Triboelectric nanogenerators (TENGs), which convert mechanical energy into electrical signals, have emerged as apromising platform for self-powered motion sensing. However, the development of high-sensitivity TENG sensors remains limited by the availability of tunable and efficient tribo-positive materials, which are electron donors. In this work, we present a material design strategy based on the incorporation of electron-donating functionalized metal-organic framework (MOF) fillers into a polyurethane (PU) polymer matrix. Three functional groups (-CH3, -NH2, and -OH) were systematically studied to investigate their influence on triboelectric performance. The resulting composite membranes demonstrated tunable charge-donating behavior and improved electrical output, with the -OH-modified MOF yielding the highest electrical output of 197.6 ± 1.3 V and 0.47 ± 0.08 μA/cm2, which are 2.3 and 3.2 times higher than that of the pristine PU. The enhanced charge-donating mechanism was elucidated through a combination of advanced micro- and nanoscale chemical and mechanical analysis. Theoretical calculations employing ab initio density functional theory (DFT) were performed to reveal the electron distribution within the periodic MOF structure. Furthermore, the practical application of the optimized TENG device was demonstrated in a single-electrode shear sensor configuration, exhibiting high sensitivity in sliding motion detection. This study highlights a scalable and biocompatible strategy for improving tribo-positive materials and advancing the performance of tunable TENG-based sensors to enable shear force monitoring.
Xu et al. (2026) studied this question.