Superhydrophobic/Conductive Paper-Based Composite with High Moisture Tolerance, Antifouling, and Pressure-Sensing Function through Synergistic Reinforced Surface Coating

Conductive paper-based composites, which serve as wearable sensors, demonstrate significant potential in the field of flexible electronic devices due to their excellent degradability, biocompatibility, simple manufacturing processes, and low cost. However, conventional paper-based electronics face challenges in humid environments due to inherent hydrophilicity, especially under water, which is a critical issue in many applications. Herein, a superhydrophobic and conductive paper-based composite (D-paper) was developed via a synergistic dual-layer coating strategy to achieve high moisture tolerance, antifouling, and pressure-sensing functions. The synergistic effect between the inner MXene coating and the outer octadecyltrichlorosilane-functionalized carbon black (OTS-CB)/wax composite coating endowed the D-paper sensor with outstanding pressure-sensing performance, including an ultralow pressure detection limit of 0.25 g and a fast response/recovery time of 100/130 ms. Importantly, the robust superhydrophobic surface, originating from the outer coating, could resist even 30 tape-peeling cycles, 0.8 m sandpaper abrasion, 1200 finger-pressing cycles, and 200 drop-weight impacts (50 g, 30 cm), 40 s water impacting, while 8 h NaCl, 1.5 h HCl, and 1 h NaOH solutions immersion. It further ensured long-lived and reliable human motion monitoring (finger pressing, treading, muscle contraction, and joint bending) under various environments, including normal, rainy, and underwater conditions. This study provides a scalable approach to multifunctional paper-based sensors, overcoming the limitations of conventional hydrophilic devices in humid/contaminated scenarios.