Flexible Wide-Range Triboelectric Sensor for Physiological Signal Monitoring and Human Motion Recognition

Triboelectric nanogenerators, as a device that converts mechanical energy into electrical energy, can respond to external pressure stimuli. However, most triboelectric sensors can only perform pressure measurements in a narrow pressure range, which limits their application in multiple scenarios. Here, we proposed a wide-range triboelectric pressure sensor based on the difference in Young's modulus of the materials and a double-sandwich-structure design. We analyzed the effect of the structural angle at the material surface on the sensor performance and obtained an optimal combination of angles for a double-sandwich-structure sensor. The proposed sensor has outstanding performance including high sensitivity (249.32 mV/kPa), wide range (0-450 kPa), and fast response time (26 ms). Meanwhile, the sensor has a quite low detection limit (8.72 Pa). The designed sensor can be applied not only to the detection of small physiological signals but also to large plantar pressure sensing. A human motion recognition system based on plantar pressure was developed. Moreover, we also designed a convolutional gated recurrent unit model to recognize four human motions with high accuracy (99.42%). This work provides a design idea to extend the range of the triboelectric sensor to meet multiple applications.