] [Indexed: 11/13/2022] Open
Abstract
Implantable microelectrode arrays (MEAs) offer clinical promise for prosthetic devices by enabling restoration of communication and control of artificial limbs. While proof-of-concept recordings from MEAs have been promising, work in animal models demonstrates that the obtained signals degrade over time. Both material robustness and tissue response are acknowledged to have a role in device lifetime. Amorphous Silicon carbide (a-SiC), a robust material that is corrosion resistant, has emerged as an alternative encapsulation layer for implantable devices. We systematically examined the impact of a-SiC coating on Si probes by immunohistochemical characterization of key markers implicated in tissue-device response. After implantation, we performed device capture immunohistochemical labeling of neurons, astrocytes, and activated microglia/macrophages after 4 and 8 weeks of implantation. Neuron loss and microglia activation were similar between Si and a-SiC coated probes, while tissue implanted with a-SiC displayed a reduction in astrocytes adjacent to the probe. These results suggest that a-SiC has a similar biocompatibility profile as Si, and may be suitable for implantable MEA applications as a hermetic coating to prevent material degradation.
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Affiliation(s)
- Gretchen L Knaack
- Department of Molecular Neuroscience, Krasnow Institute for Advanced Study, George Mason UniversityFairfax, VA, USA; Quantitative Scientific SolutionsArlington, VA, USA
| | - Daniel G McHail
- Department of Molecular Neuroscience, Krasnow Institute for Advanced Study, George Mason University Fairfax, VA, USA
| | - German Borda
- Department of Bioengineering, George Mason University Fairfax, VA, USA
| | - Beomseo Koo
- Department of Bioengineering, George Mason University Fairfax, VA, USA
| | - Nathalia Peixoto
- Electrical and Computer Engineering Department, George Mason University Fairfax, VA, USA
| | - Stuart F Cogan
- Department of Bioengineering, University of Texas at Dallas Richardson, TX, USA
| | - Theodore C Dumas
- Department of Molecular Neuroscience, Krasnow Institute for Advanced Study, George Mason University Fairfax, VA, USA
| | - Joseph J Pancrazio
- Quantitative Scientific SolutionsArlington, VA, USA; Department of Bioengineering, University of Texas at DallasRichardson, TX, USA
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Abstract
OBJECTIVE Recent initiatives in bioelectronic modulation of the nervous system by the NIH (SPARC), DARPA (ElectRx, SUBNETS) and the GlaxoSmithKline Bioelectronic Medicines effort are ushering in a new era of therapeutic electrical stimulation. These novel therapies are prompting a re-evaluation of established electrical thresholds for stimulation-induced tissue damage. APPROACH In this review, we explore what is known and unknown in published literature regarding tissue damage from electrical stimulation. MAIN RESULTS For macroelectrodes, the potential for tissue damage is often assessed by comparing the intensity of stimulation, characterized by the charge density and charge per phase of a stimulus pulse, with a damage threshold identified through histological evidence from in vivo experiments as described by the Shannon equation. While the Shannon equation has proved useful in assessing the likely occurrence of tissue damage, the analysis is limited by the experimental parameters of the original studies. Tissue damage is influenced by factors not explicitly incorporated into the Shannon equation, including pulse frequency, duty cycle, current density, and electrode size. Microelectrodes in particular do not follow the charge per phase and charge density co-dependence reflected in the Shannon equation. The relevance of these factors to tissue damage is framed in the context of available reports from modeling and in vivo studies. SIGNIFICANCE It is apparent that emerging applications, especially with microelectrodes, will require clinical charge densities that exceed traditional damage thresholds. Experimental data show that stimulation at higher charge densities can be achieved without causing tissue damage, suggesting that safety parameters for microelectrodes might be distinct from those defined for macroelectrodes. However, these increased charge densities may need to be justified by bench, non-clinical or clinical testing to provide evidence of device safety.
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Affiliation(s)
- Stuart F Cogan
- The Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA
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Cogan SF, Ehrlich J, Plante TD. The effect of electrode geometry on electrochemical properties measured in saline. Annu Int Conf IEEE Eng Med Biol Soc 2015; 2014:6850-3. [PMID: 25571570 DOI: 10.1109/embc.2014.6945202] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The impedance, cyclic voltammetry, and charge-injection properties of rectangular, sputtered iridium oxide (SIROF) electrodes have been measured in buffered physiological saline over a range of geometric surface areas (GSA) and perimeter-to-area ratios (P/A). Electrodes with a higher P/A are expected to have a lower impedance and higher charge injection capacity (Q(inj)), and both these effects were evident for SIROF electrodes with a GSA in the range 0.0023-0.0031 mm(2). However, the magnitude of the effect was modest. The increase in Q(inj) for rectangular electrodes with a P/A ranging from 94 to 255 mm(-1) was 21-26% depending on pulse width. There was a corresponding decrease in impedance (0.1 to 10(5) Hz) with increasing P/A and an increase in the SIROF charge storage capacity calculated from cyclic voltammetry. To assess the full usefulness of high P/A electrodes for increasing the reversible Q(inj) of an electrode, measurements should now be extended to chronic in vivo preparations.
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