Wearable, Washable, and Highly Sensitive Piezoresistive Pressure Sensor Based on a 3D Sponge Network for Real-Time Monitoring Human Body Activities

Wearable pressure sensors are highly desirable for monitoring human health and realizing a nice human–machine interaction. Herein, a chitosan/MXene/polyurethane-sponge/polyvinyl alcohol (CS/MXene/PU sponge/PVA)-based 3D pressure sensor is developed to simultaneously achieve wearability, washability, and high sensitivity in a wide region. In the force-sensitive layer of the sensor, MXene and CS are fully attached to the PU sponge to ensure that the composite sponge has remarkable conductivity and washability. Benefiting from the highly resistive PVA-nanowire spacer, the initial current of the sensor is reduced significantly so that the sensor exhibits extremely high sensitivity (84.9 kPa^–1 for the less than 5 kPa region and 140.6 kPa^–1 for the 5–22 kPa region). Moreover, the sensor has an excellent fast response time of 200 ms and a short recovery time of 30 ms, as well as non-attenuating durability over 5000 cycles. With the high sensitivity in a wide range, the sensor is capable of detecting multiple human and animal activities in real time, ranging from the large pressure of joint activities to a subtle pressure of pulse. Furthermore, the sensor also demonstrates the potential application in measuring pressure distribution. Overall, such a multifunctional pressure sensor can supply a new platform for the design and development of wearable health-monitoring equipment and an efficient human–machine interface.