DGIST Scholar: Flexible and Transparent Ultrathin Gold Microelectrode Array for Electro-Optical Neural Interface

Department of Electrical Engineering and Computer Science Theses Master

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Flexible and Transparent Ultrathin Gold Microelectrode Array for Electro-Optical Neural Interface

Title: Flexible and Transparent Ultrathin Gold Microelectrode Array for Electro-Optical Neural Interface

Alternative Title: 전기광학형 신경 인터페이스를 위한 플렉서블 투명 얇은 금 박막 미세전극 어레이

Author(s): Woongki Hong

DGIST Authors: Woongki Hong ; Hongki Kang ; Hyuk-Jun Kwon

Advisor: 강홍기

Co-Advisor(s): Hyuk-Jun Kwon

Issued Date: 2021

Awarded Date: 2021/02

Type: Thesis

Subject: Flexible and Transparent electronics, Ultrathin Metal Nanofilm, Microelectrode Array, Electrophysiological Recording, Electro-Optical Neural Interface, 플렉서블 투명 전극, 얇은 금 박막 나노필름, 미세전극 어레이, 전기생리학적 레코딩, 전기 광학적 인터페이스

Table Of Contents: 1. INTRODUCTION 1
1.1. Motivation 1
1.2. Neural Signal Interface 1
1.2.1. Invasive Neural Interface 2
1.2.2. Non-Invasive Neural Interface 2
1.3. Electrochemical Measurement 3
1.3.1. Electrochemical Impedance Spectroscopy 3
1.3.2. Two Electrode System 4
1.3.3. Double Layer Capacitance 5
1.3.4. Nyquist Plot 6
1.4. Flexible and Transparent Electronics 7
1.4.1. Conventional Flexible and Transparent Electrode 7
1.4.2. Ultrathin Metal Nanofilm 8
1.4.3. Layer-by-Layer coated Polyelectrolytes 9
1.4.4. Flexible Substrates 10
2. EXPERIMENTAL METHOD 11
2.1. Device Structure and Fabrication 11
2.1.1. Layer-by-Layer Polyelectrolytes Characterization 12
2.1.2. Ultrathin Gold Microelectrode Array 12
2.1.3. Bulk Gold Microelectrode Array 13
2.2. Electro-Optical Characterization 14
2.3. Mechanical Flexibility Test 15
2.4. Electrochemical Measurement 15
2.4.1. Modeling of Electrochemical Measurement 15
2.4.2. Experimental Setup 16
2.5. Biocompatibility Test 17
2.6. Simulation modeling of in vivo photothermal stimulation using thermo-plasmonic optical fiber 18
3. RESULT & DISCUSSION 20
3.1. Material Characteristics of Ultrathin Gold Microelectrode Array 20
3.2. Electrical and Optical Characteristics of Ultrathin Gold Microelectrodes 23
3.2.1. Optical Characteristics of Ultrathin Gold Electrode 23
3.2.2. Electrical Characteristics of Ultrathin Gold Microelectrode on Flexible Substrate 24
3.2.3. Mechanical Flexibility on Ultrathin Gold Microelectrodes 29
3.3. Electrochemical Impedance Spectroscopy (EIS) 29
3.4. Electrophysiological Measurements 34
3.4.1. Biocompatibility Test 34
3.4.2. RMS Noise 35
3.5. COMSOL Simulation 36
4. CONCLUSION 38
5. APPREDIX 39
A1. MATLAB Source Code for Power Spectrum Density (PSD) 39
A2. Electrochemical Impedance Measurement 40
A3. EIS spectrum Analysis 41
A4. Electrophysiological Measurements 42
A5. COMSOL Simulation Software 43