Complete contact trajectory visualization based on triboelectrification and droplet luminescence

• Developed a motion trajectory storage system with mechanoluminescent particles. • Motion trajectory can be visualized on the flexible film using water mist spraying. • Combined droplet-luminescence & triboelectrification to display motion trajectory. • The complete trajectory and magnitude of the applied force are both displayed. Motion-driven light generation is being widely investigated for application in sensors, lighting, anticounterfeiting, displays, and artificial skin owing to its unique mechano-optical response feature. However, trajectory visualization in these applications frequently requires an auxiliary device, thereby increasing the size of the overall system. Furthermore, an additional power supply is required for auxiliary devices. In this study, contact trajectory visualization is directly realized by utilizing triboelectric charges on a rubbed surface without an auxiliary device. Functional film material for trajectory storage and display is fabricated based on triboelectrification-induced electroluminescence (TIEL). When a glass rod slides on the functional film surface, the functional film stores the motion trajectory, which can then be easily visualized by applying a polar-liquid mist. Moreover, the magnitude of the applied force is reflected by the light intensity of the trajectory. This functional film exhibits broad applicability and good stability. The entire process is straightforward and can easily be applied in mechanical motion-driven systems such as sensors or handwriting recording. The proposed solution simplifies existing motion-driven light generation systems.