A Battery-Free Wireless Tactile Sensor for Multimodal Force Perception

Multimodal tactile sensors, as key information input channel in human-machine interactions, have faced the significant challenges including high power-consumption, multimodal data fusion, and wireless transmission. In this work, a battery-free multimodal wireless tactile sensor (TC-MWTS) based on tribo-capacitive coupled effect for normal and shear force fusion sensing is proposed, which is enabled by a 3D structure combining a triboelectric sensor and a capacitive sensor coupled with an inductive coil. A triboelectric sensor equipped with contact-discharge structures exhibits 25-fold wireless signal enhancement compared to conventional triboelectric sensors. Based on the characteristics of dual time-frequency domain information existing in the wireless signals, both normal and shear forces can simultaneously be converted into voltage amplitude V and eigenfrequency f, respectively, without crosstalk and complex decoupling signals. The TC-MWTS exhibits a maximum sensitivity of 2.47 V kPa⁻¹ for normal force from 2 to 30 kPa and a sensitivity of 0.28 MHz N⁻¹ for shear force between 0.3 and 1.0 N. Finally, the excellent sensing capability of TC-MWTS to sense complex multidimensional forces in human-machine interaction is demonstrated. This work innovatively proposes a new mechanism and methodology for effectively fusing and processing multimodal tactile information, which may drive the tremendous development of low-power multimodal tactile sensing system.