Waterproof Flexible Pressure Sensors Based on Electrostatic Self-Assembled MXene/NH₂-CNTs for Motion Monitoring and Electronic Skin

Flexible wearable sensors to monitor human movement andfor electronicskins must exhibit high sensitivity, a wide detection range, and waterproofcharacteristics. This work reports a flexible, highly sensitive, andwaterproof sponge pressure sensor (SMCM). The sensor is made by assemblingSiO(2) (S), MXene (M), and NH2-CNTs (C) on thebackbone of melamine sponge (M). The SMCM sensor exhibits excellentsensitivity (10.8 kPa(-1)), an ultra-short response/recoverytime (40 ms/60 ms), a wide detection range (30 kPa), and an extremelylow detection limit (4.6 Pa). Benefiting from layer-by-layer self-assembly,the sensor still exhibits excellent stability after 5000 cycles. Inaddition, the SMCM sensor also has excellent waterproof performance(a water contact angle of 142 & DEG;), enabling it to operate unaffectedlyunder wet conditions. The SMCM sensor can accurately detect smallbody movements such as pulse and swallowing while also accuratelydetecting finger and elbow movements. In addition, the sensor canbe designed as an array to construct an electronic skin for detectingthe magnitude and distribution of external pressure. This work holdsgreat application potential in next-generation electronic skin, fitnessdetection, and flexible pressure sensors.