Scalable Photonic Crystal Sensors and Arrays Integrating Power‐Free Display Interface With Dual‐Mode Optical/Electrical Feedback for Real‐Time Physiological Analysis

Abstract Photonic crystal (PC) hydrogel‐based sensors with visual signal outputs have attracted attention for wearable motion monitoring, but current devices suffer from low spatial resolution, small‐scale design, and poor signal consistency. Herein, we present a combined and scalable PC sensing platform that includes a single‐point sensor (100 × 400 mm ² ) and an 8 × 8 multipixel array (100 × 100 mm ² ) for dual‐mode visual‐electrical feedback. The array achieves 2D strain mapping on the arm with a spatial resolution of 0.33 mm ⁻¹ and uniform color difference (ΔE < 6), while the single sensor enables wireless monitoring of full‐body motion. The sensors exhibit mechanochromic sensitivity up to 7.78 nm·% ⁻¹ and a gauge factor of 1.21. In addition, the hydrogel matrix provides excellent mechanical performance, supporting long‐term signal consistency. By integrating a pixelated PC sensor array for localized joint analysis with a scalable single‐point sensor for full‐body motion tracking, the system enables multiscale monitoring of human activity. This combination offers improved adaptability for complex gait recognition, early‐stage diagnostics, and energy‐efficient wearable health monitoring.