Multimodal Flexible Sensors Based on Porous Laser-Induced Graphene with Tunable Thermal Therapy and Haptic Perception

Abstract Laser-induced technology on polyimide(PI) substrates, as an effective and simple method, is used to prepare patterned and large-area graphene for application in healthcare monitoring and human motion sensing. However, laser-induced graphene on PI substrates has some limitations in healthcare monitoring and human motion sensing due to low skin compatibility and nonstretchability issues. Therefore, PDMS-LIG-PDMS wearable and flexible sensor is prepared by the semi-solid-state transfer (S3T) strategy, which can achieve the high-quality and rapid transfer of LIG by precisely controlling the polydimethylsiloxane (PDMS) curing process (cured at 70 °C for 20 min to reach a semi-solid state). The as-fabricated PDMS-LIG-PDMS flexible sensor (P-LIG-PFS) exhibits a rapid response of 250 ms and a stable cycling life of over 10,000 s. Benefiting from the unique mechanism coupling microcrack propagation and transverse tension, the sensor demonstrates piecewise high sensitivity over a wide working range: within the pressure range of 0–40 kPa, the sensitivity is 1.948 kPa–1 in the 0–20 kPa interval and reaches a peak of 5.599 kPa–1 in the 26–34 kPa interval; within the tensile strain range of 0–40%, the gauge factor (GF) significantly increases from 7.440 in the 0–20% interval to 24.982 in the 30–40% interval. In addition, the sensor can not only be integrated into a mechanical claw to achieve tactile perception of various objects, but also provide thermotherapy for the human body, demonstrating broad application prospects in wearable medical devices and humanoid robotics.