Skin-Inspired Monolithic Multimodal Optical Fibers via Thermochromic Microcapsule-Doped Elastomers

Inspired by human skin, we developed a monolithic POF sensor for temperature, pressure, and bending. Red, yellow, and green thermochromic microcapsules were embedded in a PDMS matrix. Temperature was detected through wavelength-selective absorption, with a maximum sensitivity of 9.28%/°C. Pressure and bending were measured through deformation-induced radiation loss and macrobending loss, with sensitivities of 116.83%/mm and 0.48%/deg, respectively. Temperature and mechanical signals exhibit two distinct spectral responses: wavelength-selective thermal modulation and broadband mechanical attenuation, respectively. Based on this spectral orthogonality, it is possible to effectively distinguish between the two at the physical level. Pressure and bending were separated using spatially distributed sensing channels. The fibers retained an elongation at break above 135% and operated over bending angles from 0° to 90°. Integration into a smart glove enabled simultaneous recognition of joint movement, relative grip pressure, and object temperature. This design provides an all-optical approach to multimodal sensing in wearable devices and human-machine interfaces.