A self-powered triboelectric sensing approach for stiffness matrix characterization and critical load prediction of cantilever structures

Self-powered vibration sensors have attracted increasing attention for structural characterization and autonomous monitoring due to their ability to operate without external power sources. In this work, a self-powered triboelectric sensing approach is introduced to enable stiffness-related characterization of cantilever structures through free-end integration of a contact–separation-mode milk-white poly(ethylene terephthalate) (PET)-based triboelectric nanogenerator (M-TENG). The M-TENG employs milk-white PET and polytetrafluoroethylene as the positive and negative triboelectric layers, respectively, forming an effective triboelectric interface. Under periodic excitation, the device delivers high and stable electrical output, achieving an open-circuit voltage (VOC) of ∼179.2 V, a short-circuit current (ISC) of about 21.5 μA, and a transferred charge (QSC) of roughly 64.2 nC, with a maximum output power of around 520 μW. When coupled with a cantilever structure, the electrical output increases monotonically with vibration displacement and shows clear dependence on sensor position and excitation direction. These spatially and directionally dependent responses provide electrically encoded information relevant to stiffness-related structural behavior, establishing a viable basis for stiffness matrix characterization and offering a feasible pathway toward critical load prediction.