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 mm²) and an 8 × 8 multipixel array (100 × 100 mm²) 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.