Highly sensitive flexible pressure sensor based on MXene and NH2-CNTs enhanced sponge structure for human activity monitoring

Multifunctional flexible pressure sensors have garnered significant interest for their potential in health monitoring, electronic skin, and human-machine interfaces. However, sensors fabricated by simple physical blending often suffer from weak interfacial bonding, which leads to the detachment of conductive materials under repeated deformation. To address this issue, we propose an innovative strategy by incorporating aminofunctionalized carbon nanotubes (NH 2 -CNTs) into an MXene/polyurethane (PU) sponge system. Driven by strong electrostatic interactions between NH 2 -CNTs and MXene, a robust and interconnected conductive network is constructed through an electrostatic layer-by-layer self-assembly process. The resulting MXene/NH 2 -CNTs/PU sponge exhibits remarkable overall performance, featuring high sensitivity (0.387 kPa −1 ), rapid response/recovery times (82/83 ms), a wide detection range (0–55 kPa), an ultralow detection limit (11 Pa), and excellent cyclic stability (>5000 cycles). Benefiting from its wide detection range and high sensitivity, the sensor enables real-time monitoring of diverse physiological signals, from subtle acoustic vibrations of the vocal cords to full-range body movements. Coupled with its facile and low-cost fabrication process, the multifunctional MXene/NH 2 -CNTs/PU sponge sensor paves the way for broad applications in human activity monitoring and beyond.