Hierarchically Structured Flexible Electrode on Polyimide for Highly Sensitive and Reliable Biosignal Acquisition

Jinpyeo Jeung,Yunsik Kim,Yoonyoung Chung,Inyeol Yun,Suwon Seong

doi:10.1109/access.2022.3152533

Abstract

Numerous wearable biomedical devices are developed for the continuous monitoring of personal health or condition. Biosignals acquisition with high sensitivity is important for designing wearable biomedical devices. A sensing electrode between the human body and wearable electronics significantly affects the sensitivity of the sensors. In this study, we fabricated hierarchically structured flexible electrodes on polyimide substrate (HSFE-PI) using micro-casting technique and gold nanoparticles electrodeposition. Polyimides provides robust and outstanding electrical characteristics, and the reliability of HSFE-PI was verified with a cyclic bending test. The integration of hierarchical structures significantly increased the surface area of the electrode by 2.06 times. We applied the HSFE-PI for electromyogram (EMG) and glucose sensing applications and achieved high sensitivity enhancement in both applications. The signal-to-noise ratio (SNR) of measured EMG signals was increased by 2.48 times, and the sensitivity of the glucose detection was increased by 1.42 times compared to the planar counterpart.

Highlights

Wearable biomedical devices have received much attention to monitor individuals’ health condition continuously by measuring various biosignals, such as electrocardiogram (ECG), electromyogram (EMG), ion concentration, and blood glucose level, in real time [1,2,3,4,5,6]
A hierarchically structured flexible electrode is an optimal approach to significantly enhance the performance as the hierarchical structures enlarge the surface area, and the flexibility provides a conformal contact with the curvature of the skin
We demonstrated hierarchically structured flexible electrodes on polyimide substrate (HSFE-PI) and applied the electrode to the biosignals measurements (Figure 1)

Summary

Introduction

Wearable biomedical devices have received much attention to monitor individuals’ health condition continuously by measuring various biosignals, such as electrocardiogram (ECG), electromyogram (EMG), ion concentration, and blood glucose level, in real time [1,2,3,4,5,6]. Numerous previous studies on biosignal sensors report that the enlargement of contact area between the sensing electrodes and measured objects leads to a sensitivity enhancement [10,11,12]. The electrodeposition of nanoparticles on biopotential electrodes can increase the surface area, which improves the SNR in ECG and EMG measurements [7]. Hierarchical structures with micro-/nano- patterns improves the response time and sensitivity of electrochemical sensors through a large surface area [13,14,15,16,17]. A hierarchically structured flexible electrode is an optimal approach to significantly enhance the performance as the hierarchical structures enlarge the surface area, and the flexibility provides a conformal contact with the curvature of the skin. A direct deposition of conducting thin film on PDMS is VOLUME XX, 2017

Methods

Results

Conclusion