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.

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Rotation detection is widely applied in industries. The current commonly used rotation detection system adopts a split structure, which requires stringent installation requirements and is difficult to miniaturize. This paper proposes a single-piece self-powered non-contact sensor with an interdigital sensitive layer to detect the rotation of objects. The electric field generated between a polyurethane (PU) film and a polytetrafluoroethylene (PTFE) film is utilized for perceiving the rotation. The surface of the PU film is subjected to wet etching with sulfuric acid to increase the surface area and charge density. Through finite element analysis and experimental testing, the effects of the areas of the sensitive films as well as the horizontal and vertical distances between them on the output voltage are analyzed. Tests are performed on adjustable-speed motors, human arms, and robotic arms. The results show that the sensor can detect the speed, the transient process of rotation, and the swing angle. The proposed rotation sensor has broad application prospects in the fields of mechanical automation, robotics, and Internet of Things (IoT).