Elastic Janus Microarray Film Strain Sensors with Heterogeneous Modulus and Conductivity for Healthcare and Braille Identification

Most stretchable film strain sensors generally present nonlinear electrical responses to applied strain, leading to an inaccurate acquisition of sophisticated signals, difficult signal processing, and zero-calibration, which hampers practical applications severely. Here, a Janus hetero-structured microarray film sensor is developed by in-situ growth of silver nanoparticles on the surface of micro-patterned elastomer films fabricated via low-temperature imprinting followed by scraping-induced particle trapping. Heterogeneous property designs in both modulus and electrical conductivity via introducing polymer microarrays enable modulating the electron transport manner in the conductive layer of elastic Janus films upon stretching, allowing to tune signal linearity effectively. Therefore, such a hetero-structured film sensor shows good signal linearity (fluctuation of gauge factor [GF] below +/- 0.02) and relatively high sensitivity (GF > 10) within 55% strain, a detection limit of 0.2% strain, and a response/recovery time of 16.3/46.9 ms, respectively. Correspondingly, it enables monitoring human respiration and body motion with higher resolution compared with the nonlinear one, meanwhile, it is capable of detecting tiny pressure to discriminate braille alphabets via touch identification. Overall, it unveils a simple strategy to fabricate film strain sensors for high-resolution healthcare and body motion monitoring, as well as electronic skins toward tactile sensing and tough identification.