Zwitterionic Cellulose Hydrogels for Flexible Strain Sensors with Enhanced Sensing and Mechanical Performance

Abstract

Conductive hydrogels combine flexibility, conductivity, and adaptability, making them ideal for flexible strain sensors. However, achieving multifunctional performance under freezing conditions remains challenging, as flexibility, adhesion, and conductivity often deteriorate at high or low temperatures. In this work, we introduce a polyzwitterion-hydroxyethylcellulose (HEC) hydrogel that transforms into a freeze-resistant ion-conducting material. The mechanical properties and ion conductivity of this hydrogel are enhanced through an optimized composition, with HEC's structure playing a crucial role in its performance. The interconnected network, fortified by intermolecular forces and charged polar end groups, delivers exceptional properties, including a tensile strength of 54 kPa, a gauge factor of 1.63, and a response time of 2.11 s. These characteristics enable the hydrogel sensor to accurately monitor human motion, establishing an ideal platform for iontronics, soft robotics, and advanced health diagnostics.