High-Performance Piezoresistive Sensors via Pd/Sn-Free Graphene-Catalyzed Metallization of Thermally Repairable Microfiber Scaffolds.

A Pd/Sn-free, thermally repairable piezoresistive pressure sensor is reported based on electrospun poly(ε-caprolactone) microfibers metallized through a graphene-mediated electroless copper process. The conformal graphene interlayer provides catalytic defect sites and electron-rich domains for uniform Cu nucleation while reinforcing the Cu-polymer interface, yielding a porous PCL/graphene/Cu core-shell scaffold with robust electrical and mechanical integrity. The multilayer sensor exhibits a sensitivity of 280.9 kPa-1 over 0.098-200 kPa with good linearity (R2 = 0.905), a response/recovery time of 69.3/69.2 ms, and stable operation over 100 000 loading cycles at 100 kPa. The metallized scaffold retains fiber morphology and sensing capability after exposure to 180°C, while damage recovery is enabled by thermally induced softening and reconnection of the PCL core at 80°C. After repeated cut-and-repair cycles, the device restores > 95% conductivity and > 90% mechanical strength within 15 min. A 6 × 6 sensor array further enables spatial mapping of loads as low as 1 g with minimal crosstalk, highlighting a practical platform for repairable wearable and tactile sensing.