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Li H, Tan P, Rao Y, Bhattacharya S, Wang Z, Kim S, Gangopadhyay S, Shi H, Jankovic M, Huh H, Li Z, Maharjan P, Wells J, Jeong H, Jia Y, Lu N. E-Tattoos: Toward Functional but Imperceptible Interfacing with Human Skin. Chem Rev 2024; 124:3220-3283. [PMID: 38465831 DOI: 10.1021/acs.chemrev.3c00626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
The human body continuously emits physiological and psychological information from head to toe. Wearable electronics capable of noninvasively and accurately digitizing this information without compromising user comfort or mobility have the potential to revolutionize telemedicine, mobile health, and both human-machine or human-metaverse interactions. However, state-of-the-art wearable electronics face limitations regarding wearability and functionality due to the mechanical incompatibility between conventional rigid, planar electronics and soft, curvy human skin surfaces. E-Tattoos, a unique type of wearable electronics, are defined by their ultrathin and skin-soft characteristics, which enable noninvasive and comfortable lamination on human skin surfaces without causing obstruction or even mechanical perception. This review article offers an exhaustive exploration of e-tattoos, accounting for their materials, structures, manufacturing processes, properties, functionalities, applications, and remaining challenges. We begin by summarizing the properties of human skin and their effects on signal transmission across the e-tattoo-skin interface. Following this is a discussion of the materials, structural designs, manufacturing, and skin attachment processes of e-tattoos. We classify e-tattoo functionalities into electrical, mechanical, optical, thermal, and chemical sensing, as well as wound healing and other treatments. After discussing energy harvesting and storage capabilities, we outline strategies for the system integration of wireless e-tattoos. In the end, we offer personal perspectives on the remaining challenges and future opportunities in the field.
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Affiliation(s)
- Hongbian Li
- Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Philip Tan
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Yifan Rao
- Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Sarnab Bhattacharya
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Zheliang Wang
- Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Sangjun Kim
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Susmita Gangopadhyay
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Hongyang Shi
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Matija Jankovic
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Heeyong Huh
- Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Zhengjie Li
- Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Pukar Maharjan
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Jonathan Wells
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Hyoyoung Jeong
- Department of Electrical and Computer Engineering, University of California Davis, Davis, California 95616, United States
| | - Yaoyao Jia
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Nanshu Lu
- Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, Texas 78712, United States
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
- Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States
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Muguet I, Maziz A, Mathieu F, Mazenq L, Larrieu G. Combining PEDOT:PSS Polymer Coating with Metallic 3D Nanowires Electrodes to Achieve High Electrochemical Performances for Neuronal Interfacing Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2302472. [PMID: 37385261 DOI: 10.1002/adma.202302472] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 05/18/2023] [Accepted: 05/26/2023] [Indexed: 07/01/2023]
Abstract
This study presents a novel approach to improve the performance of microelectrode arrays (MEAs) used for electrophysiological studies of neuronal networks. The integration of 3D nanowires (NWs) with MEAs increases the surface-to-volume ratio, which enables subcellular interactions and high-resolution neuronal signal recording. However, these devices suffer from high initial interface impedance and limited charge transfer capacity due to their small effective area. To overcome these limitations, the integration of conductive polymer coatings, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) is investigated as a mean of improving the charge transfer capacity and biocompatibility of MEAs. The study combines platinum silicide-based metallic 3D nanowires electrodes with electrodeposited PEDOT:PSS coatings to deposit ultra-thin (<50 nm) layers of conductive polymer onto metallic electrodes with very high selectivity. The polymer-coated electrodes were fully characterized electrochemically and morphologically to establish a direct relationship between synthesis conditions, morphology, and conductive features. Results show that PEDOT-coated electrodes exhibit thickness-dependent improved stimulation and recording performances, offering new perspectives for neuronal interfacing with optimal cell engulfment to enable the study of neuronal activity with acute spatial and signal resolution at the sub-cellular level.
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Affiliation(s)
- Ines Muguet
- LAAS-CNRS, Université de Toulouse, CNRS, 7 avenue du colonel Roche, Toulouse, F-31400, France
| | - Ali Maziz
- LAAS-CNRS, Université de Toulouse, CNRS, 7 avenue du colonel Roche, Toulouse, F-31400, France
| | - Fabrice Mathieu
- LAAS-CNRS, Université de Toulouse, CNRS, 7 avenue du colonel Roche, Toulouse, F-31400, France
| | - Laurent Mazenq
- LAAS-CNRS, Université de Toulouse, CNRS, 7 avenue du colonel Roche, Toulouse, F-31400, France
| | - Guilhem Larrieu
- LAAS-CNRS, Université de Toulouse, CNRS, 7 avenue du colonel Roche, Toulouse, F-31400, France
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Lam CM, Latif U, Sack A, Govindan S, Sanderson M, Vu DT, Smith G, Sayed D, Khan T. Advances in Spinal Cord Stimulation. Bioengineering (Basel) 2023; 10:185. [PMID: 36829678 PMCID: PMC9951889 DOI: 10.3390/bioengineering10020185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 01/17/2023] [Accepted: 01/30/2023] [Indexed: 02/04/2023] Open
Abstract
Neuromodulation, specifically spinal cord stimulation (SCS), has become a staple of chronic pain management for various conditions including failed back syndrome, chronic regional pain syndrome, refractory radiculopathy, and chronic post operative pain. Since its conceptualization, it has undergone several advances to increase safety and convenience for patients and implanting physicians. Current research and efforts are aimed towards novel programming modalities and modifications of existing hardware. Here we review the recent advances and future directions in spinal cord stimulation including a brief review of the history of SCS, SCS waveforms, new materials for SCS electrodes (including artificial skins, new materials, and injectable electrodes), closed loop systems, and neurorestorative devices.
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Affiliation(s)
- Christopher M. Lam
- Department of Anesthesiology and Pain Medicine, University of Kansas Health System, Kansas City, KS 66160, USA
| | - Usman Latif
- Department of Anesthesiology and Pain Medicine, University of Kansas Health System, Kansas City, KS 66160, USA
| | - Andrew Sack
- Department of Anesthesiology and Pain Medicine, University of Kansas Health System, Kansas City, KS 66160, USA
| | - Susheel Govindan
- Department of Anesthesiology and Pain Medicine, University of Kansas Health System, Kansas City, KS 66160, USA
| | - Miles Sanderson
- Department of Anesthesiology and Pain Medicine, University of Kansas Health System, Kansas City, KS 66160, USA
| | - Dan T. Vu
- Department of Anesthesiology and Pain Medicine, University of Kansas Health System, Kansas City, KS 66160, USA
| | - Gabriella Smith
- School of Medicine, University of Kansas, Kansas City, KS 66160, USA
| | - Dawood Sayed
- Department of Anesthesiology and Pain Medicine, University of Kansas Health System, Kansas City, KS 66160, USA
| | - Talal Khan
- Department of Anesthesiology and Pain Medicine, University of Kansas Health System, Kansas City, KS 66160, USA
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4
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Niederhoffer T, Vanhoestenberghe A, Lancashire HT. Methods of poly(3,4)-ethylenedioxithiophene (PEDOT) electrodeposition on metal electrodes for neural stimulation and recording. J Neural Eng 2023; 20. [PMID: 36603213 DOI: 10.1088/1741-2552/acb084] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 01/05/2023] [Indexed: 01/06/2023]
Abstract
Conductive polymers are of great interest in the field of neural electrodes because of their potential to improve the interfacial properties of electrodes. In particular, the conductive polymer poly (3,4)-ethylenedioxithiophene (PEDOT) has been widely studied for neural applications.Objective:This review compares methods for electrodeposition of PEDOT on metal neural electrodes, and analyses the effects of deposition methods on morphology and electrochemical performance.Approach:Electrochemical performances were analysed against several deposition method choices, including deposition charge density and co-ion, and correlations were explained to morphological and structural arguments as well as characterisation methods choices.Main results:Coating thickness and charge storage capacity are positively correlated with PEDOT electrodeposition charge density. We also show that PEDOT coated electrode impedance at 1 kHz, the only consistently reported impedance quantity, is strongly dependent upon electrode radius across a wide range of studies, because PEDOT coatings reduces the reactance of the complex impedance, conferring a more resistive behaviour to electrodes (at 1 kHz) dominated by the solution resistance and electrode geometry. This review also summarises how PEDOT co-ion choice affects coating structure and morphology and shows that co-ions notably influence the charge injection limit but have a limited influence on charge storage capacity and impedance. Finally we discuss the possible influence of characterisation methods to assess the robustness of comparisons between published results using different methods of characterisation.Significance:This review aims to serve as a common basis for researchers working with PEDOT by showing the effects of deposition methods on electrochemical performance, and aims to set a standard for accurate and uniform reporting of methods.
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Affiliation(s)
- Thomas Niederhoffer
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, United Kingdom
| | - Anne Vanhoestenberghe
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Henry T Lancashire
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, United Kingdom
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5
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Recent progress in multifunctional conjugated polymer nanomaterial-based synergistic combination phototherapy for microbial infection theranostics. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2022.214701] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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6
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Taylor G, Paladines R, Marti A, Jacobs D, Tint S, Fones A, Hamilton H, Yu L, Amini S, Hettinger J. Electrochemical enhancement of reactively sputtered rhodium, ruthenium, and iridium oxide thin films for neural modulation, sensing, and recording applications. Electrochim Acta 2021. [DOI: 10.1016/j.electacta.2021.139118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Gori M, Vadalà G, Giannitelli SM, Denaro V, Di Pino G. Biomedical and Tissue Engineering Strategies to Control Foreign Body Reaction to Invasive Neural Electrodes. Front Bioeng Biotechnol 2021; 9:659033. [PMID: 34113605 PMCID: PMC8185207 DOI: 10.3389/fbioe.2021.659033] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 04/27/2021] [Indexed: 12/21/2022] Open
Abstract
Neural-interfaced prostheses aim to restore sensorimotor limb functions in amputees. They rely on bidirectional neural interfaces, which represent the communication bridge between nervous system and neuroprosthetic device by controlling its movements and evoking sensory feedback. Compared to extraneural electrodes (i.e., epineural and perineural implants), intraneural electrodes, implanted within peripheral nerves, have higher selectivity and specificity of neural signal recording and nerve stimulation. However, being implanted in the nerve, their main limitation is represented by the significant inflammatory response that the body mounts around the probe, known as Foreign Body Reaction (FBR), which may hinder their rapid clinical translation. Furthermore, the mechanical mismatch between the consistency of the device and the surrounding neural tissue may contribute to exacerbate the inflammatory state. The FBR is a non-specific reaction of the host immune system to a foreign material. It is characterized by an early inflammatory phase eventually leading to the formation of a fibrotic capsule around intraneural interfaces, which increases the electrical impedance over time and reduces the chronic interface biocompatibility and functionality. Thus, the future in the reduction and control of the FBR relies on innovative biomedical strategies for the fabrication of next-generation neural interfaces, such as the development of more suitable designs of the device with smaller size, appropriate stiffness and novel conductive and biomimetic coatings for improving their long-term stability and performance. Here, we present and critically discuss the latest biomedical approaches from material chemistry and tissue engineering for controlling and mitigating the FBR in chronic neural implants.
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Affiliation(s)
- Manuele Gori
- Laboratory for Regenerative Orthopaedics, Department of Orthopaedic Surgery and Traumatology, Università Campus Bio-Medico di Roma, Rome, Italy
- Institute of Biochemistry and Cell Biology (IBBC) - National Research Council (CNR), Rome, Italy
| | - Gianluca Vadalà
- Laboratory for Regenerative Orthopaedics, Department of Orthopaedic Surgery and Traumatology, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Sara Maria Giannitelli
- Laboratory of Tissue Engineering, Department of Engineering, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Vincenzo Denaro
- Laboratory for Regenerative Orthopaedics, Department of Orthopaedic Surgery and Traumatology, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Giovanni Di Pino
- NeXT: Neurophysiology and Neuroengineering of Human-Technology Interaction Research Unit, Università Campus Bio-Medico di Roma, Rome, Italy
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8
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Hejazi M, Tong W, Ibbotson MR, Prawer S, Garrett DJ. Advances in Carbon-Based Microfiber Electrodes for Neural Interfacing. Front Neurosci 2021; 15:658703. [PMID: 33912007 PMCID: PMC8072048 DOI: 10.3389/fnins.2021.658703] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 03/22/2021] [Indexed: 12/20/2022] Open
Abstract
Neural interfacing devices using penetrating microelectrode arrays have emerged as an important tool in both neuroscience research and medical applications. These implantable microelectrode arrays enable communication between man-made devices and the nervous system by detecting and/or evoking neuronal activities. Recent years have seen rapid development of electrodes fabricated using flexible, ultrathin carbon-based microfibers. Compared to electrodes fabricated using rigid materials and larger cross-sections, these microfiber electrodes have been shown to reduce foreign body responses after implantation, with improved signal-to-noise ratio for neural recording and enhanced resolution for neural stimulation. Here, we review recent progress of carbon-based microfiber electrodes in terms of material composition and fabrication technology. The remaining challenges and future directions for development of these arrays will also be discussed. Overall, these microfiber electrodes are expected to improve the longevity and reliability of neural interfacing devices.
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Affiliation(s)
- Maryam Hejazi
- School of Physics, The University of Melbourne, Parkville, VIC, Australia
| | - Wei Tong
- School of Physics, The University of Melbourne, Parkville, VIC, Australia
- National Vision Research Institute, The Australian College of Optometry, Carlton, VIC, Australia
| | - Michael R. Ibbotson
- National Vision Research Institute, The Australian College of Optometry, Carlton, VIC, Australia
- Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, VIC, Australia
| | - Steven Prawer
- School of Physics, The University of Melbourne, Parkville, VIC, Australia
| | - David J. Garrett
- School of Physics, The University of Melbourne, Parkville, VIC, Australia
- School of Engineering, RMIT University, Melbourne, VIC, Australia
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9
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Saunier V, Flahaut E, Blatché MC, Bergaud C, Maziz A. Carbon nanofiber-PEDOT composite films as novel microelectrode for neural interfaces and biosensing. Biosens Bioelectron 2020; 165:112413. [PMID: 32729532 DOI: 10.1016/j.bios.2020.112413] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 06/24/2020] [Accepted: 06/25/2020] [Indexed: 12/17/2022]
Abstract
A clear need exists for novel nanostructured materials that are capable to meet the performance criteria of a number of neuronal therapies including neural recording, stimulation and sensing of bioactive molecules at the electrode-tissue interface. By combining Poly (3,4-ethylenedioxythiophene) (PEDOT), with Carbon Nanofibers (CNFs), we demonstrate a versatile approach for the synthesis of a novel composite material PEDOT:CNF with remarkable electrochemical properties, combining low impedance, high surface area, high charge injection capability and reliable neurotransmitters monitoring using amperometric techniques. The oxidized CNFs were utilized as dopants of PEDOT to prepare the composite coatings through electrochemical deposition on neural microelectrodes arrays (MEA). The PEDOT:CNF modified microelectrodes demonstrated the low specific impedance of 1.28 MΩ μm2 at 1 kHz and results in unrivalled charge injection limit of 10.03 mC/cm2 when compared to other reported organic electrode nanomaterials. Furthermore, amperometric detection performances were determined for the neurotransmitters dopamine and serotonin, exhibiting linear concentration range from 0.1 to 9 μM and from 0.06 to 9 μM respectively, high sensitivities (44.54 pA/nM.μm2 and 71.08 pA/nM.μm2, respectively) and low detection limits (0.045 μM and 0.056 μM, respectively). Cell viability was investigated on PEDOT:CNF coated microelectrodes to show that the composite material does not advocate any cytotoxicity. Taken together, these results suggest the great potential of PEDOT:CNF composite for developing next-generation multifunctional microelectrodes for applications in neural therapies.
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Affiliation(s)
- Valentin Saunier
- LAAS-CNRS, Université de Toulouse, CNRS, F-31031 Toulouse, France
| | - Emmanuel Flahaut
- CIRIMAT, Université de Toulouse, CNRS, 118 route de Narbonne, F-31062, Toulouse, France
| | | | | | - Ali Maziz
- LAAS-CNRS, Université de Toulouse, CNRS, F-31031 Toulouse, France.
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10
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Zeng Q, Zhang Y, Wu T. High-performance Nanocrystal Platinum on Hierarchical Microelectrode for Biochemical Sensing. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2019:1062-1065. [PMID: 31946077 DOI: 10.1109/embc.2019.8857173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A high-performance hierarchical microelectrode array was reported, which significantly enlarged the surface area and reduced edge effect of the unevenly distributed electric field, using novel nanocrystal platinum (Pt) surface modification and hierarchical topologies. A hierarchical three-dimensional (3D) nanostructured Pt was introduced on the surface of microelectrodes (diameter Φ=10 pm, and seed pad Φ=200 μm) to reduce the impedance by ~91.2% down to 2.63 kn at 1kHz, and increase the cathodic charge storage capacity (CSCc) by ~60 times up to 217.9 mC.cm-2 compared with that of bare Pt substrate, demonstrating superior electrochemical performances to the traditional modified electrodes. In addition, the hierarchical microelectrodes exhibited great stability and linearity for glucose sensing with a detection limit of ~1.5 μM, which showed potential applications for neural interface and biochemical sensing.
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11
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Sung C, Jeon W, Nam KS, Kim Y, Butt H, Park S. Multimaterial and multifunctional neural interfaces: from surface-type and implantable electrodes to fiber-based devices. J Mater Chem B 2020; 8:6624-6666. [DOI: 10.1039/d0tb00872a] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Development of neural interfaces from surface electrodes to fibers with various type, functionality, and materials.
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Affiliation(s)
- Changhoon Sung
- Department of Bio and Brain Engineering
- Korea Advanced Institute of Science and Technology (KAIST)
- Daejeon 34141
- Republic of Korea
| | - Woojin Jeon
- Department of Bio and Brain Engineering
- Korea Advanced Institute of Science and Technology (KAIST)
- Daejeon 34141
- Republic of Korea
| | - Kum Seok Nam
- School of Electrical Engineering
- Korea Advanced Institute of Science and Technology (KAIST)
- Daejeon 34141
- Republic of Korea
| | - Yeji Kim
- Department of Bio and Brain Engineering
- Korea Advanced Institute of Science and Technology (KAIST)
- Daejeon 34141
- Republic of Korea
| | - Haider Butt
- Department of Mechanical Engineering
- Khalifa University
- Abu Dhabi 127788
- United Arab Emirates
| | - Seongjun Park
- Department of Bio and Brain Engineering
- Korea Advanced Institute of Science and Technology (KAIST)
- Daejeon 34141
- Republic of Korea
- KAIST Institute for Health Science and Technology (KIHST)
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12
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Zeng Q, Zhang Y, Wu T, Sun B, Xia K, Mark Humayun S. 3D Nano-crystal Platinum for High-performance Neural Electrode. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2019; 2018:4217-4220. [PMID: 30441284 DOI: 10.1109/embc.2018.8513278] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A novel three-dimensional (3D) nano-crystal platinum (Pt) was introduced as a high-performance layer on the Pt substrate to provide extremely large surface, which significantly reduced electrical impedance by ˜ and increased the cathodic charge storage capacity (CSCc) up to ˜100 mC\textbullet(27 times) compared with that of bare Pt electrodes. In addition, the 3D nano-crystal Pt coating exhibited great mechanical and electrochemical stability as well as biocompatibility, which was critical and beneficial for effective neural stimulation/recording electrodes for practical applications.
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Rossetti N, Luthra P, Hagler J, Jae Lee AH, Bodart C, Li X, Ducharme G, Soavi F, Amilhon B, Cicoira F. Poly(3,4-ethylenedioxythiophene) (PEDOT) Coatings for High-Quality Electromyography Recording. ACS APPLIED BIO MATERIALS 2019; 2:5154-5163. [DOI: 10.1021/acsabm.9b00809] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Nicolò Rossetti
- Department of Chemical Engineering, Polytechnique Montréal, Montréal, Québec H3T 1J4, Canada
| | - Prabhjot Luthra
- Department of Chemical Engineering, Polytechnique Montréal, Montréal, Québec H3T 1J4, Canada
| | - Jo’Elen Hagler
- Department of Chemical Engineering, Polytechnique Montréal, Montréal, Québec H3T 1J4, Canada
| | - Ada Hyun Jae Lee
- Department of Chemical Engineering, Polytechnique Montréal, Montréal, Québec H3T 1J4, Canada
| | - Côme Bodart
- Department of Chemical Engineering, Polytechnique Montréal, Montréal, Québec H3T 1J4, Canada
| | - Xinda Li
- Department of Chemical Engineering, Polytechnique Montréal, Montréal, Québec H3T 1J4, Canada
| | | | - Francesca Soavi
- Dipartimento di Chimica Giacomo Ciamician, Alma Mater Studiorum Università di Bologna, Via Selmi 2, Bologna 40126, Italy
| | - Bénédicte Amilhon
- CHU Sainte-Justine Research Center, Montréal H3T 1C5, Canada
- Department of Neurosciences, Université de Montréal, Montréal H3C 3J7, Canada
| | - Fabio Cicoira
- Department of Chemical Engineering, Polytechnique Montréal, Montréal, Québec H3T 1J4, Canada
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14
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Reddy S, Xiao Q, Liu H, Li C, Chen S, Wang C, Chiu K, Chen N, Tu Y, Ramakrishna S, He L. Bionanotube/Poly(3,4-ethylenedioxythiophene) Nanohybrid as an Electrode for the Neural Interface and Dopamine Sensor. ACS APPLIED MATERIALS & INTERFACES 2019; 11:18254-18267. [PMID: 31034196 DOI: 10.1021/acsami.9b04862] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Poly(3,4-ethylene dioxythiophene) (PEDOT) is a promising conductive material widely used for interfacing with tissues in biomedical fields because of its unique properties. However, obtaining high charge injection capability and high stability remains challenging. In this study, pristine carbon nanotubes (CNTs) modified by dopamine (DA) self-polymerization on the surface polydopamine (PDA@CNTs) were utilized as dopants of PEDOT to prepare hybrid films through electrochemical deposition on the indium tin oxide (ITO) electrode. The PDA@CNTs-PEDOT film of the nanotube network topography exhibited excellent stability and strong adhesion to the ITO substrate compared with PEDOT and PEDOT/ p-toulene sulfonate. The PDA@CNTs-PEDOT-coated ITO electrodes demonstrated lower impedance and enhanced charge storage capacity than the bare ITO. When applying exogenous electrical stimulation (ES), robust long neurites sprouted from the dorsal root ganglion (DRG) neurons cultured on the PDA@CNTs-PEDOT film. Moreover, ES promoted Schwann cell migration out from the DRG spheres and enhanced myelination. The PDA@CNTs-PEDOT film served as an excellent electrochemical sensor for the detection of DA in the presence of biomolecule interferences. Results would shed light into the advancement of conducting nanohybrids for applications in the multifunctional bioelectrode in neuroscience.
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Affiliation(s)
- Sathish Reddy
- Guangdong-Hongkong-Macau Institute of CNS Regeneration (GHMICR), MOE Joint International Research Laboratory of CNS Regeneration , Jinan University , Guangzhou , Guangdong , 510632 , China
| | - Qiao Xiao
- College of Life Science and Technology , Jinan University , Guangzhou , Guangdong , 510632 , China
| | - Haiqian Liu
- Guangdong-Hongkong-Macau Institute of CNS Regeneration (GHMICR), MOE Joint International Research Laboratory of CNS Regeneration , Jinan University , Guangzhou , Guangdong , 510632 , China
| | - Chuping Li
- Guangdong-Hongkong-Macau Institute of CNS Regeneration (GHMICR), MOE Joint International Research Laboratory of CNS Regeneration , Jinan University , Guangzhou , Guangdong , 510632 , China
| | - Shengfeng Chen
- Guangdong-Hongkong-Macau Institute of CNS Regeneration (GHMICR), MOE Joint International Research Laboratory of CNS Regeneration , Jinan University , Guangzhou , Guangdong , 510632 , China
| | - Cong Wang
- Department of Traditional Therapy , The Second Clinical College of Guangzhou University of Chinese Medicine , Guangzhou 510120 , China
| | - Kin Chiu
- State Key Laboratory of Brain and Cognitive Sciences , The University of Hong Kong , Hong Kong SAR , P. R. China
| | - Nuan Chen
- Center for Nanofibers and Nanotechnology, Department of Mechanical Engineering, Faculty of Engineering , National University of Singapore , 117576 , Singapore
| | - Yujie Tu
- College of Life Science and Technology , Jinan University , Guangzhou , Guangdong , 510632 , China
| | - Seeram Ramakrishna
- Guangdong-Hongkong-Macau Institute of CNS Regeneration (GHMICR), MOE Joint International Research Laboratory of CNS Regeneration , Jinan University , Guangzhou , Guangdong , 510632 , China
- Center for Nanofibers and Nanotechnology, Department of Mechanical Engineering, Faculty of Engineering , National University of Singapore , 117576 , Singapore
| | - Liumin He
- Guangdong-Hongkong-Macau Institute of CNS Regeneration (GHMICR), MOE Joint International Research Laboratory of CNS Regeneration , Jinan University , Guangzhou , Guangdong , 510632 , China
- College of Life Science and Technology , Jinan University , Guangzhou , Guangdong , 510632 , China
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15
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Bodart C, Rossetti N, Hagler J, Chevreau P, Chhin D, Soavi F, Schougaard SB, Amzica F, Cicoira F. Electropolymerized Poly(3,4-ethylenedioxythiophene) (PEDOT) Coatings for Implantable Deep-Brain-Stimulating Microelectrodes. ACS APPLIED MATERIALS & INTERFACES 2019; 11:17226-17233. [PMID: 30978001 DOI: 10.1021/acsami.9b03088] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Conducting polymers have been widely explored as coating materials for metal electrodes to improve neural signal recording and stimulation because of their mixed electronic-ionic conduction and biocompatibility. In particular, the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) is one of the best candidates for biomedical applications due to its high conductivity and good electrochemical stability. Coating metal electrodes with PEDOT has shown to enhance the electrode's performance by decreasing the impedance and increasing the charge storage capacity. However, PEDOT-coated metal electrodes often have issues with delamination and stability, resulting in decreased device performance and lifetime. In this work, we were able to electropolymerize PEDOT coatings on sharp platinum-iridium recording and stimulating neural electrodes and demonstrated its mechanical and electrochemical stability. Electropolymerization of PEDOT:tetrafluoroborate was carried out in three different solvents: propylene carbonate, acetonitrile, and water. The stability of the coatings was assessed via ultrasonication, phosphate buffer solution soaking test, autoclave sterilization, and electrical pulsing. Coatings prepared with propylene carbonate or acetonitrile possessed excellent electrochemical stability and survived autoclave sterilization, prolonged soaking, and electrical stimulation without major changes in electrochemical properties. Stimulating microelectrodes were implanted in rats and stimulated daily, for 7 and 15 days. The electrochemical properties monitored in vivo demonstrated that the stimulation procedure for both coated and uncoated electrodes decreased the impedance.
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Affiliation(s)
- Côme Bodart
- Department of Chemical Engineering , Polytechnique Montréal , Montréal , Québec H3C 3J7 , Canada
| | - Nicolò Rossetti
- Department of Chemical Engineering , Polytechnique Montréal , Montréal , Québec H3C 3J7 , Canada
| | - Jo'Elen Hagler
- Department of Chemical Engineering , Polytechnique Montréal , Montréal , Québec H3C 3J7 , Canada
| | - Pauline Chevreau
- Department of Chemical Engineering , Polytechnique Montréal , Montréal , Québec H3C 3J7 , Canada
| | - Danny Chhin
- Department of Chemistry , Université du Québec à Montréal , Montréal , Québec H3T 1J4 , Canada
| | - Francesca Soavi
- Dipartimento di Chimica Giacomo Ciamician , Alma Mater Studiorum Università di Bologna , Via Selmi 2 , Bologna 40126 , Italy
| | - Steen Brian Schougaard
- Department of Chemistry , Université du Québec à Montréal , Montréal , Québec H3T 1J4 , Canada
| | - Florin Amzica
- School of Medicine/Dentistry , Université de Montréal , Montréal , Québec H3C 3J7 , Canada
| | - Fabio Cicoira
- Department of Chemical Engineering , Polytechnique Montréal , Montréal , Québec H3C 3J7 , Canada
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16
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Enhanced spinal cord microstimulation using conducting polymer-coated carbon microfibers. Acta Biomater 2019; 90:71-86. [PMID: 30904548 DOI: 10.1016/j.actbio.2019.03.037] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 03/18/2019] [Accepted: 03/19/2019] [Indexed: 12/30/2022]
Abstract
Intraspinal microstimulation (ISMS) may help to restore motor functions after spinal cord injury. ISMS caudal to the lesion activates motoneurons and evokes selective movements with graded force in rats and other mammals. We investigated the safety and effectiveness of conducting polymer (CP)-coated carbon microfibers (CMFs) for ISMS. 7-µm-diameter CMFs coated with poly(3,4-ethylenedioxythiophene) doped with poly[(4-styrenesulfonic acid)-co-(maleic acid)] (PEDOT:PSS-co-MA) were used to apply current-controlled biphasic electric pulses at the cervical spinal cord (C7) of anesthetized rats. Electrode performance and motoneuron activation, as readout by voltage transients, cyclic voltammetry, electrochemical impedance spectroscopy, electromyography (EMG) and foreleg kinematics, were investigated as a function of microfiber length (50 µm vs. 250 µm) and presence of polymer coating. The microfibers were very effective in activating specific spinal motoneurons, with the lowest stimulus thresholds varying between -28 µA and -46 µA in the cathodic phase. EMG and kinematic thresholds decreased when the microfiber tip approached the targeted motor nucleus (triceps brachii, t.b.) from the dorsal spinal cord surface. ISMS with polymer-coated CMFs produced higher electrical activity in the t.b. fascicles compared to bare CMFs. PEDOT:PSS-co-MA coating of 250-µm CMFs avoided the generation of unsafe overvoltages for biphasic pulses up to -80/+40 µA in vivo, although the positive effect of the conducting polymer was lost after the application of a few thousands of electric pulses. Thus, CP-coated CMFs may provide an effective and minimally invasive electrode for ISMS; however, polymer optimization is still required to improve its electrical stability and safety for long-term use. Statement of significance Intraspinal microstimulation may restore motor functions after spinal cord injury. In the present study we demonstrate that carbon microfibers (CMFs) coated with the conducting polymer PEDOT:PSS-co-MA can be advantageously used for this purpose. These microfibers allow for both effective and temporarily safe electrical activation of spinal motor circuits with high spatial resolution. The presence of the polymer enhances the effectiveness of the electrical stimuli to recruit spinal motoneurons. Thus, conducting polymer-coated CMFs have potential for the development of advanced neuroprosthetic devices, although further improvements are needed regarding their electrochemical and mechanical stability.
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17
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Humayun MS. High-performance iridium oxide/platinum nano-leaf composite coatings on microelectrodes for neural stimulation/recording. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2018; 2017:1070-1073. [PMID: 29060059 DOI: 10.1109/embc.2017.8037012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A novel platinum (Pt) nano-leaf interfacial layer between the Pt substrate and iridium oxide (IrOx) coating, significantly reduced impedance and increased cathodic charge storage capacity (CSCc) for neural microelectrodes. Combining the advantages of both materials, herein a lower impedance and higher CSCc of IrOx/Pt nano-leaf composite coatings than each simple coating was fabricated with nanoscale roughness. Furthermore, it demonstrated excellent mechanical and electrochemical stability, which was beneficial for effective neural stimulation/recording in various applications.
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18
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Shoffstall AJ, Capadona JR. Bioinspired materials and systems for neural interfacing. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2018. [DOI: 10.1016/j.cobme.2018.05.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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19
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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] [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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20
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Electrodeposited Iridium Oxide on Platinum Nanocones for Improving Neural Stimulation Microelectrodes. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.03.213] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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21
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Löffler S, Seyock S, Nybom R, Jacobson GB, Richter-Dahlfors A. Electrochemically triggered release of acetylcholine from scCO 2 impregnated conductive polymer films evokes intracellular Ca 2+ signaling in neurotypic SH-SY5Y cells. J Control Release 2016; 243:283-290. [PMID: 27793684 DOI: 10.1016/j.jconrel.2016.10.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 10/10/2016] [Accepted: 10/23/2016] [Indexed: 12/27/2022]
Abstract
Implantable devices for electronically triggered drug release are attractive to achieve spatial and temporal control over drug concentrations in patients. Realization of such devices is, however, associated with technical and biological challenges. Among these are containment of drug reservoirs, lack of precise control cues, as well as the charge and size of the drug. Here, we present a method for electronically triggered release of the quaternary ammonium cation acetylcholine (ACh) from an impregnated conductive polymer film. Using supercritical carbon dioxide (scCO2), a film of PEDOT/PSS (poly(3,4)-ethylenedioxythiophene doped with poly(styrenesulfonate)) is impregnated with the neurotransmitter acetylcholine. The gentle scCO2 process generated a dry, drug-impregnated surface, well suited for interaction with biological material, while maintaining normal electrochemical properties of the polymer. Electrochemical switching of impregnated PEDOT/PSS films stimulated release of ACh from the polymer matrix, likely due to swelling mediated by the influx and efflux of charged and solvated ions. Triggered release of ACh did not affect the biological activity of the drug. This was shown by real-time monitoring of intracellular Ca2+ signaling in neurotypic cells growing on the impregnated polymer surface. Collectively, scCO2 impregnation of conducting polymers offers the first one-step, dopant-independent drug impregnation process, potentially facilitating loading of both anionic and cationic drugs that can be dissolved in scCO2 on its own or by using a co-solvent. We foresee that scCO2-loaded devices for electronically triggered drug release will create novel opportunities when generating active bio-coatings, tunable for specific needs, in a variety of medical settings.
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Affiliation(s)
- Susanne Löffler
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Silke Seyock
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Rolf Nybom
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Gunilla B Jacobson
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Agneta Richter-Dahlfors
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
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22
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Meijs S, Alcaide M, Sørensen C, McDonald M, Sørensen S, Rechendorff K, Gerhardt A, Nesladek M, Rijkhoff NJM, Pennisi CP. Biofouling resistance of boron-doped diamond neural stimulation electrodes is superior to titanium nitride electrodesin vivo. J Neural Eng 2016; 13:056011. [DOI: 10.1088/1741-2560/13/5/056011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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23
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Charkhkar H, Knaack GL, McHail DG, Mandal HS, Peixoto N, Rubinson JF, Dumas TC, Pancrazio JJ. Chronic intracortical neural recordings using microelectrode arrays coated with PEDOT-TFB. Acta Biomater 2016; 32:57-67. [PMID: 26689462 DOI: 10.1016/j.actbio.2015.12.022] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 11/22/2015] [Accepted: 12/11/2015] [Indexed: 11/27/2022]
Abstract
Microelectrode arrays have been extensively utilized to record extracellular neuronal activity for brain-machine interface applications. Modifying the microelectrodes with conductive polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) has been reported to be advantageous because it increases the effective surface area of the microelectrodes, thereby decreasing impedance and enhancing charge transfer capacity. However, the long term stability and integrity of such coatings for chronic recordings remains unclear. Previously, our group has demonstrated that use of the smaller counter ion tetrafluoroborate (TFB) during electrodeposition increased the stability of the PEDOT coatings in vitro compared to the commonly used counter ion poly(styrenesulfonate) (PSS). In the current work, we examined the long-term in vivo performance of PEDOT-TFB coated microelectrodes. To do so, we selectively modified half of the microelectrodes on NeuroNexus single shank probes with PEDOT-TFB while the other half of the microelectrodes were modified with gold as a control. The modified probes were then implanted into the primary motor cortex of rats. Single unit recordings were observed on both PEDOT-TFB and gold control microelectrodes for more than 12 weeks. Compared to the gold-coated microelectrodes, the PEDOT-TFB coated microelectrodes exhibited an overall significantly lower impedance and higher number of units per microelectrode specifically for the first four weeks. The majority of PEDOT-TFB microelectrodes with activity had an impedance magnitude lower than 400 kΩ at 1 kHz. Our equivalent circuit modeling of the impedance data suggests stability in the polymer-related parameters for the duration of the study. In addition, when comparing PEDOT-TFB microelectrodes with and without long-term activity, we observed a distinction in certain circuit parameters for these microelectrodes derived from equivalent circuit modeling prior to implantation. This observation may prove useful in qualifying PEDOT-TFB microelectrodes with a greater likelihood of registering long-term activity. Overall, our findings confirm that PEDOT-TFB is a chronically stable coating for microelectrodes to enable neural recording. STATEMENT OF SIGNIFICANCE Microelectrode arrays have been extensively utilized to record extracellular neuronal activity for brain-machine interface applications. Poly(3,4-ethylenedioxythiophene) (PEDOT) has gained interest because of its unique electrochemical characteristics and its excellent intrinsic electrical conductivity. However, the long-term stability of the PEDOT film, especially for chronic neural applications, is unclear. In this manuscript, we report for the first time the use of highly stable PEDOT doped with tetrafluoroborate (TFB) for long-term neural recordings. We show that PEDOT-TFB coated microelectrodes on average register more units compared to control gold microelectrodes for at least first four weeks post implantation. We collected the in vivo impedance data over a wide frequency spectrum and developed an equivalent circuit model which helped us determine certain parameters to distinguish between PEDOT-TFB microelectrodes with and without long-term activity. Our findings suggest that PEDOT-TFB is a chronically stable coating for neural recording microelectrodes. As such, PEDOT-TFB could facilitate chronic recordings with ultra-small and high-density neural arrays.
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24
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Alba NA, Du ZJ, Catt KA, Kozai TDY, Cui XT. In Vivo Electrochemical Analysis of a PEDOT/MWCNT Neural Electrode Coating. BIOSENSORS-BASEL 2015; 5:618-46. [PMID: 26473938 PMCID: PMC4697137 DOI: 10.3390/bios5040618] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 09/23/2015] [Accepted: 09/30/2015] [Indexed: 12/25/2022]
Abstract
Neural electrodes hold tremendous potential for improving understanding of brain function and restoring lost neurological functions. Multi-walled carbon nanotube (MWCNT) and dexamethasone (Dex)-doped poly(3,4-ethylenedioxythiophene) (PEDOT) coatings have shown promise to improve chronic neural electrode performance. Here, we employ electrochemical techniques to characterize the coating in vivo. Coated and uncoated electrode arrays were implanted into rat visual cortex and subjected to daily cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) for 11 days. Coated electrodes experienced a significant decrease in 1 kHz impedance within the first two days of implantation followed by an increase between days 4 and 7. Equivalent circuit analysis showed that the impedance increase is the result of surface capacitance reduction, likely due to protein and cellular processes encapsulating the porous coating. Coating's charge storage capacity remained consistently higher than uncoated electrodes, demonstrating its in vivo electrochemical stability. To decouple the PEDOT/MWCNT material property changes from the tissue response, in vitro characterization was conducted by soaking the coated electrodes in PBS for 11 days. Some coated electrodes exhibited steady impedance while others exhibiting large increases associated with large decreases in charge storage capacity suggesting delamination in PBS. This was not observed in vivo, as scanning electron microscopy of explants verified the integrity of the coating with no sign of delamination or cracking. Despite the impedance increase, coated electrodes successfully recorded neural activity throughout the implantation period.
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Affiliation(s)
- Nicolas A Alba
- Department of Bioengineering, University of Pittsburgh, 5056 Biomedical Science Tower 3, 3501 Fifth Avenue, Pittsburgh, PA 15213, USA.
- Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA 15260, USA.
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15260, USA.
| | - Zhanhong J Du
- Department of Bioengineering, University of Pittsburgh, 5056 Biomedical Science Tower 3, 3501 Fifth Avenue, Pittsburgh, PA 15213, USA.
- Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA 15260, USA.
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15260, USA.
| | - Kasey A Catt
- Department of Bioengineering, University of Pittsburgh, 5056 Biomedical Science Tower 3, 3501 Fifth Avenue, Pittsburgh, PA 15213, USA.
| | - Takashi D Y Kozai
- Department of Bioengineering, University of Pittsburgh, 5056 Biomedical Science Tower 3, 3501 Fifth Avenue, Pittsburgh, PA 15213, USA.
- Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA 15260, USA.
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15260, USA.
- NeuroTech Center of the University of Pittsburgh Brain Institute, Pittsburgh, PA 15260, USA.
| | - X Tracy Cui
- Department of Bioengineering, University of Pittsburgh, 5056 Biomedical Science Tower 3, 3501 Fifth Avenue, Pittsburgh, PA 15213, USA.
- Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA 15260, USA.
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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25
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Mandal HS, Cliff RO, Pancrazio JJ. Freeze Drying Improves the Shelf-Life of Conductive Polymer Modified Neural Electrodes. Bioengineering (Basel) 2015; 2:176-183. [PMID: 28952476 PMCID: PMC5597183 DOI: 10.3390/bioengineering2030176] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 08/04/2015] [Indexed: 11/16/2022] Open
Abstract
Coating microelectrodes with conductive polymer is widely recognized to decrease impedance and improve performance of implantable neural devices during recording and stimulation. A concern for wide-spread use of this approach is shelf-life, i.e., the electrochemical stability of the coated microelectrodes prior to use. In this work, we investigated the possibility of using the freeze-drying process in order to retain the native low impedance state and, thereby, improve the shelf-life of conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT)-PSS modified neural electrodes. Control PEDOT-PSS coated microelectrodes demonstrated a significant increase in impedance at 1 kHz after 41-50 days of room temperature storage. Based on equivalent circuit modeling derived from electrochemical impedance spectroscopy, this increase in impedance could be largely attributed to a decrease in the interfacial capacitance consistent with a collapse and closing of the porous structure of the polymeric coating. Time-dependent electrochemical impedance measurements revealed higher stability of the freeze-dried coated microelectrodes compared to the controls, such that impedance values after 41-50 days appeared to be indistinguishable from the initial levels. This suggests that freeze drying PEDOT-PSS coated microelectrodes correlates with enhanced electrochemical stability during shelf storage.
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Affiliation(s)
- Himadri S Mandal
- Blackrock Microsystems, 630 Komas Dr #200, Salt Lake City, UT 84108, USA.
| | - Richard O Cliff
- System of Systems Analytics, 11250 Waples Mill Road, Fairfax, VA 22030, USA.
| | - Joseph J Pancrazio
- Department of Bioengineering, Volgenau School of Engineering, George Mason University, 4400 University Drive, MS 1G5, Fairfax, VA 22030, USA.
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