Ultra-compact single-electrode triboelectric nanogenerators for self-powered wear sensing of reciprocating sealings

Intelligent mechanical sealing is crucial for the advancement of equipment intelligence and the Internet of Things (IoT), as it effectively addresses significant challenges such as the monitoring of mechanical seals in high-end equipment. However, the limited reliability of indirect measurements and the compromises in the structural integrity of the original seal caused by implantable measurements pose constraints on the efficacy of monitoring wear in seals. Here, this study proposes a smart ultra-compact triboelectric reciprocating sealing system (UC-TERS) capable of monitoring motion states and wear conditions. By utilizing the existing structure of commercial seals and applying abrasion-resistant coatings to the moving parts, the UC-TERS enables an ultra-compact design. The electrical output performances of various materials were investigated, and diamond-like carbon (DLC) coating and sealing made of polytetrafluoroethylene (PTFE) mixed with carbon fiber were selected to improve the self-powering and self-sensing capabilities. Variations in the output voltage and current caused by the load resistance were measured. Experiments involving various speeds and a constant speed were conducted to verify the self-sensing ability of the UC-TERS in detecting the motion state. In addition, a sealing wear test was performed to diagnose the wear conditions in the reciprocating mechanism based on the UC-TERS output. By combining the UC-TERS with deep learning algorithms, different wear conditions were accurately classified. Subsequently, the UC-TERS was applied to industrial servo actuators, and it demonstrated that it could achieve self-powering and self-sensing capabilities with a high reliability. The results of this study showcase the broad application potential of UC-TERS in the development of IoT.