A biodegradable, highly sensitive and multifunctional mechanical sensor based on rGO-silk fibroin hydrogel for human motion detection and gesture recognition

Abstract

Hydrogel based flexible sensors have attracted tremendous attention in the fields of artificial skin, motion detection and health management due to their excellent characteristics such as portability and wearability. Herein, a flexible, conductive, and biodegradable hydrogel is prepared by proportionally mixing graphene oxide and silk fibroin. The as-fabricated hydrogel (named rGO/SF hydrogel) exhibits superior stretchability and compressibility, which makes it possible to realize multiple signal detection. When used as a strain sensor, its tensile deformation can reach more than 100%, and it can detect various human motions such as finger, wrist, knee, and elbow movements, breath on chest, and speech recognition. For pressure detection, it displays a wide sensing range from 100 Pa to 500 kPa with high sensitivity, which enables it to discriminate pulse signals at different locations of the wrist, and also its changes before and after exercise. Moreover, benefiting from its desirable performance with respect to piezoresistive properties, a wearable gesture recognition system with high accuracy is developed by attaching five pressure sensors on a smart glove, demonstrating its potential application prospects in human–machine interactions and physical training and medical diagnostics.