Decoupling dynamic touch signals in optical tactile sensors is challenging due to limitations in measuring dynamic forces. This paper presents a highly sensitive upconversion nanocrystals-based sensor that instantaneously decomposes dynamic touch signals into normal and lateral shear force components from a single image. Mimicking human skin, the sensor generates axisymmetric luminescence for static normal forces and non-axisymmetric luminescence for dynamic shear forces. It demonstrates high spatiotemporal resolution for object screening and fingerprint recognition, enabling applications in Braille-to-speech translation and handwriting biometric recognition.

Changil Son, Jinyoung Kim, Dongwon Kang, Seojoung Park, Chaeyeong Ryu, Dahye Baek, Geonyoung Jeong, Sanggyun Jeong, Seonghyeon Ahn, Chanoong Lim, Yundon Jeong, Jeongin Eom, Jung-Hoon Park, Dong Woog Lee, Donghyuk Kim, Jungwook Kim, Hyunhyub Ko, Jiseok Lee