Long-Term Stability and Excellent Sensing Performance of Poly(vinyl alcohol)/Polyacrylamide/Ta₄C₃T_X Hydrogel Sensors

Abstract

The subpar mechanical and electrical properties of traditional conductive hydrogels limit their applicability in flexible pressure sensors for the stable and real-time monitoring of human activities. In this study, we synthesized a double-network poly(vinyl alcohol)/polyacrylamide/Ta4C3TX hydrogel using a one-pot polymerization method in the presence of CaCl2. This hydrogel benefits from the coexistence of metal coordination bonds, hydrogen bonds, and ionic interactions, contributing to its desirable mechanical properties and good compressibility. Furthermore, the incorporation of Ta4C3TX MXene significantly enhances the conductivity of the hydrogel compared to the pristine poly(vinyl alcohol)/polyacrylamide variant. The piezoresistive sensors constructed from this hydrogel demonstrate a high sensitivity of 2.67 kPa–1, a low detection limit of 38 Pa, a rapid response time of 69.1 ms, and a short-term recovery time of 39.75 ms, all while maintaining good stability. Notably, the sensors retain excellent sensing performance even after 90 days. Given these outstanding characteristics, the sensors hold promise for monitoring physiological signals, such as those from human limbs and speech, and can be utilized in the fields of detecting robotic movement and wireless wearable sensing. Additionally, the hydrogel demonstrates exceptional thermal shielding properties. This high-performance hydrogel developed in this study paves the way for advanced flexible wearable electronic devices.