Wafer-Scale Fabrication and Assembly Method of Multichannel Microelectrode Arrays for ECoG Application

Cong Wang,Cheng-Peng Jiang,Yu-Chen Wei,Alok Kumar,Dan-Qing Zou,Rajendra Dhakal,Zhong-Liang Zhou,Ho-Kun Sung,Guo-Feng Yan,Jee-Hyun Choi

doi:10.3390/electronics10030316

Abstract

High density electrocorticography (ECoG)-based microelectrode arrays (MEAs) are fabricated to timely record the neural activities to provide the fundamental understanding in neuroscience and biomedical engineering. This paper aims to introduce a device-based concept and wafer-scale fabrication process for MEAs. Flexible and biocompatible polyimide is applied on MEAs to bear all possible stress and strain. Detailed fabrication key techniques, including surface treatment, polyimide stability measurement, evaporation process, and curing conditions, have been discussed thoroughly. Moreover, the fabricated polyimide-based MEAs are surface-mounted on well-packaged printed circuit boards (PCBs) via a slot-type connector without any additional wire bonding to make the signal recording process easier. An absence seizure was recorded during the in vivo test, which shows the availability of signal recording based on the presented MEAs. The proposed MEAs could be remained at the skull, while the connector and PCBs can be disassembled apart. Therefore, the testing sample will get less suffering. To verify the robustness of the fabricated MEAs, the impedance properties were characterized using electrochemical impedance spectroscopy. The measured results indicate an average impedance of 12.3 ± 0.675 kΩ at 1 kHz. In total, 10 groups of MEAs were sample tested, and over 90% of the total 60 channels per 1-MEAs operated efficiently.

Highlights

Electrical activity recording of neural cell networks can provide wealthy information concerning the physiology, as well as physiological degeneration that may cause diseases, such as Parkinson’s or Alzheimer’s [1,2]
The current research is focused on the fabrication of Microelectrode arrays (MEAs) with advanced micro-fabrication techniques to lower down the production cost and achieve a high yield
MEAs was comprised of a signal recording system, bibulous paper, assembled of the proposed MEAs was comprised of a signal recording system, bibulous paper, asMEAs asMEAs working electrodes, phosphate-buffered saline saline (PBS) solution, and a counter sembled as working electrodes, and aelectrode

Summary

Introduction

Electrical activity recording of neural cell networks can provide wealthy information concerning the physiology, as well as physiological degeneration that may cause diseases, such as Parkinson’s or Alzheimer’s [1,2]. The amplitude signals are larger and the higher-frequency patterns have greater resolution at the intracerebral local field potential and ECoG sites compared to scalp electroencephalogram (EEG) sites [4]. This method provides an advanced understanding of the functioning of brain activity. Flexibility and biocompatibility are the primary concern related to the practical implementation of MEAs for recording in vivo data from the subject on a long term basis [5] These conditions allow the MEAs to be placed directly on the skull to interface with the neural system. The large wafer-scale micro-fabrication can greatly reduce the manufacturing cost due to the possibility of mass production [19]

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Discussion

Conclusion