Stretchable and Self-Adhesive Humidity-Sensing Patch for Multiplexed Non-Contact Sensing

The slippage of moisture-sensitive materials from substratesduringbending or stretching is a common issue that causes baseline driftand even failure of the flexible humidity sensors, which are essentialcomponents of wearable electronic devices. In this study, we reporta stretchable, self-adhesive, and transparent humidity-sensing electronicpatch comprising liquid metal particle electrodes with a stretchableserpentine structure and a humidity-sensing layer made of Ti3C2T x MXene/carboxymethyl cellulose.This patch is constructed on a soft-hard integrated heterostructuresubstrate and demonstrates stable humidity-sensitive response performanceat 100% tensile strain, along with autonomous adhesion to human skin.Additionally, it exhibits maximum response (1145.4%) at 90% relativehumidity (RH), fast response and recovery time (1.4/5.9 s), elevatedsensitivity (64.63%/% RH), and preserved humidity sensing under deformation,as well as easy scalability for multiplexed detection. We furtherillustrate the patch's potential applications in healthcareand environmental monitoring through a non-contact security door controlsystem and wind monitor system. Our proposed strain-isolation strategycan be extended to other rigid conductive materials and stretchablesubstrates, providing a feasible mechanism for producing stretchableelectronic skin patches.