1
|
He Q, Yang Y, Ge P, Li S, Chai X, Luo Z, Zhao J. The brain nebula: minimally invasive brain-computer interface by endovascular neural recording and stimulation. J Neurointerv Surg 2024:jnis-2023-021296. [PMID: 38388478 DOI: 10.1136/jnis-2023-021296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 01/19/2024] [Indexed: 02/24/2024]
Abstract
A brain-computer interface (BCI) serves as a direct communication channel between brain activity and external devices, typically a computer or robotic limb. Advances in technology have led to the increasing use of intracranial electrical recording or stimulation in the treatment of conditions such as epilepsy, depression, and movement disorders. This indicates that BCIs can offer clinical neurological rehabilitation for patients with disabilities and functional impairments. They also provide a means to restore consciousness and functionality for patients with sequelae from major brain diseases. Whether invasive or non-invasive, the collected cortical or deep signals can be decoded and translated for communication. This review aims to provide an overview of the advantages of endovascular BCIs compared with conventional BCIs, along with insights into the specific anatomical regions under study. Given the rapid progress, we also provide updates on ongoing clinical trials and the prospects for current research involving endovascular electrodes.
Collapse
Affiliation(s)
- Qiheng He
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
- Brain Computer Interface Transitional Research Center, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Yi Yang
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
- Brain Computer Interface Transitional Research Center, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
- China National Center for Neurological Disorders, Beijing, China
- China National Clinical Research Center for Neurological Diseases, Beijing, China
- National Research Center for Rehabilitation Technical Aids, Beijing, China
- Chinese Institute for Brain Research, Beijing, People's Republic of China
- Beijing Institute of Brain Disorders, Beijing, People's Republic of China
| | - Peicong Ge
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Sining Li
- Tianjin Key Laboratory of Brain Science and Intelligent Rehabilitation, College of Artificial Intelligence, Nankai University, Tianjin, China
| | - Xiaoke Chai
- Brain Computer Interface Transitional Research Center, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Zhongqiu Luo
- Department of Neurosurgery, Shenzhen Qianhai Shekou Free Trade Zone Hospital, Shenzhen, China
| | - Jizong Zhao
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
- China National Center for Neurological Disorders, Beijing, China
- China National Clinical Research Center for Neurological Diseases, Beijing, China
| |
Collapse
|
2
|
Li L, Ibayashi K, Piscopo A, Deifelt Streese C, Chen H, Greenlee JDW, Hasan DM. Intraarterial encephalography from an acutely implanted aneurysm embolization device in awake humans. J Neurosurg 2023; 138:785-792. [PMID: 35932270 DOI: 10.3171/2022.6.jns22932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 06/09/2022] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Endovascular electroencephalography (evEEG) uses the cerebrovascular system to record electrical activity from adjacent neural structures. The safety, feasibility, and efficacy of using the Woven EndoBridge Aneurysm Embolization System (WEB) for evEEG has not been investigated. METHODS Seventeen participants undergoing awake WEB endovascular treatment of unruptured cerebral aneurysms were included. After WEB deployment and before detachment, its distal deployment wire was connected to an EEG receiver, and participants performed a decision-making task for 10 minutes. WEB and scalp recordings were captured. RESULTS All patients underwent successful embolization and evEEG with no complications. Event-related potentials were detected on scalp EEG in 9/17 (53%) patients. Of these 9 patients, a task-related low-gamma (30-70 Hz) response on WEB channels was captured in 8/9 (89%) cases. In these 8 patients, the WEB was deployed in 2 middle cerebral arteries, 3 anterior communicating arteries, the terminal internal carotid artery, and 2 basilar tip aneurysms. Electrocardiogram artifact on WEB channels was present in 12/17 cases. CONCLUSIONS The WEB implanted within cerebral aneurysms of awake patients is capable of capturing task-specific brain electrical activities. Future studies are warranted to establish the efficacy of and support for evEEG as a tool for brain recording, brain stimulation, and brain-machine interface applications.
Collapse
Affiliation(s)
- Luyuan Li
- 1Department of Neurosurgery, University of Iowa, Iowa City, Iowa
| | - Kenji Ibayashi
- 2Department of Neurosurgery, Jichi Medical University, Tochigi, Japan; and
| | - Anthony Piscopo
- 1Department of Neurosurgery, University of Iowa, Iowa City, Iowa
| | | | - Haiming Chen
- 1Department of Neurosurgery, University of Iowa, Iowa City, Iowa
| | | | - David M Hasan
- 3Department of Neurosurgery, Duke University, Durham, North Carolina
| |
Collapse
|
3
|
Thielen B, Xu H, Fujii T, Rangwala SD, Jiang W, Lin M, Kammen A, Liu C, Selvan P, Song D, Mack WJ, Meng E. Making a case for endovascular approaches for neural recording and stimulation. J Neural Eng 2023; 20:10.1088/1741-2552/acb086. [PMID: 36603221 PMCID: PMC9928900 DOI: 10.1088/1741-2552/acb086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 01/05/2023] [Indexed: 01/06/2023]
Abstract
There are many electrode types for recording and stimulating neural tissue, most of which necessitate direct contact with the target tissue. These electrodes range from large, scalp electrodes which are used to non-invasively record averaged, low frequency electrical signals from large areas/volumes of the brain, to penetrating microelectrodes which are implanted directly into neural tissue and interface with one or a few neurons. With the exception of scalp electrodes (which provide very low-resolution recordings), each of these electrodes requires a highly invasive, open brain surgical procedure for implantation, which is accompanied by significant risk to the patient. To mitigate this risk, a minimally invasive endovascular approach can be used. Several types of endovascular electrodes have been developed to be delivered into the blood vessels in the brain via a standard catheterization procedure. In this review, the existing body of research on the development and application of endovascular electrodes is presented. The capabilities of each of these endovascular electrodes is compared to commonly used direct-contact electrodes to demonstrate the relative efficacy of the devices. Potential clinical applications of endovascular recording and stimulation and the advantages of endovascular versus direct-contact approaches are presented.
Collapse
Affiliation(s)
- Brianna Thielen
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
| | - Huijing Xu
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
| | - Tatsuhiro Fujii
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Shivani D. Rangwala
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Wenxuan Jiang
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
| | - Michelle Lin
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Alexandra Kammen
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Charles Liu
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA,Neurorestoration Center, University of Southern California, Los Angeles, CA, USA
| | - Pradeep Selvan
- The Lundquist Institute for Biomedical Innovation, Torrance, CA, USA
| | - Dong Song
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
| | - William J. Mack
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Ellis Meng
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
| |
Collapse
|
4
|
Geramifard N, Lawson J, Cogan SF, Black BJ. A Novel 3D Helical Microelectrode Array for In Vitro Extracellular Action Potential Recording. MICROMACHINES 2022; 13:1692. [PMID: 36296045 PMCID: PMC9611359 DOI: 10.3390/mi13101692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [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.
Collapse
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
| |
Collapse
|
5
|
Jumaa MA, Salahuddin H, Burgess R. The Future of Endovascular Therapy. Neurology 2021; 97:S185-S193. [PMID: 34785617 DOI: 10.1212/wnl.0000000000012807] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Accepted: 04/13/2021] [Indexed: 11/15/2022] Open
Abstract
PURPOSE OF THE REVIEW This article summarizes a broad range of the most recent advances and future directions in stroke diagnostics, endovascular robotics, and neuromodulation. RECENT FINDINGS In the past 5 years, the field of interventional neurology has seen major technological advances for the diagnosis and treatment of cerebrovascular diseases. Several new technologies became available to aid in complex prehospital stroke triage, stroke diagnosis, and interpretation of radiologic findings. Robotics and neuromodulation promise to expand access to established treatments and broaden neuroendovascular indications. SUMMARY Mobile applications offer a solution to simplify prehospital diagnostic and transfer decisions. Several prehospital devices are also under development to improve the accuracy of detection of large vessel occlusion (LVO). Artificial intelligence is now routinely used in early diagnosis of LVO and for detecting salvageability of the affected brain parenchyma. Technological advances have also paved the way to incorporate endovascular robotics and neuromodulation into practice. This may expand the deliverability of established treatments and facilitate the development of cutting-edge treatments for other complex neurologic diseases.
Collapse
Affiliation(s)
- Mouhammad A Jumaa
- From the Department of Neurology, ProMedica Neurosciences Institute; and Department of Neurology, University of Toledo College of Medicine, OH.
| | - Hisham Salahuddin
- From the Department of Neurology, ProMedica Neurosciences Institute; and Department of Neurology, University of Toledo College of Medicine, OH
| | - Richard Burgess
- From the Department of Neurology, ProMedica Neurosciences Institute; and Department of Neurology, University of Toledo College of Medicine, OH
| |
Collapse
|
6
|
Ambient Light Rejection Integrated Circuit for Autonomous Adaptation on a Sub-Retinal Prosthetic System. SENSORS 2021; 21:s21165638. [PMID: 34451078 PMCID: PMC8402464 DOI: 10.3390/s21165638] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 08/18/2021] [Accepted: 08/19/2021] [Indexed: 11/17/2022]
Abstract
This paper introduces an ambient light rejection (ALR) circuit for the autonomous adaptation of a subretinal implant system. The sub-retinal implants, located beneath a bipolar cell layer, are known to have a significant advantage in spatial resolution by integrating more than a thousand pixels, compared to epi-retinal implants. However, challenges remain regarding current dispersion in high-density retinal implants, and ambient light induces pixel saturation. Thus, the technical issues of ambient light associated with a conventional image processing technique, which lead to high power consumption and area occupation, are still unresolved. Thus, it is necessary to develop a novel image-processing unit to handle ambient light, considering constraints related to power and area. In this paper, we present an ALR circuit as an image-processing unit for sub-retinal implants. We first introduced an ALR algorithm to reduce the ambient light in conventional retinal implants; next, we implemented the ALR algorithm as an application-specific integrated chip (ASIC). The ALR circuit was fabricated using a standard 0.35-μm CMOS process along with an image-sensor-based stimulator, a sensor pixel, and digital blocks. As experimental results, the ALR circuit occupies an area of 190 µm2, consumes a power of 3.2 mW and shows a maximum response time of 1.6 s at a light intensity of 20,000 lux. The proposed ALR circuit also has a pixel loss rate of 0.3%. The experimental results show that the ALR circuit leads to a sensor pixel (SP) being autonomously adjusted, depending on the light intensity.
Collapse
|
7
|
Opie NL, O'Brien TJ. The potential of closed-loop endovascular neurostimulation as a viable therapeutic approach for drug-resistant epilepsy: A critical review. Artif Organs 2021; 46:337-348. [PMID: 34101849 DOI: 10.1111/aor.14007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 05/23/2021] [Accepted: 05/27/2021] [Indexed: 11/30/2022]
Abstract
Over the last few decades, biomedical implants have successfully delivered therapeutic electrical stimulation to reduce the frequency and severity of seizures in people with drug-resistant epilepsy. However, neurostimulation approaches require invasive surgery to implant stimulating electrodes, and surgical, medical, and hardware complications are not uncommon. An endovascular approach provides a potentially safer and less invasive surgical alternative. This article critically evaluates the feasibility of endovascular closed-loop neuromodulation for the treatment of epilepsy. By reviewing literature that reported the impact of direct electrical stimulation to reduce the frequency of epileptic seizures, we identified clinically validated extracranial, cortical, and deep cortical neural targets. We identified veins in close proximity to these targets and evaluated the potential of delivering an endovascular implant to these veins based on their diameter. We then compared the risks and benefits of existing technology to describe a benchmark of clinical safety and efficacy that would need to be achieved for endovascular neuromodulation to provide therapeutic benefit. For the majority of brain regions that have been clinically demonstrated to reduce seizure occurrence in response to delivered electrical stimulation, vessels of appropriate diameter for delivery of an endovascular electrode to these regions could be achieved. This includes delivery to the vagus nerve via the 13.2 ± 0.9 mm diameter internal jugular vein, the motor cortex via the 6.5 ± 1.7 mm diameter superior sagittal sinus, and the cerebellum via the 7.7 ± 1.4 mm diameter sigmoid sinus or 6.2 ± 1.4 mm diameter transverse sinus. Deep cerebral targets can also be accessed with an endovascular approach, with the 1.9 ± 0.5 mm diameter internal cerebral vein and 1.2-mm-diameter thalamostriate vein lying in close proximity to the anterior and centromedian nuclei of the thalamus, respectively. This work identified numerous veins that are in close proximity to conventional stimulation targets that are of a diameter large enough for delivery and deployment of an endovascular electrode array, supporting future work to assess clinical efficacy and chronic safety of an endovascular approach to deliver therapeutic neurostimulation.
Collapse
Affiliation(s)
- Nicholas L Opie
- Vascular Bionics Laboratory, Department of Medicine, The University of Melbourne, Parkville, VIC, Australia.,Synchron Inc., San Francisco, CA, USA
| | - Terence J O'Brien
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia.,Department of Neurology, Alfred Health, Melbourne, VIC, Australia
| |
Collapse
|
8
|
Vatsyayan R, Cleary D, Martin JR, Halgren E, Dayeh SA. Electrochemical safety limits for clinical stimulation investigated using depth and strip electrodes in the pig brain. J Neural Eng 2021; 18. [PMID: 34015769 DOI: 10.1088/1741-2552/ac038b] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 05/20/2021] [Indexed: 11/12/2022]
Abstract
Objective. Diagnostic and therapeutic electrical stimulation are increasingly utilized with the rise of neuromodulation devices. However, systematic investigations that depict the practical clinical stimulation paradigms (bipolar, two-electrode configuration) to determine the safety limits are currently lacking. Further, safe charge densities that were classically determined from conical sharp electrodes are generalized for cylindrical (depth) and flat (surface grid) electrodes completely ignoring geometric factors that govern current spreading and trajectories in tissue.Approach. This work reports the first investigations comparing stimulation limits for clinically used electrodes in two mediums: in benchtop experiments in saline andin vivoin a single acute experiment in the pig brain. We experimentally determine the geometric factors, the water electrolysis windows, and the current safety limits from voltage transients, for the sEEG, depth and surface strip electrodes in both mediums. Using four-electrode and three-electrode configuration measurements and comprehensive circuit models that accurately depict our measurements, we delineate the various elements of the stimulation medium, including the tissue-electrode interface impedance spectra, the medium impedance and the bias-dependent change in the interface impedance as a function of stimulation parameters.Main results. The results of our systematics studies suggest that safe currents in clinical bipolar stimulation determinedin vivocan be as much as 24 times smaller than those determined from benchtop experiments (for depth electrodes at a 1 ms pulse duration). Our detailed circuit modeling attributes this drastic difference in safe limits to the greatly dissimilar electrode/tissue and electrode/saline impedances.Significance. We established the electrochemical safety limits for commonly used clinical electrodesin vivoand revealed by detailied electrochemical modeling how they differ from benchtop evaluation. We argue that electrochemical limits and currents are unique for each electrode, should be measuredin vivoaccording to the protocols established in this work, and should be accounted for while setting the stimulation parameters for clinical applications including for chronic applications.
Collapse
Affiliation(s)
- Ritwik Vatsyayan
- Integrated Electronics and Biointerfaces Laboratory, Department of Electrical and Computer Engineering, University of California, San Diego, CA 92093, United States of America
| | - Daniel Cleary
- Integrated Electronics and Biointerfaces Laboratory, Department of Electrical and Computer Engineering, University of California, San Diego, CA 92093, United States of America.,Department of Neurological Surgery, University of California, San Diego, CA 92097, United States of America
| | - Joel R Martin
- Integrated Electronics and Biointerfaces Laboratory, Department of Electrical and Computer Engineering, University of California, San Diego, CA 92093, United States of America.,Department of Neurological Surgery, University of California, San Diego, CA 92097, United States of America
| | - Eric Halgren
- Department of Radiology, University of California, San Diego, CA 92097, United States of America
| | - Shadi A Dayeh
- Integrated Electronics and Biointerfaces Laboratory, Department of Electrical and Computer Engineering, University of California, San Diego, CA 92093, United States of America
| |
Collapse
|
9
|
Soldozy S, Young S, Kumar JS, Capek S, Felbaum DR, Jean WC, Park MS, Syed HR. A systematic review of endovascular stent-electrode arrays, a minimally invasive approach to brain-machine interfaces. Neurosurg Focus 2020; 49:E3. [PMID: 32610291 DOI: 10.3171/2020.4.focus20186] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 04/20/2020] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The goal of this study was to systematically review the feasibility and safety of minimally invasive neurovascular approaches to brain-machine interfaces (BMIs). METHODS A systematic literature review was performed using the PubMed database for studies published between 1986 and 2019. All studies assessing endovascular neural interfaces were included. Additional studies were selected based on review of references of selected articles and review articles. RESULTS Of the 53 total articles identified in the original literature search, 12 studies were ultimately selected. An additional 10 articles were included from other sources, resulting in a total of 22 studies included in this systematic review. This includes primarily preclinical studies comparing endovascular electrode recordings with subdural and epidural electrodes, as well as studies evaluating stent-electrode gauge and material type. In addition, several clinical studies are also included. CONCLUSIONS Endovascular stent-electrode arrays provide a minimally invasive approach to BMIs. Stent-electrode placement has been shown to be both efficacious and safe, although further data are necessary to draw comparisons between subdural and epidural electrode measurements given the heterogeneity of the studies included. Greater access to deep-seated brain regions is now more feasible with stent-electrode arrays; however, further validation is needed in large clinical trials to optimize this neural interface. This includes the determination of ideal electrode material type, venous versus arterial approaches, the feasibility of deep brain stimulation, and more streamlined computational decoding techniques.
Collapse
Affiliation(s)
- Sauson Soldozy
- 1Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia
| | - Steven Young
- 1Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia
| | - Jeyan S Kumar
- 1Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia
| | - Stepan Capek
- 1Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia
| | - Daniel R Felbaum
- 2Department of Neurosurgery, Georgetown University, Washington, DC; and
| | - Walter C Jean
- 3Department of Neurosurgery, George Washington University, Washington, DC
| | - Min S Park
- 1Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia
| | - Hasan R Syed
- 1Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia
| |
Collapse
|
10
|
Cisnal A, R Ihmig F, Fraile JC, Pérez-Turiel J, Muñoz-Martinez V. Application of a Novel Measurement Setup for Characterization of Graphene Microelectrodes and a Comparative Study of Variables Influencing Charge Injection Limits of Implantable Microelectrodes. SENSORS 2019; 19:s19122725. [PMID: 31213039 PMCID: PMC6630677 DOI: 10.3390/s19122725] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 06/12/2019] [Accepted: 06/13/2019] [Indexed: 11/21/2022]
Abstract
Depending on their use, electrodes must have a certain size and design so as not to compromise their electrical characteristics. It is fundamental to be aware of all dependences on external factors that vary the electrochemical characteristics of the electrodes. When using implantable electrodes, the maximum charge injection capacity (CIC) is the total amount of charge that can be injected into the tissue in a reversible way. It is fundamental to know the relations between the characteristics of the microelectrode itself and its maximum CIC in order to develop microelectrodes that will be used in biomedical applications. CIC is a very complex measure that depends on many factors: material, size (geometric and effectiveness area), and shape of the implantable microelectrode and long-term behavior, composition, and temperature of the electrolyte. In this paper, our previously proposed measurement setup and automated calculation method are used to characterize a graphene microelectrode and to measure the behavior of a set of microelectrodes that have been developed in the Fraunhofer Institute for Biomedical Engineering (IBMT) labs. We provide an electrochemical evaluation of CIC for these microelectrodes by examining the role of the following variables: pulse width of the stimulation signal, electrode geometry and size, roughness factor, solution, and long-term behavior. We hope the results presented in this paper will be useful for future studies and for the manufacture of advanced implantable microelectrodes.
Collapse
Affiliation(s)
- Ana Cisnal
- ITAP-Universidad de Valladolid, Paseo del Cauce 59, 47011 Valladolid, Spain.
| | - Frank R Ihmig
- Department of Biomedical Microsystems, Fraunhofer-Institut für Biomedizinische Technik (IBMT), 66280 Sulzbach/Saar, Germany.
| | - Juan-Carlos Fraile
- ITAP-Universidad de Valladolid, Paseo del Cauce 59, 47011 Valladolid, Spain.
| | - Javier Pérez-Turiel
- ITAP-Universidad de Valladolid, Paseo del Cauce 59, 47011 Valladolid, Spain.
| | - Víctor Muñoz-Martinez
- Escuela de Ingenierías Industriales, Universidad de Málaga, Doctor Ortiz Ramos s/n, 29071 Málaga, Spain.
| |
Collapse
|