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Yi H, Kim H, Kim KR, Kim JH, Kim J, Lee H, Grewal SS, Freeman WD, Yeo WH. Flexible low-profile external ventricular drain catheter for real-time brain monitoring. Biosens Bioelectron 2024; 255:116267. [PMID: 38581838 DOI: 10.1016/j.bios.2024.116267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 03/27/2024] [Accepted: 04/01/2024] [Indexed: 04/08/2024]
Abstract
External ventricular drainage is one of the most common neurosurgical procedures in the world for acute hydrocephalus, which must be performed carefully by a neurosurgeon. Although various neuromonitoring external ventricular drain (EVD) catheters have been utilized, they still suffer from rigidity and bulkiness to mitigate post-EVD placement trauma. Here, we introduce a flexible and low-profile smart EVD catheter using a class of technologies with sensitive electrical materials, seamless integration, and flexible mechanics, which serves as a highly soft and minimally invasive device to monitor electrical brain signals. This device reliably captures biopotentials in real time while exhibiting remarkable flexibility and reliability. The seamless integration of its sensory system promises a minimally invasive EVD placement on brain tissue. This work validates the device's distinct characteristics and performances through in vitro experiments and computational analysis. Collectively, this device's exceptional patient- and user-friendly attributes highlight its potential as one of the most practical EVD catheters.
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Affiliation(s)
- Hoon Yi
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; IEN Center for Wearable Intelligent Systems and Healthcare Institute for Electronics and Nanotechnology, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Hodam Kim
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; IEN Center for Wearable Intelligent Systems and Healthcare Institute for Electronics and Nanotechnology, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Ka Ram Kim
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; IEN Center for Wearable Intelligent Systems and Healthcare Institute for Electronics and Nanotechnology, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Ju Hyeon Kim
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; IEN Center for Wearable Intelligent Systems and Healthcare Institute for Electronics and Nanotechnology, Georgia Institute of Technology, Atlanta, GA, 30332, USA; Department of Mechanical Engineering, Inha University, Incheon, 22212, Republic of Korea
| | - Juhee Kim
- Department of Mechanical System Engineering, Korea Military Academy, Seoul, 01805, Republic of Korea
| | - Hyunjae Lee
- Department of Mechanical Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Sanjeet S Grewal
- Department of Neurosurgery, Mayo Clinic, Jacksonville, FL, 32224, USA
| | - William D Freeman
- Department of Neurosurgery, Mayo Clinic, Jacksonville, FL, 32224, USA; Department of Neurology, Department of Critical Care Medicine, Mayo Clinic, Jacksonville, FL, 32224, USA
| | - Woon-Hong Yeo
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; IEN Center for Wearable Intelligent Systems and Healthcare Institute for Electronics and Nanotechnology, Georgia Institute of Technology, Atlanta, GA, 30332, USA; Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, GA, 30332, USA.
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2
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Colachis M, Schlink BR, Colachis S, Shqau K, Huegen BL, Palmer K, Heintz A. Benchtop Performance of Novel Mixed Ionic-Electronic Conductive Electrode Form Factors for Biopotential Recordings. SENSORS (BASEL, SWITZERLAND) 2024; 24:3136. [PMID: 38793990 PMCID: PMC11125343 DOI: 10.3390/s24103136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 05/02/2024] [Accepted: 05/10/2024] [Indexed: 05/26/2024]
Abstract
Background: Traditional gel-based (wet) electrodes for biopotential recordings have several shortcomings that limit their practicality for real-world measurements. Dry electrodes may improve usability, but they often suffer from reduced signal quality. We sought to evaluate the biopotential recording properties of a novel mixed ionic-electronic conductive (MIEC) material for improved performance. Methods: We fabricated four MIEC electrode form factors and compared their signal recording properties to two control electrodes, which are electrodes commonly used for biopotential recordings (Ag-AgCl and stainless steel). We used an agar synthetic skin to characterize the impedance of each electrode form factor. An electrical phantom setup allowed us to compare the recording quality of simulated biopotentials with ground-truth sources. Results: All MIEC electrode form factors yielded impedances in a similar range to the control electrodes (all <80 kΩ at 100 Hz). Three of the four MIEC samples produced similar signal-to-noise ratios and interfacial charge transfers as the control electrodes. Conclusions: The MIEC electrodes demonstrated similar and, in some cases, better signal recording characteristics than current state-of-the-art electrodes. MIEC electrodes can also be fabricated into a myriad of form factors, underscoring the great potential this novel material has across a wide range of biopotential recording applications.
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Affiliation(s)
- Matthew Colachis
- Battelle Memorial Institute, 505 King Ave., Columbus, OH 43201, USA; (B.R.S.); (K.S.); (K.P.); (A.H.)
| | - Bryan R. Schlink
- Battelle Memorial Institute, 505 King Ave., Columbus, OH 43201, USA; (B.R.S.); (K.S.); (K.P.); (A.H.)
| | - Sam Colachis
- Battelle Memorial Institute, 505 King Ave., Columbus, OH 43201, USA; (B.R.S.); (K.S.); (K.P.); (A.H.)
| | - Krenar Shqau
- Battelle Memorial Institute, 505 King Ave., Columbus, OH 43201, USA; (B.R.S.); (K.S.); (K.P.); (A.H.)
| | - Brittani L. Huegen
- UES, a BlueHalo Company, 4401 Dayton Xenia Road, Beavercreek, OH 45432, USA;
| | - Katherine Palmer
- Battelle Memorial Institute, 505 King Ave., Columbus, OH 43201, USA; (B.R.S.); (K.S.); (K.P.); (A.H.)
| | - Amy Heintz
- Battelle Memorial Institute, 505 King Ave., Columbus, OH 43201, USA; (B.R.S.); (K.S.); (K.P.); (A.H.)
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3
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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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4
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Lee D, Song J, Kim J, Lee J, Son D, Shin M. Soft and Conductive Polyethylene Glycol Hydrogel Electrodes for Electrocardiogram Monitoring. Gels 2023; 9:957. [PMID: 38131943 PMCID: PMC10742586 DOI: 10.3390/gels9120957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 12/03/2023] [Accepted: 12/04/2023] [Indexed: 12/23/2023] Open
Abstract
The measurement of biosignals in the clinical and healthcare fields is fundamental; however, conventional electrodes pose challenges such as incomplete skin contact and skin-related issues, hindering accurate biosignal measurement. To address these challenges, conductive hydrogels, which are valuable owing to their biocompatibility and flexibility, have been widely developed and explored for electrode applications. In this study, we fabricated a conductive hydrogel by mixing polyethylene glycol diacrylate (PEGDA) with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) polymers dissolved in deionized water, followed by light-triggered crosslinking. Notably, this study pioneered the use of a PEGDA-PEDOT:PSS hydrogel for electrocardiogram (ECG) monitoring- a type of biosignal. The resulting PEGDA-PEDOT:PSS hydrogel demonstrated remarkable conductivity while closely approximating the modulus of skin elasticity. Additionally, it demonstrated biocompatibility and a high signal-to-noise ratio in the waveforms. This study confirmed the exceptional suitability of the PEGDA-PEDOT:PSS hydrogel for accurate biosignal measurements with potential applications in various wearable devices designed for biosignal monitoring.
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Affiliation(s)
- Dongik Lee
- Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea; (D.L.); (J.K.); (J.L.)
| | - Jihyang Song
- Department of Artificial Intelligence System Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea;
| | - Jungwoo Kim
- Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea; (D.L.); (J.K.); (J.L.)
| | - Jaebeom Lee
- Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea; (D.L.); (J.K.); (J.L.)
| | - Donghee Son
- Department of Artificial Intelligence System Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea;
- Department of Electrical and Computer Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
| | - Mikyung Shin
- Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea; (D.L.); (J.K.); (J.L.)
- Department of Biomedical Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
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5
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Alahi MEE, Liu Y, Khademi S, Nag A, Wang H, Wu T, Mukhopadhyay SC. Slippery Epidural ECoG Electrode for High-Performance Neural Recording and Interface. BIOSENSORS 2022; 12:1044. [PMID: 36421162 PMCID: PMC9688081 DOI: 10.3390/bios12111044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 11/02/2022] [Accepted: 11/16/2022] [Indexed: 06/16/2023]
Abstract
Chronic implantation of an epidural Electrocorticography (ECoG) electrode produces thickening of the dura mater and proliferation of the fibrosis around the interface sites, which is a significant concern for chronic neural ECoG recording applications used to monitor various neurodegenerative diseases. This study describes a new approach to developing a slippery liquid-infused porous surface (SLIPS) on the flexible ECoG electrode for a chronic neural interface with the advantage of increased cell adhesion. In the demonstration, the electrode was fabricated on the polyimide (PI) substrate, and platinum (Pt)-gray was used for creating the porous nanocone structure for infusing the silicone oil. The combination of nanocone and the infused slippery oil layer created the SLIPS coating, which has a low impedance (4.68 kΩ) level favourable for neural recording applications. The electrochemical impedance spectroscopy and equivalent circuit modelling also showed the effect of the coating on the recording site. The cytotoxicity study demonstrated that the coating does not have any cytotoxic potentiality; hence, it is biocompatible for human implantation. The in vivo (acute recording) neural recording on the rat model also confirmed that the noise level could be reduced significantly (nearly 50%) and is helpful for chronic ECoG recording for more extended neural signal recording applications.
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Affiliation(s)
- Md Eshrat E. Alahi
- The Institute of Biomedical and Health Engineering, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Yonghong Liu
- The Institute of Biomedical and Health Engineering, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Sara Khademi
- The Institute of Biomedical and Health Engineering, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
- Institute of Polymeric Materials and Faculty of Polymer Engineering, Sahand University of Technology, Tabriz P.O. Box 51335/1996, Iran
| | - Anindya Nag
- Faculty of Electrical and Computer Engineering, Technische Universität Dresden, 01062 Dresden, Germany
- Centre for Tactile Internet with Human-in-the-Loop (CeTI), Technische Universität Dresden, 01069 Dresden, Germany
| | - Hao Wang
- The Institute of Biomedical and Health Engineering, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Tianzhun Wu
- The Institute of Biomedical and Health Engineering, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
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6
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Dong M, Coleman HA, Tonta MA, Xiong Z, Li D, Thomas S, Liu M, Fallon JB, Parkington HC, Forsythe JS. Rapid electrophoretic deposition of biocompatible graphene coatings for high-performance recording neural electrodes. NANOSCALE 2022; 14:15845-15858. [PMID: 36259692 DOI: 10.1039/d2nr04421h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The electrical and biological interfacial properties of invasive electrodes have a significant impact on the performance and longevity of neural recordings in the brain. In this study, we demonstrated rapid electrophoretic deposition and electrochemical reduction of graphene oxide (GO) on metal-based neural electrodes. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and other characterizations confirmed the existence of a uniform and effectively reduced graphene oxide coating. Electrochemically reduced graphene oxide (ErGO) coated Pt/Ir neural electrodes exhibited 15.2-fold increase in charge storage capacity (CSC) and 90% decrease in impedance with only 3.8% increase in electrode diameter. Patch clamp electrophysiology and calcium imaging of primary rat hippocampus neurons cultured on ErGO demonstrated that there was no adverse impact on the functional development of neurons. Immunostaining showed a balanced growth of excitatory and inhibitory neurons, and astrocytes. Acute recordings from the auditory cortex and chronic recordings (19 days) from the somatosensory cortex found ErGO coating improved the performance of neural electrodes in signal-to-noise ratio (SNR) and amplitude of signals. The proposed approach not only provides an in-depth evaluation of the effect of ErGO coating on neural electrodes but also widens the coating methods of commercial neural electrodes.
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Affiliation(s)
- Miheng Dong
- Department of Materials Science and Engineering, Monash Institute of Medical Engineering, Monash University, Clayton, VIC 3800, Australia.
- Monash Suzhou Research Institute, Monash University, Suzhou SIP 250000, China
| | - Harold A Coleman
- Department of Physiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
| | - Mary A Tonta
- Department of Physiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
| | - Zhiyuan Xiong
- Department of Chemical Engineering, University of Melbourne, Parkville, Victoria, Australia
| | - Dan Li
- Department of Chemical Engineering, University of Melbourne, Parkville, Victoria, Australia
| | - Sebastian Thomas
- Department of Materials Science and Engineering, Monash Institute of Medical Engineering, Monash University, Clayton, VIC 3800, Australia.
| | - Minsu Liu
- Department of Materials Science and Engineering, Monash Institute of Medical Engineering, Monash University, Clayton, VIC 3800, Australia.
- Monash Suzhou Research Institute, Monash University, Suzhou SIP 250000, China
- Foshan (Southern China) Institute for New Materials, Foshan 528200, China
| | - James B Fallon
- The Bionics Institute, East Melbourne, Victoria 3002, Australia
- Medical Bionics Department, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Helena C Parkington
- Department of Physiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
| | - John S Forsythe
- Department of Materials Science and Engineering, Monash Institute of Medical Engineering, Monash University, Clayton, VIC 3800, Australia.
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7
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Rao L, Liu Y, Zhou H. Significantly improved cell affinity of polydimethylsiloxane enabled by a surface-modified strategy with chemical coupling. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2022; 33:66. [PMID: 36138160 PMCID: PMC9499886 DOI: 10.1007/s10856-022-06690-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 08/27/2022] [Indexed: 06/16/2023]
Abstract
Polydimethylsiloxane (PDMS) is a commonly used insulation/packaging material for implantable neural electrodes. Nevertheless, the PDMS-initiated tissue response would lead to the deterioration of the electrode performances post-implantation, owing to its intrinsic hydrophobic and cell-repellent surface. The conventional physical coatings by hydrophilic hydrogels or bioactive molecules are unable to maintain during the long-term implantation due to their low stability by physical adhesion. In this work, we first anchor both hydrophilic polyethylene glycol (PEG) and bioactive molecule poly-L-lysine (PLL) on the PDMS surface by chemical coupling to change the PDMS surface from hydrophobic and cell-repellent to hydrophilic and cell-adhesive. XPS tests indicate the chemically coupled modification layers are stable on the PDMS surface after experiencing a harsh rinse process. Contact angle measurements show that the use of PEG 600 with the moderate molecular weight results in the highest hydrophilicity for the resulting PDMS-PEG-PLL. PC12 cell evaluation results exhibit that the PDMS-PEG-PLL with PEG 600 leads to significantly larger cell adhesion area, more neurite number, and longer neurite length than the PDMS. The PDMS-PEG-PLL with PEG 600 featuring stable modification layers, high hydrophilicity, and superior cell affinity has great potential in stabilizing the neural electrode-tissue interface for the long-term implantation. Graphical abstract.
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Affiliation(s)
- Li Rao
- Department of Geriatrics, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Yuqin Liu
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Molecular Science, Shanxi University, Taiyuan, 030006, China
| | - Haihan Zhou
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Molecular Science, Shanxi University, Taiyuan, 030006, China.
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8
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Kiang L, Woodington B, Carnicer-Lombarte A, Malliaras G, Barone DG. Spinal cord bioelectronic interfaces: opportunities in neural recording and clinical challenges. J Neural Eng 2022; 19. [PMID: 35320780 DOI: 10.1088/1741-2552/ac605f] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 03/23/2022] [Indexed: 11/11/2022]
Abstract
Bioelectronic stimulation of the spinal cord has demonstrated significant progress in restoration of motor function in spinal cord injury (SCI). The proximal, uninjured spinal cord presents a viable target for the recording and generation of control signals to drive targeted stimulation. Signals have been directly recorded from the spinal cord in behaving animals and correlated with limb kinematics. Advances in flexible materials, electrode impedance and signal analysis will allow SCR to be used in next-generation neuroprosthetics. In this review, we summarize the technological advances enabling progress in SCR and describe systematically the clinical challenges facing spinal cord bioelectronic interfaces and potential solutions, from device manufacture, surgical implantation to chronic effects of foreign body reaction and stress-strain mismatches between electrodes and neural tissue. Finally, we establish our vision of bi-directional closed-loop spinal cord bioelectronic bypass interfaces that enable the communication of disrupted sensory signals and restoration of motor function in SCI.
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Affiliation(s)
- Lei Kiang
- Orthopaedic Surgery, Singapore General Hospital, Outram Road, Singapore, Singapore, 169608, SINGAPORE
| | - Ben Woodington
- Department of Engineering, University of Cambridge, Electrical Engineering Division, 9 JJ Thomson Ave, Cambridge, Cambridge, CB2 1TN, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Alejandro Carnicer-Lombarte
- Clinical Neurosciences, University of Cambridge, Bioelectronics Laboratory, Cambridge, CB2 0PY, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - George Malliaras
- University of Cambridge, University of Cambridge, Cambridge, CB2 1TN, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Damiano G Barone
- Department of Engineering, University of Cambridge, Electrical Engineering Division, 9 JJ Thomson Ave, Cambridge, Cambridge, Cambridgeshire, CB2 1TN, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
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Czerwińska-Główka D, Skonieczna M, Barylski A, Golba S, Przystaś W, Zabłocka-Godlewska E, Student S, Cwalina B, Krukiewicz K. Bifunctional conducting polymer matrices with antibacterial and neuroprotective effects. Bioelectrochemistry 2021; 144:108030. [PMID: 34896782 DOI: 10.1016/j.bioelechem.2021.108030] [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: 08/23/2021] [Revised: 10/24/2021] [Accepted: 11/29/2021] [Indexed: 11/02/2022]
Abstract
Current trends in the field of neural tissue engineering include the design of advanced biomaterials combining excellent electrochemical performance with versatile biological characteristics. The purpose of this work was to develop an antibacterial and neuroprotective coating based on a conducting polymer - poly(3,4-ethylenedioxypyrrole) (PEDOP), loaded with an antibiotic agent - tetracycline (Tc). Employing an electrochemical technique to immobilize Tc within a growing polymer matrix allowed to fabricate robust PEDOP/Tc coatings with a high charge storage capacity (63.65 ± 6.05 mC/cm2), drug release efficiency (629.4 µg/cm2 ± 62.7 µg/cm2), and low charge transfer resistance (2.4 ± 0.1 kΩ), able to deliver a stable electrical signal. PEDOP/Tc were found to exhibit strong antimicrobial effects against Gram-negative bacteria Escherichia coli, expressed through negligible adhesion, reduction in viability, and a characteristic elongation of bacterial cells. Cytocompatibility and neuroprotective effects were evaluated using a rat neuroblastoma B35 cell line, and were analyzed using MTT, cell cycle, and Annexin-V apoptosis assays. The presence of Tc was found to enhance neural cell viability and neurite outgrowth. The results confirmed that PEDOP/Tc can serve as an efficient neural electrode coating able to enhance charge transfer, as well as to exhibit bifunctional biological characteristics, different for eukaryotic and prokaryotic cells.
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Affiliation(s)
- Dominika Czerwińska-Główka
- Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, M.Strzody 9, 44-100 Gliwice, Poland
| | - Magdalena Skonieczna
- Department of Systems Biology and Engineering, Faculty of Automatic Control, Electronics and Computer Science, Silesian University of Technology, Akademicka 16, 44-100 Gliwice, Poland; Biotechnology Centre, Silesian University of Technology, B. Krzywoustego 8, 44-100 Gliwice, Poland
| | - Adrian Barylski
- Institute of Materials Engineering, University of Silesia, 75 Pulku Piechoty, 41-500 Chorzow, Poland
| | - Sylwia Golba
- Institute of Materials Engineering, University of Silesia, 75 Pulku Piechoty, 41-500 Chorzow, Poland
| | - Wioletta Przystaś
- Biotechnology Centre, Silesian University of Technology, B. Krzywoustego 8, 44-100 Gliwice, Poland; Department of Air Protection, Faculty of Energy and Environmental Engineering, Silesian University of Technology, S. Konarskiego 22B, 44-100 Gliwice, Poland
| | - Ewa Zabłocka-Godlewska
- Biotechnology Centre, Silesian University of Technology, B. Krzywoustego 8, 44-100 Gliwice, Poland; Department of Air Protection, Faculty of Energy and Environmental Engineering, Silesian University of Technology, S. Konarskiego 22B, 44-100 Gliwice, Poland
| | - Sebastian Student
- Department of Systems Biology and Engineering, Faculty of Automatic Control, Electronics and Computer Science, Silesian University of Technology, Akademicka 16, 44-100 Gliwice, Poland; Biotechnology Centre, Silesian University of Technology, B. Krzywoustego 8, 44-100 Gliwice, Poland
| | - Beata Cwalina
- Biotechnology Centre, Silesian University of Technology, B. Krzywoustego 8, 44-100 Gliwice, Poland; Department of Environmental Biotechnology, Faculty of Energy and Environmental Engineering, Silesian University of Technology, S.Konarskiego 18, 44-100 Gliwice, Poland
| | - Katarzyna Krukiewicz
- Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, M.Strzody 9, 44-100 Gliwice, Poland.
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10
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Biocompatibility Testing of Liquid Metal as an Interconnection Material for Flexible Implant Technology. NANOMATERIALS 2021; 11:nano11123251. [PMID: 34947600 PMCID: PMC8706733 DOI: 10.3390/nano11123251] [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: 10/07/2021] [Revised: 11/16/2021] [Accepted: 11/25/2021] [Indexed: 11/23/2022]
Abstract
Galinstan, a liquid metal at room temperature, is a promising material for use in flexible electronics. Since it has been successfully integrated in devices for external use, e.g., as stretchable electronic skin in tactile sensation, the possibility of using galinstan for flexible implant technology comes to mind. Usage of liquid metals in a flexible implant would reduce the risk of broken conductive pathways in the implants and therefore reduce the possibility of implant failure. However, the biocompatibility of the liquid metal under study, i.e., galinstan, has not been proven in state-of-the-art literature. Therefore, in this paper, a material combination of galinstan and silicone rubber is under investigation regarding the success of sterilization methods and to establish biocompatibility testing for an in vivo application. First cell biocompatibility tests (WST-1 assays) and cell toxicity tests (LDH assays) show promising results regarding biocompatibility. This work paves the way towards the successful integration of stretchable devices using liquid metals embedded in a silicone rubber encapsulant for flexible surface electro-cortical grid arrays and other flexible implants.
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11
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Li H, Gao G, Xu Z, Tang D, Chen T. Recent Progress in Bionic Skin Based on Conductive Polymer Gels. Macromol Rapid Commun 2021; 42:e2100480. [PMID: 34505726 DOI: 10.1002/marc.202100480] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 08/30/2021] [Indexed: 12/12/2022]
Abstract
Bionic skin sensors based on conductive polymer gels have garnered interest for their potential applications in human-computer interaction, soft robotics, biomedical systems, sports, and healthcare, because of their intrinsic flexibility and stretchability embedded at the material level, and other such as self-healing, adhesion, high, and low temperature tolerance properties that can be tuned through macromolecular design. Here, important advances in polymer gel-based flexible sensors over recent years are summarized, from material design, sensor fabrication to system-level applications. This review focuses on the representative strategies of design and preparing of conductive polymer gels, and adjusting their conductivity, mechanics, and other properties such as self-healing and adhesiveness by controlling the macromolecular network structures. The state-of-art of present flexible pressure and strain sensors, temperature sensors, position sensors, and multifunctional sensors based on capacitance, voltage, and resistance sensing technologies, are also systematically reviewed. Finally, perspectives on issues regarding further advances and challenges are provided.
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Affiliation(s)
- Huijing Li
- Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China.,School of Chemical Science, University of Chinese Academy of Sciences, 9A Yuquan Road, Beijing, 100049, China
| | - Guorong Gao
- Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China.,School of Chemical Science, University of Chinese Academy of Sciences, 9A Yuquan Road, Beijing, 100049, China
| | - Zhenyu Xu
- Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China.,School of Chemical Science, University of Chinese Academy of Sciences, 9A Yuquan Road, Beijing, 100049, China
| | - Diane Tang
- YK Pao School, No 1800, Lane 900 North Sanxin Road, Songjiang District, Shanghai, 201620, China
| | - Tao Chen
- Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China.,School of Chemical Science, University of Chinese Academy of Sciences, 9A Yuquan Road, Beijing, 100049, China
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12
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Zheng XS, Yang Q, Vazquez AL, Tracy Cui X. Imaging the Efficiency of Poly(3,4-ethylenedioxythiophene) Doped with Acid-Functionalized Carbon Nanotube and Iridium Oxide Electrode Coatings for Microstimulation. ADVANCED NANOBIOMED RESEARCH 2021; 1:2000092. [PMID: 34746928 PMCID: PMC8552016 DOI: 10.1002/anbr.202000092] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 03/18/2021] [Indexed: 12/02/2022] Open
Abstract
Electrical microstimulation has shown promise in restoring neural deficits in humans. Electrodes coated with materials like the conducting polymer poly(3,4-ethylenedioxythiophene) doped with acid-functionalized carbon nanotubes (PEDOT/CNTs, or PC) exhibit superior charge injection than traditional metals like platinum. However, the stimulation performance of PC remains to be fully characterized. Advanced imaging techniques and transgenic tools allow for real-time observations of neural activity in vivo. Herein, microelectrodes coated with PC and iridium oxide (IrOx) (a commonly used high-charge-injection material) are implanted in GCaMP6s mice and electrical stimulation is applied while imaging neuronal calcium responses. Results show that PC-coated electrodes stimulate more intense and broader GCaMP responses than IrOx. Two-photon microscopy reveals that PC-coated electrodes activate significantly more neuronal soma and neuropil than IrOx-coated electrodes in constant-voltage stimulation and significantly more neuronal soma in constant-current stimulation. Furthermore, with the same injected charge, both materials activate more spatially confined neural elements with shorter pulses than longer pulses, providing a means to tune stimulation selectivity. Finite element analyses reveal that the PC coating creates a denser and nonuniform electric field, increasing the likelihood of activating nearby neural elements. PC coating can significantly improve energy efficiency for electrical stimulation applications.
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Affiliation(s)
- Xin S. Zheng
- Department of BioengineeringUniversity of Pittsburgh3501 Fifth Ave.PittsburghPA15213USA
| | - Qianru Yang
- Department of BioengineeringUniversity of Pittsburgh3501 Fifth Ave.PittsburghPA15213USA
| | - Alberto L. Vazquez
- Departments of Radiology and BioengineeringUniversity of Pittsburgh3025 E. Carson St.PittsburghPA15203USA
| | - Xinyan Tracy Cui
- Department of BioengineeringUniversity of Pittsburgh3501 Fifth Ave.PittsburghPA15213USA
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13
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Delfino E, Pastore A, Zucchini E, Cruz MFP, Ius T, Vomero M, D'Ausilio A, Casile A, Skrap M, Stieglitz T, Fadiga L. Prediction of Speech Onset by Micro-Electrocorticography of the Human Brain. Int J Neural Syst 2021; 31:2150025. [PMID: 34130614 DOI: 10.1142/s0129065721500258] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Recent technological advances show the feasibility of offline decoding speech from neuronal signals, paving the way to the development of chronically implanted speech brain computer interfaces (sBCI). Two key steps that still need to be addressed for the online deployment of sBCI are, on the one hand, the definition of relevant design parameters of the recording arrays, on the other hand, the identification of robust physiological markers of the patient's intention to speak, which can be used to online trigger the decoding process. To address these issues, we acutely recorded speech-related signals from the frontal cortex of two human patients undergoing awake neurosurgery for brain tumors using three different micro-electrocorticographic ([Formula: see text]ECoG) devices. First, we observed that, at the smallest investigated pitch (600[Formula: see text][Formula: see text]m), neighboring channels are highly correlated, suggesting that more closely spaced electrodes would provide some redundant information. Second, we trained a classifier to recognize speech-related motor preparation from high-gamma oscillations (70-150[Formula: see text]Hz), demonstrating that these neuronal signals can be used to reliably predict speech onset. Notably, our model generalized both across subjects and recording devices showing the robustness of its performance. These findings provide crucial information for the design of future online sBCI.
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Affiliation(s)
- Emanuela Delfino
- Center for Translational Neurophysiology, Istituto Italiano di Tecnologia, Via Fossato di Mortara 17-19, Ferrara 44121, Italy.,Section of Physiology, University of Ferrara, Via Fossato di Mortara 17-19, Ferrara 44121, Italy
| | - Aldo Pastore
- Center for Translational Neurophysiology, Istituto Italiano di Tecnologia, Via Fossato di Mortara 17-19, Ferrara 44121, Italy.,Section of Physiology, University of Ferrara, Via Fossato di Mortara 17-19, Ferrara 44121, Italy
| | - Elena Zucchini
- Center for Translational Neurophysiology, Istituto Italiano di Tecnologia, Via Fossato di Mortara 17-19, Ferrara 44121, Italy.,Section of Physiology, University of Ferrara, Via Fossato di Mortara 17-19, Ferrara 44121, Italy
| | - Maria Francisca Porto Cruz
- Center for Translational Neurophysiology, Istituto Italiano di Tecnologia, Via Fossato di Mortara 17-19, Ferrara 44121, Italy.,Section of Physiology, University of Ferrara, Via Fossato di Mortara 17-19, Ferrara 44121, Italy.,Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering (IMTEK), University of Freiburg, Georges-Köhler-Allee 102, Freiburg im Breisgau 79110, Germany
| | - Tamara Ius
- Struttura Complessa di Neurochirurgia, Azienda Ospedaliero-Universitaria Santa Maria, della Misericordia, Piazzale Santa Maria, della Misericordia 15, Udine 33100, Italy
| | - Maria Vomero
- Bioelectronic Systems Laboratory, Columbia University, 500 West 120th Street, New York, NY 10027, USA
| | - Alessandro D'Ausilio
- Center for Translational Neurophysiology, Istituto Italiano di Tecnologia, Via Fossato di Mortara 17-19, Ferrara 44121, Italy.,Section of Physiology, University of Ferrara, Via Fossato di Mortara 17-19, Ferrara 44121, Italy
| | - Antonino Casile
- Center for Translational Neurophysiology, Istituto Italiano di Tecnologia, Via Fossato di Mortara 17-19, Ferrara 44121, Italy
| | - Miran Skrap
- Struttura Complessa di Neurochirurgia, Azienda Ospedaliero-Universitaria Santa Maria, della Misericordia, Piazzale Santa Maria, della Misericordia 15, Udine 33100, Italy
| | - Thomas Stieglitz
- Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering (IMTEK), University of Freiburg, Georges-Köhler-Allee 102, Freiburg im Breisgau 79110, Germany.,BrainLinks-BrainTools Center, University of Freiburg, Georges-Köhler-Allee 80, Freiburg im Breisgau 79110, Germany
| | - Luciano Fadiga
- Center for Translational Neurophysiology, Istituto Italiano di Tecnologia, Via Fossato di Mortara 17-19, Ferrara 44121, Italy.,Section of Physiology, University of Ferrara, Via Fossato di Mortara 17-19, Ferrara 44121, Italy
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14
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Zheng XS, Tan C, Castagnola E, Cui XT. Electrode Materials for Chronic Electrical Microstimulation. Adv Healthc Mater 2021; 10:e2100119. [PMID: 34029008 PMCID: PMC8257249 DOI: 10.1002/adhm.202100119] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 04/20/2021] [Indexed: 02/06/2023]
Abstract
Electrical microstimulation has enabled partial restoration of vision, hearing, movement, somatosensation, as well as improving organ functions by electrically modulating neural activities. However, chronic microstimulation is faced with numerous challenges. The implantation of an electrode array into the neural tissue triggers an inflammatory response, which can be exacerbated by the delivery of electrical currents. Meanwhile, prolonged stimulation may lead to electrode material degradation., which can be accelerated by the hostile inflammatory environment. Both material degradation and adverse tissue reactions can compromise stimulation performance over time. For stable chronic electrical stimulation, an ideal microelectrode must present 1) high charge injection limit, to efficiently deliver charge without exceeding safety limits for both tissue and electrodes, 2) small size, to gain high spatial selectivity, 3) excellent biocompatibility that ensures tissue health immediately next to the device, and 4) stable in vivo electrochemical properties over the application period. In this review, the challenges in chronic microstimulation are described in detail. To aid material scientists interested in neural stimulation research, the in vitro and in vivo testing methods are introduced for assessing stimulation functionality and longevity and a detailed overview of recent advances in electrode material research and device fabrication for improving chronic microstimulation performance is provided.
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Affiliation(s)
- Xin Sally Zheng
- Department of Bioengineering, University of Pittsburgh, 3501 Fifth Ave. Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Chao Tan
- Department of Bioengineering, University of Pittsburgh, 3501 Fifth Ave. Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Elisa Castagnola
- Department of Bioengineering, University of Pittsburgh, 3501 Fifth Ave. Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Xinyan Tracy Cui
- Department of Bioengineering, University of Pittsburgh, 3501 Fifth Ave. Pittsburgh, Pittsburgh, PA, 15213, USA
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15
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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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16
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Tia B, Takemi M, Kosugi A, Castagnola E, Ricci D, Ushiba J, Fadiga L, Iriki A. Spectral Power in Marmoset Frontal Motor Cortex during Natural Locomotor Behavior. Cereb Cortex 2020; 31:1077-1089. [PMID: 33068002 PMCID: PMC7786367 DOI: 10.1093/cercor/bhaa275] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 08/25/2020] [Accepted: 08/25/2020] [Indexed: 12/15/2022] Open
Abstract
During primate arboreal locomotion, substrate orientation modifies body axis orientation and biomechanical contribution of fore- and hindlimbs. To characterize the role of cortical oscillations in integrating these locomotor demands, we recorded electrocorticographic activity from left dorsal premotor, primary motor, and supplementary motor cortices of three common marmosets moving across a branch-like small-diameter pole, fixed horizontally or vertically. Animals displayed behavioral adjustments to the task, namely, the horizontal condition mainly induced quadrupedal walk with pronated/neutral forelimb postures, whereas the vertical condition induced walk and bound gaits with supinated/neutral postures. Examination of cortical activity suggests that β (16–35 Hz) and γ (75–100 Hz) oscillations could reflect different processes in locomotor adjustments. During task, modulation of γ ERS by substrate orientation (horizontal/vertical) and epoch (preparation/execution) suggests close tuning to movement dynamics and biomechanical demands. β ERD was essentially modulated by gait (walk/bound), which could illustrate contribution to movement sequence and coordination. At rest, modulation of β power by substrate orientation underlines its role in sensorimotor processes for postural maintenance.
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Affiliation(s)
- Banty Tia
- Laboratory for Symbolic Cognitive Development, RIKEN Center for Biosystems Dynamics Research, Kobe, 650-0047, Japan.,Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di Tecnologia, Ferrara, 44121, Italy
| | - Mitsuaki Takemi
- Laboratory for Symbolic Cognitive Development, RIKEN Center for Biosystems Dynamics Research, Kobe, 650-0047, Japan.,Graduate School of Science and Technology, Keio University, Yokohama, 223-8522, Japan.,Graduate School of Education, The University of Tokyo, Tokyo, 113-8654, Japan.,Japan Science and Technology Agency, PRESTO, Saitama, 332-0012, Japan
| | - Akito Kosugi
- Laboratory for Symbolic Cognitive Development, RIKEN Center for Biosystems Dynamics Research, Kobe, 650-0047, Japan.,Graduate School of Science and Technology, Keio University, Yokohama, 223-8522, Japan
| | - Elisa Castagnola
- Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di Tecnologia, Ferrara, 44121, Italy
| | - Davide Ricci
- Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di Tecnologia, Ferrara, 44121, Italy
| | - Junichi Ushiba
- Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Yokohama, 223-8522, Japan
| | - Luciano Fadiga
- Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di Tecnologia, Ferrara, 44121, Italy.,Section of Physiology, University of Ferrara, Ferrara, 44121, Italy
| | - Atsushi Iriki
- Laboratory for Symbolic Cognitive Development, RIKEN Center for Biosystems Dynamics Research, Kobe, 650-0047, Japan
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17
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Khalifa A, Liu Y, Bao Z, Etienne-Cummings R. A Compact Free-Floating Device for Passive Charge-Balanced Neural Stimulation using PEDOT/CNT microelectrodes. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2020:3375-3378. [PMID: 33018728 DOI: 10.1109/embc44109.2020.9176643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Wirelessly powered implants are increasingly being developed as free-floating single-channel devices to interface with neurons directly at stimulation sites. In order to stimulate neurons in a manner that is safe to both the electrode and the surrounding tissue, charge accumulation over time needs to be avoided. The implementation of conventional charge balancing methods often leads to an increase in system complexity, power consumption or area, all of which are critical parameters in ultra-small wireless devices. The proposed charge balancing method described in this work, which relies on bipolar capacitive integrated electrodes, does not increase these parameters. The standalone wirelessly powered stimulating implant is implemented in a 130nm CMOS technology and measures 0.009 mm3.
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18
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Park H, Maple AR, Lee H. Effects of Fractal Electrode Geometry in Charge Injection Capacity of TiN Microelectrodes. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2020:3371-3374. [PMID: 33018727 DOI: 10.1109/embc44109.2020.9176725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Microelectrodes are basic tools for investigating small-scale brain dynamics. Noble metals such as gold (Au), platinum (Pt), and iridium oxide (IrOx) have been used as an electrode material because of their biocompatibility and good charge transfer capability. Their main charge transfer mechanism is the Faradaic process with redox reactions. Unfortunately, the decrease in electrode size accelerates the irreversible electrochemical dissolution during electrical stimulation due to increased current density. The dissolution can be prevented by alternating the electrode material to capacitive charge injection materials such as titanium nitride (TiN). However, electrical conductivity of TiN is relatively lower than the noble metals, which results in a lower charge injection capability. Therefore, there is a need to increase the charge injection limit of TiN electrodes for a high-performing neurostimulation. Our previous work suggested that the Vicseck fractal design can increase the charge injection limit of the microelectrodes. In this work, the effects of the fractal design in capacitive charge injection material were experimentally investigated by using TiN microelectrodes with circular and fractal designs. We measured the cyclic voltammetry, electrochemical impedance spectroscopy, and voltage transients. In addition, the charge injection limits of theses microelectrodes were estimated to quantify the effects of planar geometry on TiN microelectrodes. Despite our previous results showing superior charge injection capability of fractal Pt microelectrodes, the TiN showed no significant improvements due to the fractal geometry. This may be because the increase in charge injection capability of fractal microelectrodes is due to increased Faradaic charge injection process, which is minimized for TiN materials. Thus, our data suggests that the material as well as the geometry of the microelectrodes play key roles in optimizing stimulation microelectrode performance.Clinical relevance-As with the Faradaic charge injection-dominant materials, the capacitive charge injection materials could also benefit from additional investigation to fully characterize effects of electrode geometry for improved neurostimulation performance.
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19
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Guo L. Perspectives on electrical neural recording: a revisit to the fundamental concepts. J Neural Eng 2020; 17:013001. [PMID: 31986493 DOI: 10.1088/1741-2552/ab702f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE This paper aims to promote understanding on the fundamental concepts and mechanisms of extracellular electrical neural recording. APPROACH First, the electrode-electrolyte interface is reviewed to clarify some of the frequent misunderstandings. Second, analytical solutions to the extracellular field potential and recorded signal are derived based on equivalent electrical circuit models, using a planar substrate microelectrode as a particular example. And third, factors affecting the recording quality are thoroughly assessed. MAIN RESULTS Passive neural recording electrodes function as a pure capacitor. The extracellular field potential has two phases, with its subthreshold depolarization phase proportional to the first time derivative of the membrane depolarization and its action potential phase proportional to the negative first time derivative of the intracellular action potential. The recorded signal represents a portion of the extracellular field potential with both amplitude attenuation and phase distortion according to a voltage-divider circuit formed between the recording electrode and amplifier. A larger cell, a larger cell-substrate junctional membrane area, and a tighter membrane-substrate seal all help to improve the recording quality, while the effective electrode impedance should be minimized and the effective amplifier's input impedance maximized. SIGNIFICANCE This paper develops in-depth insights to offer a clear image on the recording mechanism, nature of the signal, and interplays between key interface parameters. This work will make a foundational contribution to the field by providing such an in-depth understanding on this topic to clear the widespread ambiguities and confusions and inform rational neural electrode designs and proper interpretations of neural recordings.
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Affiliation(s)
- Liang Guo
- Department of Electrical and Computer Engineering, The Ohio State University, Columbus, OH, United States of America. Department of Neuroscience, The Ohio State University, Columbus, OH, United States of America
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20
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Khalifa A, Liu Y, Karimi Y, Wang Q, Eisape A, Stanacevic M, Thakor N, Bao Z, Etienne-Cummings R. The Microbead: A 0.009 mm 3 Implantable Wireless Neural Stimulator. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2019; 13:971-985. [PMID: 31484132 DOI: 10.1109/tbcas.2019.2939014] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Wirelessly powered implants are increasingly being developed to interface with neurons in the brain. They often rely on microelectrode arrays, which are limited by their ability to cover large cortical surface areas and long-term stability because of their physical size and rigid configuration. Yet some clinical and research applications prioritize a distributed neural interface over one that offers high channel count. One solution to make large scale, fully specifiable, electrical stimulation/recording possible, is to disconnect the electrodes from the base, so that they can be arbitrarily placed freely in the nervous system. In this work, a wirelessly powered stimulating implant is miniaturized using a novel electrode integration technique, and its implanted depth maximized using new optimization design methods for the transmitter and receiver coils. The stimulating device is implemented in a 130 nm CMOS technology with the following characteristics: 300 μm × 300 μm × 80 μm size; optimized two-coil inductive link; and integrated circuit, electrodes and coil. The wireless and stimulation capability of the implant is demonstrated in a conductive medium, as well as in-vivo. To the best of our knowledge, the fabricated free-floating miniaturized implant has the best depth-to-volume ratio making it an excellent tool for minimally-invasive distributed neural interface, and thus could eventually complement or replace the rigid arrays that are currently the state-of-the-art in brain set-ups.
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21
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Carli S, Bianchi M, Zucchini E, Di Lauro M, Prato M, Murgia M, Fadiga L, Biscarini F. Electrodeposited PEDOT:Nafion Composite for Neural Recording and Stimulation. Adv Healthc Mater 2019; 8:e1900765. [PMID: 31489795 DOI: 10.1002/adhm.201900765] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 08/09/2019] [Indexed: 01/12/2023]
Abstract
Microelectrode arrays are used for recording and stimulation in neurosciences both in vitro and in vivo. The electrodeposition of conductive polymers, such as poly(3,4-ethylene dioxythiophene) (PEDOT), is widely adopted to improve both the in vivo recording and the charge injection limit of metallic microelectrodes. The workhorse of conductive polymers in the neurosciences is PEDOT:PSS, where PSS represents polystyrene-sulfonate. In this paper, the counterion is the fluorinated polymer Nafion, so the composite PEDOT:Nafion is deposited onto a flexible neural microelectrode array. PEDOT:Nafion coated electrodes exhibit comparable in vivo recording capability to the reference PEDOT:PSS, providing a large signal-to-noise ratio in a murine animal model. Importantly, PEDOT:Nafion exhibits a minimized polarization during electrical stimulation, thereby resulting in an improved charge injection limit equal to 4.4 mC cm-2 , almost 80% larger than the 2.5 mC cm-2 that is observed for PEDOT:PSS.
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Affiliation(s)
- Stefano Carli
- Center for Translational Neurophysiology of Speech and CommunicationIstituto Italiano di Tecnologia 44121 Ferrara Italy
| | - Michele Bianchi
- Center for Translational Neurophysiology of Speech and CommunicationIstituto Italiano di Tecnologia 44121 Ferrara Italy
| | - Elena Zucchini
- Center for Translational Neurophysiology of Speech and CommunicationIstituto Italiano di Tecnologia 44121 Ferrara Italy
- Section of Human PhysiologyUniversity of Ferrara 44121 Ferrara Italy
| | - Michele Di Lauro
- Center for Translational Neurophysiology of Speech and CommunicationIstituto Italiano di Tecnologia 44121 Ferrara Italy
| | - Mirko Prato
- Materials Characterization FacilityIstituto Italiano di Tecnologia 16163 Genova Italy
| | - Mauro Murgia
- Istituto per lo Studio dei Materiali Nanostrutturati (ISMN)CNR 40129 Bologna Italy
| | - Luciano Fadiga
- Center for Translational Neurophysiology of Speech and CommunicationIstituto Italiano di Tecnologia 44121 Ferrara Italy
- Section of Human PhysiologyUniversity of Ferrara 44121 Ferrara Italy
| | - Fabio Biscarini
- Center for Translational Neurophysiology of Speech and CommunicationIstituto Italiano di Tecnologia 44121 Ferrara Italy
- Department of Life SciencesUniversity of Modena and Reggio Emilia 41125 Modena Italy
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22
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Feig VR, Tran H, Lee M, Liu K, Huang Z, Beker L, Mackanic DG, Bao Z. An Electrochemical Gelation Method for Patterning Conductive PEDOT:PSS Hydrogels. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1902869. [PMID: 31414520 DOI: 10.1002/adma.201902869] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 07/28/2019] [Indexed: 05/20/2023]
Abstract
Due to their high water content and macroscopic connectivity, hydrogels made from the conducting polymer PEDOT:PSS are a promising platform from which to fabricate a wide range of porous conductive materials that are increasingly of interest in applications as varied as bioelectronics, regenerative medicine, and energy storage. Despite the promising properties of PEDOT:PSS-based porous materials, the ability to pattern PEDOT:PSS hydrogels is still required to enable their integration with multifunctional and multichannel electronic devices. In this work, a novel electrochemical gelation ("electrogelation") method is presented for rapidly patterning PEDOT:PSS hydrogels on any conductive template, including curved and 3D surfaces. High spatial resolution is achieved through use of a sacrificial metal layer to generate the hydrogel pattern, thereby enabling high-performance conducting hydrogels and aerogels with desirable material properties to be introduced into increasingly complex device architectures.
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Affiliation(s)
- Vivian Rachel Feig
- Department of Materials Science and Engineering, Stanford University, 443 Via Ortega, Room 328, Stanford, CA, 93405, USA
| | - Helen Tran
- Department of Chemical Engineering, Stanford University, 443 Via Ortega, Room 328, Stanford, CA, 93405, USA
| | - Minah Lee
- Center for Energy Storage Research, Clean Energy Institute, Korea Institute of Science and Technology (KIST), Seoul, 02792, Korea
| | - Kathy Liu
- Department of Materials Science and Engineering, Stanford University, 443 Via Ortega, Room 328, Stanford, CA, 93405, USA
| | - Zhuojun Huang
- Department of Materials Science and Engineering, Stanford University, 443 Via Ortega, Room 328, Stanford, CA, 93405, USA
| | - Levent Beker
- Department of Mechanical Engineering, Koç University Rumelifeneri Yolu, Sarıyer, İstanbul, 34450, Turkey
| | - David G Mackanic
- Department of Chemical Engineering, Stanford University, 443 Via Ortega, Room 328, Stanford, CA, 93405, USA
| | - Zhenan Bao
- Department of Chemical Engineering, Stanford University, 443 Via Ortega, Room 328, Stanford, CA, 93405, USA
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23
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Kosugi A, Castagnola E, Carli S, Ricci D, Fadiga L, Taoka M, Iriki A, Ushiba J. Fast Electrophysiological Mapping of Rat Cortical Motor Representation on a Time Scale of Minutes during Skin Stimulation. Neuroscience 2019; 414:245-254. [PMID: 31301365 DOI: 10.1016/j.neuroscience.2019.07.011] [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: 11/26/2018] [Revised: 07/01/2019] [Accepted: 07/02/2019] [Indexed: 10/26/2022]
Abstract
The topographic map of motor cortical representation, called the motor map, is not invariant, but can be altered by motor learning, neurological injury, and functional recovery from injury. Although much attention has been paid to short-term changes of the motor map, robust measures have not been established. The existing mapping methods are time-consuming, and the obtained maps are confounded by time preference. The purpose of this study was to examine the dynamics of the motor map on a timescale of minutes during transient somatosensory input by a fast motor mapping technique. We applied 32-channel micro-electrocorticographic electrode arrays to the rat sensorimotor cortex for cortical stimulation, and the topographic profile of motor thresholds in forelimb muscle was identified by fast motor mapping. Sequential motor maps were obtained every few minutes before, during, and just after skin stimulation to the dorsal forearm using a wool buff. During skin stimulation, the motor map expanded and the center of gravity of the map was shifted caudally. The expansion of the map persisted for at least a few minutes after the end of skin stimulation. Although the motor threshold of the hotspot was not changed, the area in which it was decreased appeared caudally to the hotspot, which may be in the somatosensory cortex. The present study demonstrated rapid enlargement of the forelimb motor map in the order of a few minutes induced by skin stimulation. This helps to understand the spatial dynamism of motor cortical representation that is modulated rapidly by somatosensory input.
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Affiliation(s)
- Akito Kosugi
- Graduate School of Science and Technology, Keio University, Kanagawa, Japan; Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Saitama, Japan; Laboratory for Symbolic Cognitive Development, RIKEN Center for Biosystems Dynamics Research, Saitama, Japan
| | - Elisa Castagnola
- Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di Tecnologia, Ferrara, Italy; Center for Sensorimotor Neural Engineering, San Diego State University, San Diego, CA, United States
| | - Stefano Carli
- Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di Tecnologia, Ferrara, Italy
| | - Davide Ricci
- Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di Tecnologia, Ferrara, Italy
| | - Luciano Fadiga
- Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di Tecnologia, Ferrara, Italy; Section of Human Physiology, University of Ferrara, Ferrara, Italy
| | - Miki Taoka
- Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Saitama, Japan; Laboratory for Symbolic Cognitive Development, RIKEN Center for Biosystems Dynamics Research, Saitama, Japan
| | - Atsushi Iriki
- Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Saitama, Japan; Laboratory for Symbolic Cognitive Development, RIKEN Center for Biosystems Dynamics Research, Saitama, Japan
| | - Junichi Ushiba
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, Kanagawa, Japan; Keio Institute of Pure and Applied Sciences, Keio University, Kanagawa, Japan.
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24
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Xu K, Li S, Dong S, Zhang S, Pan G, Wang G, Shi L, Guo W, Yu C, Luo J. Bioresorbable Electrode Array for Electrophysiological and Pressure Signal Recording in the Brain. Adv Healthc Mater 2019; 8:e1801649. [PMID: 31168937 DOI: 10.1002/adhm.201801649] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 03/29/2019] [Indexed: 01/29/2023]
Abstract
Medical implantation of an electrocorticography (ECoG) recording system for brain monitoring is an effective clinical tool for seizure focus location and brain disease diagnosis. Planar and flexible ECoG electrodes can minimize the risks of infection and serious inflammatory response, and their good shape adaptability allows the device to fit complex cortex shape and structure to record brain signals with high spatial and temporal resolution. However, these ECoG electrodes require an additional surgery to remove the implant, which imposes potential medical risks. Here, a novel flexible and bioresorbable ECoG device integrated with an intracortical pressure sensor for monitoring swelling of the cortex during operation is reported. The ECoG device is fabricated with poly(l-lactide) and polycaprolactone composite and transient metal molybdenum. In vivo tests on rats show that the ECoG system can record the dynamic changes in brain signals for the different epilepsy stages with high resolution, while the malleable pressure sensor shows a linear relationship between the pressure and resistance in in vitro tests. In vitro degradation experiments show that the ECoG system can work stably for about five days before loss of efficacy, and the whole ECoG system degrades completely in a phosphate buffer solution in about 100 days.
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Affiliation(s)
- Kedi Xu
- Key Laboratory of Biomedical Engineering of Education MinistryQiushi Academy for Advanced StudiesDepartment of Biomedical EngineeringZhejiang University Hangzhou 310027 China
| | - Shijian Li
- College of Computer ScienceZhejiang University Hangzhou 310027 China
| | - Shurong Dong
- College of Information Science and Electronic EngineeringZhejiang University Hangzhou 310027 China
| | - Shaomin Zhang
- Key Laboratory of Biomedical Engineering of Education MinistryQiushi Academy for Advanced StudiesDepartment of Biomedical EngineeringZhejiang University Hangzhou 310027 China
| | - Gang Pan
- College of Computer ScienceZhejiang University Hangzhou 310027 China
| | - Guangming Wang
- College of Information Science and Electronic EngineeringZhejiang University Hangzhou 310027 China
| | - Lin Shi
- College of Information Science and Electronic EngineeringZhejiang University Hangzhou 310027 China
| | - Wei Guo
- College of Information Science and Electronic EngineeringZhejiang University Hangzhou 310027 China
| | - Chaonan Yu
- Key Laboratory of Biomedical Engineering of Education MinistryQiushi Academy for Advanced StudiesDepartment of Biomedical EngineeringZhejiang University Hangzhou 310027 China
| | - Jikui Luo
- Institute of Renewable Energy and Environmental TechnologyBolton University Deane Road Bolton BL3 5AB UK
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25
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Decataldo F, Cramer T, Martelli D, Gualandi I, Korim WS, Yao ST, Tessarolo M, Murgia M, Scavetta E, Amici R, Fraboni B. Stretchable Low Impedance Electrodes for Bioelectronic Recording from Small Peripheral Nerves. Sci Rep 2019; 9:10598. [PMID: 31332219 PMCID: PMC6646361 DOI: 10.1038/s41598-019-46967-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 07/03/2019] [Indexed: 12/24/2022] Open
Abstract
Monitoring of bioelectric signals in peripheral sympathetic nerves of small animal models is crucial to gain understanding of how the autonomic nervous system controls specific body functions related to disease states. Advances in minimally-invasive electrodes for such recordings in chronic conditions rely on electrode materials that show low-impedance ionic/electronic interfaces and elastic mechanical properties compliant with the soft and fragile nerve strands. Here we report a highly stretchable low-impedance electrode realized by microcracked gold films as metallic conductors covered with stretchable conducting polymer composite to facilitate ion-to-electron exchange. The conducting polymer composite based on poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) obtains its adhesive, low-impedance properties by controlling thickness, plasticizer content and deposition conditions. Atomic Force Microscopy measurements under strain show that the optimized conducting polymer coating is compliant with the micro-crack mechanics of the underlying Au-layer, necessary to absorb the tensile deformation when the electrodes are stretched. We demonstrate functionality of the stretchable electrodes by performing high quality recordings of renal sympathetic nerve activity under chronic conditions in rats.
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Affiliation(s)
| | - Tobias Cramer
- Department of Physics and Astronomy, University of Bologna, Bologna, Italy.
| | - Davide Martelli
- Department of Biomedical and Neuromotor Sciences - Physiology, University of Bologna, Bologna, Italy
| | - Isacco Gualandi
- Department of Industrial Chemistry, University of Bologna, Bologna, Italy
| | - Willian S Korim
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - Song T Yao
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - Marta Tessarolo
- Department of Physics and Astronomy, University of Bologna, Bologna, Italy
| | - Mauro Murgia
- Instituto per lo Studio dei Materiali Nanostrutturati (ISMN), Centro Nazionale delle Ricerche (CNR), Via Gobetti 101, 40129, Bologna, Italy
| | - Erika Scavetta
- Department of Industrial Chemistry, University of Bologna, Bologna, Italy
| | - Roberto Amici
- Department of Biomedical and Neuromotor Sciences - Physiology, University of Bologna, Bologna, Italy
| | - Beatrice Fraboni
- Department of Physics and Astronomy, University of Bologna, Bologna, Italy
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26
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Advances in Penetrating Multichannel Microelectrodes Based on the Utah Array Platform. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1101:1-40. [PMID: 31729670 DOI: 10.1007/978-981-13-2050-7_1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The Utah electrode array (UEA) and its many derivatives have become a gold standard for high-channel count bi-directional neural interfaces, in particular in human subject applications. The chapter provides a brief overview of leading electrode concepts and the context in which the UEA has to be understood. It goes on to discuss the key advances and developments of the UEA platform in the past 15 years, as well as novel wireless and system integration technologies that will merge into future generations of fully integrated devices. Aspects covered include novel device architectures that allow scaling of channel count and density of electrode contacts, material improvements to substrate, electrode contacts, and encapsulation. Further subjects are adaptations of the UEA platform to support IR and optogenetic simulation as well as an improved understanding of failure modes and methods to test and accelerate degradation in vitro such as to better predict device failure and lifetime in vivo.
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27
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Hagen E, Næss S, Ness TV, Einevoll GT. Multimodal Modeling of Neural Network Activity: Computing LFP, ECoG, EEG, and MEG Signals With LFPy 2.0. Front Neuroinform 2018; 12:92. [PMID: 30618697 PMCID: PMC6305460 DOI: 10.3389/fninf.2018.00092] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Accepted: 11/21/2018] [Indexed: 11/13/2022] Open
Abstract
Recordings of extracellular electrical, and later also magnetic, brain signals have been the dominant technique for measuring brain activity for decades. The interpretation of such signals is however nontrivial, as the measured signals result from both local and distant neuronal activity. In volume-conductor theory the extracellular potentials can be calculated from a distance-weighted sum of contributions from transmembrane currents of neurons. Given the same transmembrane currents, the contributions to the magnetic field recorded both inside and outside the brain can also be computed. This allows for the development of computational tools implementing forward models grounded in the biophysics underlying electrical and magnetic measurement modalities. LFPy (LFPy.readthedocs.io) incorporated a well-established scheme for predicting extracellular potentials of individual neurons with arbitrary levels of biological detail. It relies on NEURON (neuron.yale.edu) to compute transmembrane currents of multicompartment neurons which is then used in combination with an electrostatic forward model. Its functionality is now extended to allow for modeling of networks of multicompartment neurons with concurrent calculations of extracellular potentials and current dipole moments. The current dipole moments are then, in combination with suitable volume-conductor head models, used to compute non-invasive measures of neuronal activity, like scalp potentials (electroencephalographic recordings; EEG) and magnetic fields outside the head (magnetoencephalographic recordings; MEG). One such built-in head model is the four-sphere head model incorporating the different electric conductivities of brain, cerebrospinal fluid, skull and scalp. We demonstrate the new functionality of the software by constructing a network of biophysically detailed multicompartment neuron models from the Neocortical Microcircuit Collaboration (NMC) Portal (bbp.epfl.ch/nmc-portal) with corresponding statistics of connections and synapses, and compute in vivo-like extracellular potentials (local field potentials, LFP; electrocorticographical signals, ECoG) and corresponding current dipole moments. From the current dipole moments we estimate corresponding EEG and MEG signals using the four-sphere head model. We also show strong scaling performance of LFPy with different numbers of message-passing interface (MPI) processes, and for different network sizes with different density of connections. The open-source software LFPy is equally suitable for execution on laptops and in parallel on high-performance computing (HPC) facilities and is publicly available on GitHub.com.
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Affiliation(s)
- Espen Hagen
- Department of Physics, University of Oslo, Oslo, Norway.,Faculty of Science and Technology, Norwegian University of Life Sciences, Ås, Norway
| | - Solveig Næss
- Department of Informatics, University of Oslo, Oslo, Norway
| | - Torbjørn V Ness
- Faculty of Science and Technology, Norwegian University of Life Sciences, Ås, Norway
| | - Gaute T Einevoll
- Department of Physics, University of Oslo, Oslo, Norway.,Faculty of Science and Technology, Norwegian University of Life Sciences, Ås, Norway
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28
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Sartori AF, Orlando S, Bellucci A, Trucchi DM, Abrahami S, Boehme T, Hantschel T, Vandervorst W, Buijnsters JG. Laser-Induced Periodic Surface Structures (LIPSS) on Heavily Boron-Doped Diamond for Electrode Applications. ACS APPLIED MATERIALS & INTERFACES 2018; 10:43236-43251. [PMID: 30431259 PMCID: PMC6326536 DOI: 10.1021/acsami.8b15951] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Diamond is known as a promising electrode material in the fields of cell stimulation, energy storage (e.g., supercapacitors), (bio)sensing, catalysis, etc. However, engineering its surface and electrochemical properties often requires costly and complex procedures with addition of foreign material (e.g., carbon nanotube or polymer) scaffolds or cleanroom processing. In this work, we demonstrate a novel approach using laser-induced periodic surface structuring (LIPSS) as a scalable, versatile, and cost-effective technique to nanostructure the surface and tune the electrochemical properties of boron-doped diamond (BDD). We study the effect of LIPSS on heavily doped BDD and investigate its application as electrodes for cell stimulation and energy storage. We show that quasi-periodic ripple structures formed on diamond electrodes laser-textured with a laser accumulated fluence of 0.325 kJ/cm2 (800 nm wavelength) displayed a much higher double-layer capacitance of 660 μF/cm2 than the as-grown BDD (20 μF/cm2) and that an increased charge-storage capacity of 1.6 mC/cm2 (>6-fold increase after laser texturing) and a low impedance of 2.74 Ω cm2 turn out to be appreciable properties for cell stimulation. Additional morphological and structural characterization revealed that ripple formation on heavily boron-doped diamond (2.8 atom % [B]) occurs at much lower accumulated fluences than the 2 kJ/cm2 typically reported for lower doping levels and that the process involves stronger graphitization of the BDD surface. Finally, we show that the exposed interface between sp2 and sp3 carbon layers (i.e. the laser-ablated diamond surface) revealed faster kinetics than the untreated BDD in both ferrocyanide and RuHex mediators, which can be used for electrochemical (bio)sensing. Overall, our work demonstrates that LIPSS is a powerful single-step tool for the fabrication of surface-engineered diamond electrodes with tunable material, electrochemical, and charge-storage properties.
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Affiliation(s)
- André F. Sartori
- Department of Precision
and Microsystems Engineering, Research Group of Micro and Nano Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft, The Netherlands
- E-mail: . Tel.: +31 (0)15 27 86089 (A.F.S.)
| | - Stefano Orlando
- Istituto di Struttura della Materia (ISM), Unit of Montelibretti, Consiglio Nazionale delle Ricerche (CNR), Research
Area of Rome 1, Via Salaria
km 29.300, 00015 Monterotondo Scalo, Roma, Italy
| | - Alessandro Bellucci
- Istituto di Struttura della Materia (ISM), Unit of Montelibretti, Consiglio Nazionale delle Ricerche (CNR), Research
Area of Rome 1, Via Salaria
km 29.300, 00015 Monterotondo Scalo, Roma, Italy
| | - Daniele M. Trucchi
- Istituto di Struttura della Materia (ISM), Unit of Montelibretti, Consiglio Nazionale delle Ricerche (CNR), Research
Area of Rome 1, Via Salaria
km 29.300, 00015 Monterotondo Scalo, Roma, Italy
| | - Shoshan Abrahami
- Department
of Materials and Chemistry, Research Group Electrochemical and Surface
Engineering (SURF), Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
| | - Thijs Boehme
- Imec, Kapeldreef 75, B-3001 Leuven, Belgium
- IKS-Department of Physics, KU Leuven, Celestijnenlaan
200D, B-3001 Leuven, Belgium
| | | | - Wilfried Vandervorst
- Imec, Kapeldreef 75, B-3001 Leuven, Belgium
- IKS-Department of Physics, KU Leuven, Celestijnenlaan
200D, B-3001 Leuven, Belgium
| | - Josephus G. Buijnsters
- Department of Precision
and Microsystems Engineering, Research Group of Micro and Nano Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft, The Netherlands
- E-mail: . Tel.: +31 (0)15 27 85396 (J.G.B)
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29
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Suarez-Perez A, Gabriel G, Rebollo B, Illa X, Guimerà-Brunet A, Hernández-Ferrer J, Martínez MT, Villa R, Sanchez-Vives MV. Quantification of Signal-to-Noise Ratio in Cerebral Cortex Recordings Using Flexible MEAs With Co-localized Platinum Black, Carbon Nanotubes, and Gold Electrodes. Front Neurosci 2018; 12:862. [PMID: 30555290 PMCID: PMC6282047 DOI: 10.3389/fnins.2018.00862] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 11/05/2018] [Indexed: 11/25/2022] Open
Abstract
Developing new standardized tools to characterize brain recording devices is critical to evaluate neural probes and for translation to clinical use. The signal-to-noise ratio (SNR) measurement is the gold standard for quantifying the performance of brain recording devices. Given the drawbacks with the SNR measure, our first objective was to devise a new method to calculate the SNR of neural signals to distinguish signal from noise. Our second objective was to apply this new SNR method to evaluate electrodes of three different materials (platinum black, Pt; carbon nanotubes, CNTs; and gold, Au) co-localized in tritrodes to record from the same cortical area using specifically designed multielectrode arrays. Hence, we devised an approach to calculate SNR at different frequencies based on the features of cortical slow oscillations (SO). Since SO consist in the alternation of silent periods (Down states) and active periods (Up states) of neuronal activity, we used these as noise and signal, respectively. The spectral SNR was computed as the power spectral density (PSD) of Up states (signal) divided by the PSD of Down states (noise). We found that Pt and CNTs electrodes have better recording performance than Au electrodes for the explored frequency range (5–1500 Hz). Together with two proposed SNR estimators for the lower and upper frequency limits, these results substantiate our SNR calculation at different frequency bands. Our results provide a new validated SNR measure that provides rich information of the performance of recording devices at different brain activity frequency bands (<1500 Hz).
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Affiliation(s)
- Alex Suarez-Perez
- Systems Neuroscience, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Gemma Gabriel
- Instituto de Microelectrónica de Barcelona, Centro Nacional de Microelectrónica, Consejo Superior de Investigaciones Científicas, Barcelona, Spain.,Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina, Madrid, Spain
| | - Beatriz Rebollo
- Systems Neuroscience, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Xavi Illa
- Instituto de Microelectrónica de Barcelona, Centro Nacional de Microelectrónica, Consejo Superior de Investigaciones Científicas, Barcelona, Spain.,Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina, Madrid, Spain
| | - Anton Guimerà-Brunet
- Instituto de Microelectrónica de Barcelona, Centro Nacional de Microelectrónica, Consejo Superior de Investigaciones Científicas, Barcelona, Spain.,Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina, Madrid, Spain
| | | | - Maria Teresa Martínez
- Instituto de Carboquímica, Consejo Superior de Investigaciones Científicas, Zaragoza, Spain
| | - Rosa Villa
- Instituto de Microelectrónica de Barcelona, Centro Nacional de Microelectrónica, Consejo Superior de Investigaciones Científicas, Barcelona, Spain.,Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina, Madrid, Spain
| | - Maria V Sanchez-Vives
- Systems Neuroscience, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.,ICREA, Barcelona, Spain
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30
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Jia Y, Khan W, Lee B, Fan B, Madi F, Weber A, Li W, Ghovanloo M. Wireless opto-electro neural interface for experiments with small freely behaving animals. J Neural Eng 2018; 15:046032. [PMID: 29799437 PMCID: PMC6091646 DOI: 10.1088/1741-2552/aac810] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
OBJECTIVE We have developed a wireless opto-electro interface (WOENI) device, which combines electrocorticogram (ECoG) recording and optical stimulation for bi-directional neuromodulation on small, freely behaving animals, such as rodents. APPROACH The device is comprised of two components, a detachable headstage and an implantable polyimide-based substrate. The headstage establishes a bluetooth low energy (BLE) bi-directional data communication with an external custom-designed USB dongle for receiving user commands and optogenetic stimulation patterns, and sending digitalized ECoG data. MAIN RESULTS The functionality and stability of the device were evaluated in vivo on freely behaving rats. When the animal received optical stimulation on the primary visual cortex (V1) and visual stimulation via eyes, spontaneous changes in ECoG signals were recorded from both left and right V1 during four consecutive experiments with 7 d intervals over a time span of 21 d following device implantation. Immunostained tissue analyses showed results consistent with ECoG analyses, validating the efficacy of optical stimulation to upregulate the activity of cortical neurons expressing ChR2. SIGNIFICANCE The proposed WOENI device is potentially a versatile tool in the studies that involve long-term optogenetic neuromodulation.
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Affiliation(s)
- Yaoyao Jia
- GT-Bionics Lab, School of Electrical and Computer Engineering, Georgia Tech, Atlanta, GA, United States of America
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31
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Mechanically tunable conductive interpenetrating network hydrogels that mimic the elastic moduli of biological tissue. Nat Commun 2018; 9:2740. [PMID: 30013027 PMCID: PMC6048132 DOI: 10.1038/s41467-018-05222-4] [Citation(s) in RCA: 218] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 06/21/2018] [Indexed: 12/27/2022] Open
Abstract
Conductive and stretchable materials that match the elastic moduli of biological tissue (0.5–500 kPa) are desired for enhanced interfacial and mechanical stability. Compared with inorganic and dry polymeric conductors, hydrogels made with conducting polymers are promising soft electrode materials due to their high water content. Nevertheless, most conducting polymer-based hydrogels sacrifice electronic performance to obtain useful mechanical properties. Here we report a method that overcomes this limitation using two interpenetrating hydrogel networks, one of which is formed by the gelation of the conducting polymer PEDOT:PSS. Due to the connectivity of the PEDOT:PSS network, conductivities up to 23 S m−1 are achieved, a record for stretchable PEDOT:PSS-based hydrogels. Meanwhile, the low concentration of PEDOT:PSS enables orthogonal control over the composite mechanical properties using a secondary polymer network. We demonstrate tunability of the elastic modulus over three biologically relevant orders of magnitude without compromising stretchability ( > 100%) or conductivity ( > 10 S m−1). Conductive and stretchable materials that match the elastic moduli of biological tissue are desired for enhanced interfacial and mechanical stability. Here the authors show a method for fabricating highly conductive hydrogels comprising two interpenetrating networks.
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32
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Prox J, Smith T, Holl C, Chehade N, Guo L. Integrated biocircuits: engineering functional multicellular circuits and devices. J Neural Eng 2018; 15:023001. [DOI: 10.1088/1741-2552/aaa906] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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33
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Affiliation(s)
- Eduardo Fernández
- Bioengineering Institute; Miguel Hernández University of Elche and CIBER BBN; Elche 03202 Spain
| | - Pablo Botella
- Instituto de Tecnología Química; Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas; Valencia 46022 Spain
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34
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Tia B, Takemi M, Kosugi A, Castagnola E, Ansaldo A, Nakamura T, Ricci D, Ushiba J, Fadiga L, Iriki A. Cortical control of object-specific grasp relies on adjustments of both activity and effective connectivity: a common marmoset study. J Physiol 2017; 595:7203-7221. [PMID: 28791721 PMCID: PMC5709338 DOI: 10.1113/jp274629] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2017] [Accepted: 07/31/2017] [Indexed: 01/22/2023] Open
Abstract
Key points The cortical mechanisms of grasping have been extensively studied in macaques and humans; here, we investigated whether common marmosets could rely on similar mechanisms despite strong differences in hand morphology and grip diversity. We recorded electrocorticographic activity over the sensorimotor cortex of two common marmosets during the execution of different grip types, which allowed us to study cortical activity (power spectrum) and physiologically inferred connectivity (phase‐slope index). Analyses were performed in beta (16–35 Hz) and gamma (75–100 Hz) frequency bands and our results showed that beta power varied depending on grip type, whereas gamma power displayed clear epoch‐related modulation. Strength and direction of inter‐area connectivity varied depending on grip type and epoch. These findings suggest that fundamental control mechanisms are conserved across primates and, in future research, marmosets could represent an adequate model to investigate primate brain mechanisms.
Abstract The cortical mechanisms of grasping have been extensively studied in macaques and humans. Here, we investigated whether common marmosets could rely on similar mechanisms despite striking differences in manual dexterity. Two common marmosets were trained to grasp‐and‐pull three objects eliciting different hand configurations: whole‐hand, finger and scissor grips. The animals were then chronically implanted with 64‐channel electrocorticogram arrays positioned over the left premotor, primary motor and somatosensory cortex. Power spectra, reflecting predominantly cortical activity, and phase‐slope index, reflecting the direction of information flux, were studied in beta (16–35 Hz) and gamma (75–100 Hz) bands. Differences related to grip type, epoch (reach, grasp) and cortical area were statistically assessed. Results showed that whole‐hand and scissor grips triggered stronger beta desynchronization than finger grip. Task epochs clearly modulated gamma power, especially for finger and scissor grips. Considering effective connectivity, finger and scissor grips evoked stronger outflow from primary motor to premotor cortex, whereas whole‐hand grip displayed the opposite pattern. These findings suggest that fundamental control mechanisms, relying on adjustments of cortical activity and connectivity, are conserved across primates. Consistently, marmosets could represent a good model to investigate primate brain mechanisms. The cortical mechanisms of grasping have been extensively studied in macaques and humans; here, we investigated whether common marmosets could rely on similar mechanisms despite strong differences in hand morphology and grip diversity. We recorded electrocorticographic activity over the sensorimotor cortex of two common marmosets during the execution of different grip types, which allowed us to study cortical activity (power spectrum) and physiologically inferred connectivity (phase‐slope index). Analyses were performed in beta (16–35 Hz) and gamma (75–100 Hz) frequency bands and our results showed that beta power varied depending on grip type, whereas gamma power displayed clear epoch‐related modulation. Strength and direction of inter‐area connectivity varied depending on grip type and epoch. These findings suggest that fundamental control mechanisms are conserved across primates and, in future research, marmosets could represent an adequate model to investigate primate brain mechanisms.
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Affiliation(s)
- Banty Tia
- Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Saitama, Japan.,Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di Tecnologia, Ferrara, Italy
| | - Mitsuaki Takemi
- Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Saitama, Japan.,Graduate School of Science and Technology, Keio University, Kanagawa, Japan.,Danish Research Centre for Magnetic Resonance, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark
| | - Akito Kosugi
- Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Saitama, Japan.,Graduate School of Science and Technology, Keio University, Kanagawa, Japan
| | - Elisa Castagnola
- Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di Tecnologia, Ferrara, Italy
| | - Alberto Ansaldo
- Graphene Labs, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Takafumi Nakamura
- Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Saitama, Japan.,Graduate School of Science and Technology, Keio University, Kanagawa, Japan
| | - Davide Ricci
- Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di Tecnologia, Ferrara, Italy
| | - Junichi Ushiba
- Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Kanagawa, Japan.,Keio Institute of Pure and Applied Sciences (KiPAS), Keio University, Kanagawa, Japan
| | - Luciano Fadiga
- Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di Tecnologia, Ferrara, Italy
| | - Atsushi Iriki
- Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Saitama, Japan
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Jeong J, Chou N, Kim S. Long-term characterization of neural electrodes based on parylene-caulked polydimethylsiloxane substrate. Biomed Microdevices 2017; 18:42. [PMID: 27165102 DOI: 10.1007/s10544-016-0065-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
This study investigates the mechanical and long-term electrical properties of parylene-caulked polydimethylsiloxane (PDMS) as a substrate for implantable electrodes. The parylene-caulked PDMS is a structure where particles of parylene fill the porous surface of PDMS. This material is expected to have low water absorption and desirable mechanical properties such as flexibility and elasticity that are beneficial in many biomedical applications. To evaluate the mechanical property and electrical stability of parylene-caulked PDMS for potential in-vivo uses, tensile tests were conducted firstly, which results showed that the mechanical strength of parylene-caulked PDMS was comparable to that of native PDMS. Next, surface electrodes based on parylene-caulked PDMS were fabricated and their impedance was measured in phosphate-buffered saline (PBS) solution at 36.5 °C over seven months. The electrodes based on parylene-caulked PDMS exhibited the improved stability in impedance over time than native PDMS. Thus, with improved electrical stability in wet environment and preserved mechanical properties of PDMS, the electrodes based on parylene-caulked PDMS are expected to be suitable for long-term in-vivo applications.
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Affiliation(s)
- Jinmo Jeong
- School of Mechatronics, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
| | - Namsun Chou
- School of Mechatronics, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
| | - Sohee Kim
- Department of Robotics Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Republic of Korea.
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Castagnola E, Maggiolini E, Ceseracciu L, Ciarpella F, Zucchini E, De Faveri S, Fadiga L, Ricci D. pHEMA Encapsulated PEDOT-PSS-CNT Microsphere Microelectrodes for Recording Single Unit Activity in the Brain. Front Neurosci 2016; 10:151. [PMID: 27147944 PMCID: PMC4834343 DOI: 10.3389/fnins.2016.00151] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 03/21/2016] [Indexed: 12/18/2022] Open
Abstract
The long-term reliability of neural interfaces and stability of high-quality recordings are still unsolved issues in neuroscience research. High surface area PEDOT-PSS-CNT composites are able to greatly improve the performance of recording and stimulation for traditional intracortical metal microelectrodes by decreasing their impedance and increasing their charge transfer capability. This enhancement significantly reduces the size of the implantable device though preserving excellent electrical performances. On the other hand, the presence of nanomaterials often rises concerns regarding possible health hazards, especially when considering a clinical application of the devices. For this reason, we decided to explore the problem from a new perspective by designing and testing an innovative device based on nanostructured microspheres grown on a thin tether, integrating PEDOT-PSS-CNT nanocomposites with a soft synthetic permanent biocompatible hydrogel. The pHEMA hydrogel preserves the electrochemical performance and high quality recording ability of PEDOT-PSS-CNT coated devices, reduces the mechanical mismatch between soft brain tissue and stiff devices and also avoids direct contact between the neural tissue and the nanocomposite, by acting as a biocompatible protective barrier against potential nanomaterial detachment. Moreover, the spherical shape of the electrode together with the surface area increase provided by the nanocomposite deposited on it, maximize the electrical contact and may improve recording stability over time. These results have a good potential to contribute to fulfill the grand challenge of obtaining stable neural interfaces for long-term applications.
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Affiliation(s)
- Elisa Castagnola
- Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di TecnologiaFerrara, Italy
| | - Emma Maggiolini
- Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di TecnologiaFerrara, Italy
| | - Luca Ceseracciu
- Department of Smart Materials, Istituto Italiano di TecnologiaGenova, Italy
| | | | - Elena Zucchini
- Section of Human Physiology, University of FerraraFerrara, Italy
| | - Sara De Faveri
- Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di TecnologiaFerrara, Italy
| | - Luciano Fadiga
- Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di TecnologiaFerrara, Italy
- Section of Human Physiology, University of FerraraFerrara, Italy
| | - Davide Ricci
- Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di TecnologiaFerrara, Italy
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Lee JH, Kim H, Kim JH, Lee SH. Soft implantable microelectrodes for future medicine: prosthetics, neural signal recording and neuromodulation. LAB ON A CHIP 2016; 16:959-76. [PMID: 26891410 DOI: 10.1039/c5lc00842e] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Implantable devices have provided various potential diagnostic options and therapeutic methods in diverse medical fields. A variety of hard-material-based implantable electrodes have been developed. However, several limitations for their chronic implantation remain, including mechanical mismatches at the interface between the electrode and the soft tissue, and biocompatibility. Soft-material-based implantable devices are suitable candidates for complementing the limitations of hard electrodes. Advances in microtechnology and materials science have largely solved many challenges, such as optimization of shape, minimization of infection, enhancement of biocompatibility and integration with components for diverse functions. Significant strides have also been made in mechanical matching of electrodes to soft tissue. In this review, we provide an overview of recent advances in soft-material-based implantable electrodes for medical applications, categorized according to their implantation site and material composition. We then review specific applications in three categories: neuroprosthetics, neural signal recording, and neuromodulation. Finally, we describe various strategies for the future development and application of implantable, soft-material-based devices.
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Affiliation(s)
- Joong Hoon Lee
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-701, Republic of Korea
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Park AH, Lee SH, Lee C, Kim J, Lee HE, Paik SB, Lee KJ, Kim D. Optogenetic Mapping of Functional Connectivity in Freely Moving Mice via Insertable Wrapping Electrode Array Beneath the Skull. ACS NANO 2016; 10:2791-802. [PMID: 26735496 DOI: 10.1021/acsnano.5b07889] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Spatiotemporal mapping of neural interactions through electrocorticography (ECoG) is the key to understanding brain functions and disorders. For the entire brain cortical areas, this approach has been challenging, especially in freely moving states, owing to the need for extensive craniotomy. Here, we introduce a flexible microelectrode array system, termed iWEBS, which can be inserted through a small cranial slit and stably wrap onto the curved cortical surface. Using iWEBS, we measured dynamic changes of signals across major cortical domains, namely, somatosensory, motor, visual and retrosplenial areas, in freely moving mice. iWEBS robustly displayed somatosensory evoked potentials (SEPs) in corresponding cortical areas to specific somatosensory stimuli. We also used iWEBS for mapping functional interactions between cortical areas in the propagation of spike-and-wave discharges (SWDs), the neurological marker of absence seizures, triggered by optogenetic inhibition of a specific thalamic nucleus. This demonstrates that iWEBS represents a significant improvement over conventional ECoG recording methodologies and, therefore, is a competitive recording system for mapping wide-range brain connectivity under various behavioral conditions.
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Affiliation(s)
- Ah Hyung Park
- Department of Biological Sciences, ‡Department of Materials Science and Engineering, and §Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST) , 291, Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Seung Hyun Lee
- Department of Biological Sciences, ‡Department of Materials Science and Engineering, and §Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST) , 291, Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Changju Lee
- Department of Biological Sciences, ‡Department of Materials Science and Engineering, and §Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST) , 291, Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Jeongjin Kim
- Department of Biological Sciences, ‡Department of Materials Science and Engineering, and §Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST) , 291, Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Han Eol Lee
- Department of Biological Sciences, ‡Department of Materials Science and Engineering, and §Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST) , 291, Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Se-Bum Paik
- Department of Biological Sciences, ‡Department of Materials Science and Engineering, and §Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST) , 291, Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Keon Jae Lee
- Department of Biological Sciences, ‡Department of Materials Science and Engineering, and §Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST) , 291, Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Daesoo Kim
- Department of Biological Sciences, ‡Department of Materials Science and Engineering, and §Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST) , 291, Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
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Adewole DO, Serruya MD, Harris JP, Burrell JC, Petrov D, Chen HI, Wolf JA, Cullen DK. The Evolution of Neuroprosthetic Interfaces. Crit Rev Biomed Eng 2016; 44:123-52. [PMID: 27652455 PMCID: PMC5541680 DOI: 10.1615/critrevbiomedeng.2016017198] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The ideal neuroprosthetic interface permits high-quality neural recording and stimulation of the nervous system while reliably providing clinical benefits over chronic periods. Although current technologies have made notable strides in this direction, significant improvements must be made to better achieve these design goals and satisfy clinical needs. This article provides an overview of the state of neuroprosthetic interfaces, starting with the design and placement of these interfaces before exploring the stimulation and recording platforms yielded from contemporary research. Finally, we outline emerging research trends in an effort to explore the potential next generation of neuroprosthetic interfaces.
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Affiliation(s)
- Dayo O. Adewole
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, USA
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, USA
- Penn Center for Neuroengineering and Therapeutics, University of Pennsylvania, Philadelphia, PA, USA
| | - Mijail D. Serruya
- Department of Neurology, Jefferson University, Philadelphia, PA, USA
| | - James P. Harris
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, USA
| | - Justin C. Burrell
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, USA
| | - Dmitriy Petrov
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, USA
| | - H. Isaac Chen
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, USA
- Penn Center for Neuroengineering and Therapeutics, University of Pennsylvania, Philadelphia, PA, USA
| | - John A. Wolf
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, USA
| | - D. Kacy Cullen
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, USA
- Penn Center for Neuroengineering and Therapeutics, University of Pennsylvania, Philadelphia, PA, USA
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Jeong JW, Shin G, Park SI, Yu KJ, Xu L, Rogers JA. Soft materials in neuroengineering for hard problems in neuroscience. Neuron 2015; 86:175-86. [PMID: 25856493 DOI: 10.1016/j.neuron.2014.12.035] [Citation(s) in RCA: 159] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We describe recent advances in soft electronic interface technologies for neuroscience research. Here, low modulus materials and/or compliant mechanical structures enable modes of soft, conformal integration and minimally invasive operation that would be difficult or impossible to achieve using conventional approaches. We begin by summarizing progress in electrodes and associated electronics for signal amplification and multiplexed readout. Examples in large-area, surface conformal electrode arrays and flexible, multifunctional depth-penetrating probes illustrate the power of these concepts. A concluding section highlights areas of opportunity in the further development and application of these technologies.
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Affiliation(s)
- Jae-Woong Jeong
- Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Gunchul Shin
- Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Sung Il Park
- Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Ki Jun Yu
- Department of Electrical and Computer Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Lizhi Xu
- Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - John A Rogers
- Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Department of Electrical and Computer Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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Hofmann UG, Krüger J. The chronic challenge-new vistas on long-term multisite contacts to the central nervous system. FRONTIERS IN NEUROENGINEERING 2015; 8:3. [PMID: 25852537 PMCID: PMC4364247 DOI: 10.3389/fneng.2015.00003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 02/27/2015] [Indexed: 01/16/2023]
Affiliation(s)
- Ulrich G Hofmann
- Section for Neuroelectronic Systems, Clinic for Neurosurgery, Albert-Ludwigs-University Freiburg Freiburg, Germany ; Cluster of Excellence "BrainLinks-BrainTools" EXC 1086 Freiburg, Germany
| | - Jürgen Krüger
- AG Hirnforschung, Universität Freiburg Freiburg, Germany
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Ersen A, Elkabes S, Freedman DS, Sahin M. Chronic tissue response to untethered microelectrode implants in the rat brain and spinal cord. J Neural Eng 2015; 12:016019. [PMID: 25605679 DOI: 10.1088/1741-2560/12/1/016019] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVE Microelectrodes implanted in the central nervous system (CNS) often fail in long term implants due to the immunological tissue response caused by tethering forces of the connecting wires. In addition to the tethering effect, there is a mechanical stress that occurs at the device-tissue interface simply because the microelectrode is a rigid body floating in soft tissue and it cannot reshape itself to comply with changes in the surrounding tissue. In the current study we evaluated the scar tissue formation to tetherless devices with two significantly different geometries in the rat brain and spinal cord in order to investigate the effects of device geometry. APPROACH One of the implant geometries resembled the wireless, floating microstimulators that we are currently developing in our laboratory and the other was a (shank only) Michigan probe for comparison. Both electrodes were implanted into either the cervical spinal cord or the motor cortices, one on each side. MAIN RESULTS The most pronounced astroglial and microglial reactions occurred within 20 μm from the device and decreased sharply at larger distances. Both cell types displayed the morphology of non-activated cells past the 100 μm perimeter. Even though the aspect ratios of the implants were different, the astroglial and microglial responses to both microelectrode types were very mild in the brain, stronger and yet limited in the spinal cord. SIGNIFICANCE These observations confirm previous reports and further suggest that tethering may be responsible for most of the tissue response in chronic implants and that the electrode size has a smaller contribution with floating electrodes. The electrode size may be playing primarily an amplifying role to the tethering forces in the brain whereas the size itself may induce chronic response in the spinal cord where the movement of surrounding tissues is more significant.
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Affiliation(s)
- Ali Ersen
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, USA
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