High-performance flexible dual strain-temperature sensor based on a sandwich-architecture hydrogel

Developing high-performance hydrogel sensors that simultaneously offer skin compatibility, mechanical/thermal sensitivities and outstanding durability is essential for skin-mimicking applications. However, simultaneous realization of multifunctionalities in a single hydrogel sensor remains a significant challenge. Herein, a sandwich architecture hydrogel sensor with synergistic excellent mechanical/thermal dual-sensitivity was constructed. Leveraging a multilayer architecture, the sensor achieves a dual response to mechanical stress/strain and temperature variations. Based on a poly(acrylic acid) (PAAS)-polyacrylamide (PAM) interpenetrating network hydrogel, the sensor ensures exceptional mechanical flexibility. The incorporation of poly(N-isopropylacrylamide) (PNIPAM) imparts thermosensitivity, while a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/graphene composite interlayer significantly enhances electrical conductivity. Performance evaluations demonstrate that the sensor exhibits high sensitivity (gauge factor up to 25.76), remarkable durability (exceeding 5000 cycles), and pronounced conductivity. Furthermore, the sensor successfully achieves effective monitoring of electrical signals associated with human joint and torso movements and displays outstanding thermal sensitivity (temperature coefficient up to 8.33 pph °C^-1, reaching 16.96 pph °C^-1 within a specific temperature range), positioning it as a promising candidate for applications in physiological inflammation monitoring and body temperature fluctuation tracking.