A Double-Network Hydrogel for Multimodal Pressure-Temperature Sensing and Assistive Communication

Flexible multimodal sensors capable of simultaneously monitoring pressure and temperature are highly desirable for wearable healthcare, physiological monitoring, and human-machine interaction. However, signal crosstalk between different stimuli remains a major challenge that limits sensing accuracy and practical deployment. Herein, a dual-mode flexible sensor based on a polyacrylamide/chitosan (PAM/CS) double-network hydrogel is developed through a one-pot polymerization strategy. By incorporating a sandwich-structured architecture with independent capacitive and resistive output channels, pressure and temperature stimuli are selectively transduced into capacitance and resistance signals, respectively, enabling effective signal decoupling. The hydrogel exhibits an elongation at break of 2620%, while the sensor achieves a pressure sensitivity of 155.91 kPa^{- 1}, response/recovery times of 205/163 ms, and stable operation over 1500 loading cycles. In addition, the sensor demonstrates a wide temperature sensing range of 30°C-120°C with a sensitivity of -0.38％°C^{- 1} and a response time of 480 ms. Benefiting from its excellent mechanical and sensing performance, the device enables real-time monitoring of joint motion, pulse signals, and respiratory activities. An adaptive Morse-code decoding system is demonstrated for pressure-driven information transmission and assistive communication. This work provides a simple strategy for constructing structurally decoupled multimodal hydrogel sensors for wearable electronics and human-machine interfaces.