Fingerprint-Inspired Flexible Capacitive Sensor for Multi-Directional Tangential Force Sensing via Laser-Etched Geometry

Current flexible tactile sensors mainly focus on normal-pressure detection, while reliable sensing of directional tangential loads remains comparatively less explored, particularly for object manipulation in intelligent robotic systems. Inspired by the ability of human fingers to perceive directional tangential mechanical stimuli during contact, we developed a spiral-structured flexible biomimetic capacitive sensor using a laser-etching-assisted fabrication strategy. The spiral electrode architecture enables multi-directional detection of in-plane tangential forces. In the tested range, the device exhibited a maximum tangential-force sensitivity of 0.107 N ^− 1 , a detection range of 0.1–10 N, response/recovery times of approximately 50 ms, and stable operation over 5,000 loading cycles. These results suggest potential applications in wearable tactile interfaces, robotic manipulation, and proof-of-concept electronic-skin systems.