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Graphene-based Flexible Electrode Array with Nanowires and PEDOT Improving Neural Recordings

Title
Graphene-based Flexible Electrode Array with Nanowires and PEDOT Improving Neural Recordings
Translated Title
생체 신호 향상을 위한 나노와이어와 PEDOT 를 가지는 그래핀 기반의 유연한 뉴럴 전극
Authors
Ryu, Min Gyu
DGIST Authors
Ryu, Min Gyu; Jang, Jae Eun; Kim, Eun Kyoung
Advisor(s)
Jang, Jae Eun
Co-Advisor(s)
Kim, Eun Kyoung
Issue Date
2016
Available Date
2016-02-12
Degree Date
2016. 2
Type
Thesis
Keywords
Flexible Neural Electrode ArrayNanowiresPEDOTGraphene유연한 뉴럴 전극나노와이어그래핀
Abstract
Neural electrode array have been used to exchange electrical signals to neurons in the brain for decades. In this respect, the electrode-tissue interface plays an important role in neural recordings and stimulating. For small tissue damage and high selective of signals, smaller electrode size is required. However, there is a trade-off between electrode size and impedance of electrode-brain interface. As electrodes size is smaller, the impedance is sharply increased. Therefore, there is a major challenge to reducing electrode size while retaining electrode functionality. Furthermore, the mechanical mismatch between stiff electrodes and soft tissues causes reactive tissue responses. It is considered that reactive tissue response to electrode array should be minimized for long-term reliability to record neural signals. Flexible electrode design can be one of the solution without degradation under dynamic motion constantly. In this thesis, new probe designs are suggested and its electrical characteristics are studied. A Graphene-based flexible electrode array with nanowires and poly(3,4-ethylenedioxythiophene) PEDOT on the flexible substrate was fabricated. ZnO nanowires were used in a pillar structure, which expanded effective surface area to decrease dramatically electrode impedance. Furthermore, metallic nanowires were coated with PEDOT to enhance charge storage capacity and to record both electronic and ionic current. Graphene, which has high electrical conductivity and flexibility, is a good candidate as interconnects. The neural electrode array on flexible polyimide film enables to reduce mechanical mismatch for its long-term performance in comparison with electrodes fabricated on silicon. Due to a low impedance, a flexibility, and a low noise of the neural probe system, high signal-to-noise ratio (SNR) was achieved at in vitro and in vivo brain signal recordings. Therefore, the neural probe can be employed to various brain-electrical interface systems with high performances. ⓒ 2016 DGIST
Table Of Contents
Ⅰ. INTRODUCTION 1 -- 1.1 Motivation 1 -- 1.2 Neural Signal Transmission 2 -- 1.3 Neural Signals 3 -- 1.4 Reactive Tissue Responses 3 -- 1.4.1 Acute Response 4 -- 1.4.2 Chronic Response 4 -- 1.5 Electrochemical Interface of Electrode 5 -- 1.5.1 Electrochemical Impedance Spectroscopy 5 -- 1.5.2 Three Electrode System 5 -- 1.5.3 Cyclic Voltammetry 6 -- 1.5.4 Double Layer 7 -- 1.6 Nanowires 8 -- 1.6.1 Metallic Nanowires 9 -- 1.6.2 ZnO Nanowires 9 -- 1.7 Conducting Polymers 10 -- 1.7.1 poly(3,4-ethylenedioxythiophene) (PEDOT) 11 -- 1.8 Flexible Substrate 11 -- 1.9 Interconnect Lines 12 -- 1.9.1 Graphene 13 -- Ⅱ. EXPERIMENT DETAILS 14 -- 2.1 Materials & Design 14 -- 2.2 Fabrication of Neural Electrode Array 15 -- 2.2.1 Gold Electrode Array 15 -- 2.2.2 3D Contact Sites 16 -- 2.2.3 Gold/Graphene Multi-structure Interconnect Lines 18 -- 2.2.4 Encapsulation and Socket Bonding 19 -- 2.2.5 PEDOT Coating 20 -- Ⅲ. RESULTS AND DISCUSSION 23 -- 3.1 Characteristics of Electrode Array 23 -- 3.1.1 Electrochemical Characteristics of Electrode Array 23 -- 3.2 Characteristics of Flexible Substrates 29 -- 3.2.1 Electrical Characteristics of Flexible Substrates 29 -- 3.2.2 Electrochemical Properties of Flexible Substrates 31 -- 3.2.3 Mechanical Properties of Flexible Substrates 33 -- 3.3 Characteristics of Flexible Gold/Graphene Multi-layers Interconnect Lines 34 -- 3.3.1 Electrical Properties of Gold/Graphene Interconnect Lines 34 -- 3.3.2 Electrochemical Properties of Gold/Graphene Interconnect Lines 36 -- 3.4 In Vitro Signal Recordings 38 -- 3.5 In Vivo neural Signal Recordings 40 -- IV. CONCLUSION 43
URI
http://dgist.dcollection.net/jsp/common/DcLoOrgPer.jsp?sItemId=000002227728
http://hdl.handle.net/20.500.11750/1437
DOI
10.22677/thesis.2227728
Degree
Master
Department
Information and Communication Engineering
University
DGIST
Files:
Collection:
Information and Communication EngineeringThesesMaster


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