Dual-Mode Capacitive Sensor Based on MXene/Au-Functionalized Sponge for High Sensitivity Pressure and Long-Range Proximity Sensing

Capacitive pressure sensors have garnered considerable attention for applications in wearable electronics, human-machine interfaces, and artificial intelligence. However, achieving sensitive simultaneous detection of pressure and proximity remains challenging. Herein, we report a flexible capacitive sensor comprising a melamine sponge (MS) interlayer functionalized with Ti3C2Tx MXene/gold nanoparticle (MXene/Au) nanocomposites, which is integrated into a conventional metal-insulator-metal architecture. The resulting sensor exhibits high pressure sensitivities of 0.56, 0.24, and 0.08 kPa-1 over pressure ranges of 0-0.3, 0.3-2.5, and 2.5-5.0 kPa, respectively, along with a fast response time of 30 ms and excellent durability over 6000 cycles at 2.5 kPa. Moreover, it demonstrates remarkable non-contact sensing capability with a detection distance of up to 25 cm. We explored its potential in monitoring finger bending, grasping, wrist pulses, swallowing, and ocular muscle movements during blinking. Collectively, this work offers valuable insights into the design of high-performance flexible sensors for human motion monitoring and non-contact sensing.