Highly elastic, fatigue-resistant and highly conductive poly(lipoic acid)-based liquid-free ionic conductive elastomers for wearable sensors

Abstract

Flexible ionic conductive elastomers have garnered significant attention owing to their promising applications in flexible wearable devices. The challenges posed by water evaporation in hydrogels and the leakage of ionic liquids in ionogels have motivated researchers to develop liquid-free ionic conductive elastomers (ICEs). However, the development of liquid-free ICEs that simultaneously exhibit excellent resilience, full recyclability, high conductivity, mechanical robustness and self-healing capability presents a significant challenge. Here, a high entanglement network is constructed through the modification of poly(lipoic acid) sidechains and the formation of lithium bonds, which endows ICE with high tensile strength (140 kPa), stretchability (626 % elongation at break), and excellent resilience (96.74 % peak stress retention rate after 1000 cycles at 100 % strain). Notably, the mechanical properties, ionic conductivity, and resilience of ICE can be enhanced simultaneously due to the formation of lithium bonds. Moreover, the ICE features full recyclability (up to three times) and self-healing efficiency (78.1 %). A strain sensor based on the designed ICE enables gesture recognition. The assembled triboelectric nanogenerator based on ICE can detect human motion and encrypt information. This research provides valuable insights into the design of liquid-free ICEs with unparalleled combinatory properties toward reliable and environmentally sustainable wearable flexible device.