Multifunctional SBS-Based Strain Sensor on Interfacial Self-Assembly with Synergistic Conductive Network for Human Motion Recognition and Thermal Management

Flexible strain sensors based on styrene-butadiene-styrene block copolymers (SBS) face challenges such as low sensitivity, poor multifunctional synergy, complex fabrication processes, and high costs in practical applications. In this study, we present a facile strategy for fabricating graphene-carbon nanotube (Gr-CNTs)/SBS composite films (GCSCF) through an oil-water interfacial self-assembly process. This approach enables the selective embedding of Gr-CNT hybrid conductive particles on one surface of the SBS substrate, while preserving the opposite side as an insulating layer. The mechanism of the film's synergistic conductive network involves Gr constructing a continuous conductive framework, with CNTs interspersing and filling the gaps in the framework. Microcrack structures were introduced on the Gr-CNTs-embedded side of GCSCF via a prestretching process. The synergistic conductive network endows the sensor with a wide response range, whereas the microcrack structures confer high sensitivity, with a maximum gauge factor (GF) of 63,932 within the strain range of 110-132.5%. As a flexible strain sensor, GCSCF exhibits a strain detection range of 0.05-132.5% and rapid response/recovery times of 126 and 112 ms, respectively. Notably, it is capable of full-range human motion signal detection, human-computer interaction, electronic skin, and underwater signal transmission. More importantly, the flexible GCSCF exhibits excellent Joule heat management performance (driving voltage: 4-10 V; surface temperature reaches 40-64 °C under corresponding voltages, all below the 36 V human safety threshold) and can also be used as a temperature-sensitive sensor.