Structure and Interfacial Modulation of Triboelectric Sensors for Sitting Posture Monitoring.

The output performance of triboelectric sensors (TESs) still encounters some limitations, such as interface charge recombination and incomplete contact during deformation. This study improves the performance of TESs by integrating material interface engineering with structural design. A 1-mm-thick hydrogel generates the strongest interfacial polarization electric field, reducing the charge recombination rate from 25.6% to 4.1%. Meanwhile, optimizing the hydrogel thickness improves structural compliance and enlarges the effective contact area. Therefore, a 3-mm-thick hydrogel achieves the maximum surface charge density of 219 μC·m-2 by balancing charge-recombination suppression and effective contact status. Additionally, the spacer gap of TES is optimized to regulate contact evolution during deformation, consistent with the Föppl-von Kármán large-deflection model. The combined theoretical and experimental analyses clarify the roles of interfacial polarization and structural deformation in output enhancement. The optimized TES further enables sitting-posture recognition, demonstrating its potential for health monitoring.