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

The slippage of moisture-sensitive materials from substrates during bending or stretching is a common issue that causes baseline drift and even failure of the flexible humidity sensors, which are essential components of wearable electronic devices. In this study, we report a stretchable, self-adhesive, and transparent humidity-sensing electronic patch comprising liquid metal particles electrodes with a stretchable serpentine structure and a humidity sensing layer made of Ti3C2Tx MXene /carboxymethyl cellulose. This patch is constructed on a soft-hard integrated heterostructure substrate and demonstrates stable humidity-sensitive response performance at 100% tensile strain, along with autonomous adhesion to human skin. Additionally, it exhibits high sensitivity, fast response, and stability of humidity sensing, as well as easy scalability for multiplexed detection. We further illustrate the patch's potential applications in healthcare and environmental monitoring through a non-contact security door control system and wind monitor system. Our proposed strain-isolation strategy can be extended to other rigid conductive materials and stretchable substrates, providing a new and efficient way for high-performance wearable electronics.