Simulation for regulatable assembly of large-scale photonic crystal: Application in flexible pressure sensor with visual sensing

Photonic crystal (PC) sensors have attracted increasing attention for their visual signal output. However, their applications are hindered by the small-scale, defective arrays, and the time-consuming self-assembly. Herein, an efficient self-skinning method for regulating assembly of polystyrene (PS) microspheres and a large-scale PC sensor have been developed. The flowability and rapid reconfigurability of pre-crystallized PS dispersions were investigated through numerical simulation, allowing for control of the assembly through the colloid skin. The simulation and SEM characterization verify that the regulation of colloid skin suppresses the uneven evaporation flux and thus the large-scale and crack-free PC arrays (100 × 400 mm 2 ) are fabricated within 150 s. The PC sensor shows reversible visual signal output with mechanochromic sensitivity of 4.95–12.1 nm∙kPa −1 . The scalable PC sensor achieves sensitive-monitoring of human plantar pressure through visual signal output, suggesting a promising potential in gait recognition, health analysis, and so on.