High-Performance Epidermal Strain Sensor Based on Macro-Defect Graphene Foams

Abstract Three-dimensional (3D) epidermal sensing components featuring broad working range, excellent sensitivity and high signal-to-noise ratio (SNR), have attracted great interest for the fast developing wearable electronic systems. Herein, an efficient optimization of the sensitivity of graphene foams (GrF) based strain sensors is reported by making macroporous structure in the framework. The macron-scale hole makes the GrF more fragile points and leads to the resistance change signal more detectable under micro-deformation. The analysis of the comparative experiments shows that the macroporous structure could significantly increase the sensitivity of the 3D graphene-elastomer composite, endowing the piezoresistive sensor with a maximum gauge factor (GF) as high as 30 (about 10 times of pure GrF device) and a wide sensing range up to 20 %. In addition, the stretchable and biocompatible strain sensor can be easily attached on human skin as the wearable electronics, which shows ultrahigh SNR in real-time detection of human motion and typical acoustic waves. The rational design of macroporous structure provides an efficient, economical, and environmentally friendly strategy for electromechanical properties optimization, which may be valuable for designing and fabricating other high performance smart electronics.