Mechanically Robust Gelatin Gel for Sensitive Touch Sensor Based on Electrode Potential

Abstract

Gelatin hydrogel with excellent biodegradability and biocompatibility is widely used in drug delivery, electronic devices, and flexible sensors. However, it is prone to dehydration, which severely restricts its applications. The incorporation of hydrated ions, for example choline chloride (ChCl), can not only improve its water retention capacity but also keep its biocompatibility. Unfortunately, the improvement in water retention is realized at the expense of mechanical properties because the ChCl can suppress the crystallization of gelatin. Here, ChCl is introduced into gelatin hydrogel using a simple post-treatment to simultaneously improve its water retention capacity and mechanical properties. As a result, the resultant gelatin gel possesses a maximum fracture strength of 5.4 MPa with a strain of 623% and can maintain its weight for at least 30 days. In addition, the gelatin gel exhibits intriguing properties, such as self-healing, anti-freezing, anti-drying, recycling, conductivity, and moldability, which can be successfully served as wearable sensors to monitor human movements. Further, a sensitive touch sensor based on electrode potential is established for the first time using the obtained gel, which can transmit messages through the touch potential signal.