Solvent-free adhesive ionic elastomer for multifunctional stretchable electronics

Abstract

Intrinsically stretchable and transparent ionic conductors are of great interest due to their promising applications in flexible and wearable electronics. However, hydrogels/organogels based devices suffer from instability due to liquid evaporation or leakage. Herein, we present a solvent-free ionic elastomer (IE), featuring high transparency (>92%), stretchability (300%), ionic conductivity (0.07 mS/cm), adhesiveness (61 N/m), thermal stability (300 °C), and negligible mechanical hysteresis, which endows implementation capacity in multifunctional stretchable electronics. The IE-based robust strain sensors (both resistive and capacitive) show linear sensitivities in the range of 0–150% strain and long-term stability. Moreover, a reversible wide-range temperature sensor is presented showing remarkable sensitivity in the range of 30–55 °C sustained under 50% stretching. The temperature-strain effect on the IE-based sensor is insignificant, ensuring an accurate sensing capability. Thanks to its self-adhesiveness, a fully integrated, stretchable motion energy harvester as well as a skin-like thin triboelectric sensor array using IE as the electrode are further designed to demonstrate efficient human motion energy harvesting with a peak power density of 3.6 W/m2 and self-powered tactile sensing. The results provide strategies towards potential applications of developed IE in healthcare monitoring systems, biomechanical energy harvesting, soft robotics, and human-machine interfaces.