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Decoupling dynamic touch signals in the optical tactile sensors is highly desired for behavioral tactile applications yet challenging because typical optical sensors mostly measure only static normal force and use imprecise multi-image averaging for dynamic force sensing. Here, we report a highly sensitive upconversion nanocrystals-based behavioral biometric optical tactile sensor that instantaneously and quantitatively decomposes dynamic touch signals into individual components of vertical normal and lateral shear force from a single image in real-time. By mimicking the sensory architecture of human skin, the unique luminescence signal obtained is axisymmetric for static normal forces and non-axisymmetric for dynamic shear forces. Our sensor demonstrates high spatio-temporal screening of small objects and recognizes fingerprints for authentication with high spatial-temporal resolution. Using a dynamic force discrimination machine learning framework, we realized a Braille-to-Speech translation system and a next-generation dynamic biometric recognition system for handwriting. A sensitive upconversion nanocrystal-based biometric optical tactile sensor instantaneously and quantitatively decomposes dynamic touch signals into individual components of vertical normal and lateral shear force from a single image in real-time.

Polymeric materials have been used to realize optical systems that, through periodic variations of their structural or optical properties, interact with light-generating holographic signals. Complex holographic systems can also be dynamically controlled through exposure to external stimuli, yet they usually contain only a single type of holographic mode. Here, we report a conjugated organogel that reversibly displays three modes of holograms in a single architecture. Using dithering mask lithography, we realized two-dimensional patterns with varying cross-linking densities on a conjugated polydiacetylene. In protic solvents, the organogel contracts anisotropically to develop optical and structural heterogeneities along the third dimension, displaying holograms in the form of three-dimensional full parallax signals, both in fluorescence and bright-field microscopy imaging. In aprotic solvents, these heterogeneities diminish as organogels expand, recovering the two-dimensional periodicity to display a third hologram mode based on iridescent structural colours. Our study presents a next-generation hologram manufacturing method for multilevel encryption technologies. Periodic patterns with varying cross-linking densities are realized in conjugated polydiacetylene films, creating multiple holographic images—all dynamically responsive to exposure to various solvents—simultaneously in the same polymeric structures.