Stable epidermal electronic device with strain isolation induced by in situ Joule heating

Zihao Wang,Yangyong Zhao,Yixiang Shi,Tie Li,Simin Feng,Qifeng Lu,Yizhang Xia,Xianqing Yang,Fuqin Sun,Ting Zhang,Shuqi Wang

doi:10.1038/s41378-021-00282-x

Abstract

Epidermal electronics play increasingly important roles in human-machine interfaces. However, their efficient fabrication while maintaining device stability and reliability remains an unresolved challenge. Here, a facile in situ Joule heating method is proposed for fabricating stable epidermal electronics on a polyvinyl alcohol (PVA) substrate. Benefitting from the precise control of heating locations, the crystallization and enhanced rigidity of PVA are restricted to desired areas, leading to strain isolation of the active regions. As a result, the electronic device can be conformably attached to skin while showing negligible degradation in device performance during deformation. Based on this method, a flexible surface electromyography (sEMG) sensor with outstanding stability and highly comfortable wearability is demonstrated, showing high accuracy (91.83%) for human hand gesture recognition. These results imply that the fabrication method proposed in this research is a facile and reliable approach for the fabrication of epidermal electronics.

Highlights

Flexible electronics are considered the revolution in the electronics industry due to their potential applications in areas unreachable with rigid devices[1,2,3,4,5,6]
Previous reports indicated that the hydrogen bonds formed between polyvinyl alcohol (PVA) molecules could hinder crystallization of the membrane[30]; a decrease in the swelling rate of PVA is associated with an increase in PVA crystallinity[31]
The gradual decrease in the full width at half maximum (FWHM) of the diffraction peak at 19.8° with increasing annealing temperature is an indicator of the improvement in crystallinity

Summary

Introduction

Flexible electronics are considered the revolution in the electronics industry due to their potential applications in areas unreachable with rigid devices[1,2,3,4,5,6]. With an in situ Joule heating treatment, programmable changes in the crystallinity distribution can be achieved in the coplanar PVA substrate, resulting in a designed swelling rate and stiffness of the treated membrane. Properties of PVA membranes at different thermal treatment temperatures

Results

Conclusion