Highly Stretchable, Transparent, and Self-Adhesive Ionic Conductor for High-Performance Flexible Sensors

Abstract

Different from conductive hydrogels, ion gels, another kind of ionic conductor, possess excellent nonvolatility and anti-freezing capability, which have attracted increasing research interest in electronic field. Nevertheless, the poor mechanical property of ion gels severely hinders their application in flexible strain sensors. Herein, an ionic conductor composed of poly(acrylic acid) (PAA) within the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([BMIM]TfO) was synthesized by facile one-pot photopolymerization. The resulting ion gel exhibited extreme stretchability (1200%), high transparency (over 90%), good environmental stability, and outstanding self-adhesion. The remarkable electromechanical characteristics, including fast response speed, high sensitivity, low electrical hysteresis, and autonomous repeatability, endow the PAA ion gel with superior strain-sensing capability to monitor various human motions. Additionally, the PAA ion gel displayed rapid response speed and high sensitivity to temperature change. Therefore, this multifunctional ion gel-based flexible bimodal sensor provides broad prospects for wearable electronics.