Multi-Arches Structured All-Carbon Aerogels with Super Elasticity and High Fatigue Resistance As Sensitive Wearable Sensors

摘要

Lightweight, conductive and flexible all-carbon aerogels are promising candidates for piezoresistive sensors. Although there are several techniques developed to produce aerogels, the required flexibility and ductility of all-carbon aerogels are yet to be satisfied due to the structure-derived fatigue failure and energy loss. Herein, we present a two-stage solvothermal freeze-casting approach to fabricate multi-arch structured all-carbon aerogel. Our results and calculations reveal that such a multi-arch shaping is enabled by the solvothermal reduction of graphene oxide and unidirectional "bottom-up" ice-crystal growth. Systematic investigations on stress-strain performances indicate that the multi-arch all-carbon aerogel produces anisotropic fatigue-resistive behaviour in both axial and radial directions under 80% strain and exhibits lower mechanical energy loss coefficient (0.03) in the radial direction. Further ball-falling test indicates that the aerogel can rebound the ball (1400 times heavier than the aerogel) in 0.13 s with a fast recovery speed (720 mm s~(-1)). The remarkable mechanical ductility and conductivity endow the aerogel with high-performance piezoresistivities, such as a wide sensing pressure range (1.43～13.56 kPa), tunable linear sensitivity (9.13～7.29 kPa~(-1)) and incremental gauge factor (38～118). The aerogel is processed as a wearable pressure sensor, which can measure tiny pulses and sound vibrations of an adult. The results reveal that it has high sensitivity with fast response (96 ms) and low power consumption (4 mW), demonstrating its potential practicability in monitoring human healthy activity and distinguishing sounds.