Self-Powered Multifunctional Triboelectric Sensor Based on PTFE/PU for Linear, Rotary, and Vibration Motion Sensing

Sensors used in the Internet of Things (IoT) should be cost-effective and easy to maintain. Triboelectric sensors made of polymers have good development prospects. Herein, a self-powered multifunctional motion sensor (MMS) is proposed to sense the speed, acceleration, and direction of linear and rotational motions, and detect the frequency of vibration. The MMS comprises a polyurethane (PU) ball encapsulated in a 3D-printed cylindrical shell, the inner walls of which are lined with Cu electrodes coated with a polytetrafluoroethylene (PTFE) film. The scanning electron microscopy results show that the surface area of the PU ball can be effectively increased through wet etching with sulfuric acid. The charge transfer law is analyzed and simulated using the finite element method. The finite element simulation and experimental results prove that the MMS exhibits a good sensing performance. The MMS is successfully applied to the motion detection of a self-balancing scooter and human activity state. It can also detect small vibrations and rotational speed. The proposed MMS has broad application prospects in the field of IoT.