Anti-freezing conductive hydrogels with exceptional mechanical properties and stable sensing performance at −30 °C

This is the authors' abstract. We don't add key points for this paper.

Conductive hydrogels with stable sensing performance are highly required in soft electronic devices. However, these hydrogels tend to solidify and experience structural damage at sub-zero temperatures, leading to material breakdown and device malfunction. The main challenge lies in effectively designing the micro/nano-structure to enhance mechanical properties and stable strain sensing while preventing freezing in hydrogels. Here, we present a rapid strategy for developing a MXene bridging double-network structure-based strain sensor using polyacrylamide and agar hydrogels that can maintain stable functionality even at an extremely low temperature of -30 °C. By incorporating MXenes as a catalyst to expedite free radical polymerization, we achieve outstanding mechanical and strain sensing properties at room temperature (a high response range of 1000%, a response signal linearity of 0.998, and a gauge factor (GF) value of 1.41). This sensing performance surpasses those reported for many other hydrogels. Importantly, we also observe that the stable micro-nanostructure in the hydrogel at an extreme temperature of approximately -30 °C results in exceptional strain-detection performance (a stable response range of up to 250%) with a linearity of 0.995 and a GF value of 1.25 due to its remarkably low freezing point (<-80 °C). These findings highlight the application of our hydrogel-based tactile sensor in low-temperature environments.