Flexible hydrogel laser textile for multifunctional sensing

Flexible optical sensing systems have evolved into a promising frontier for personalized health monitoring, leveraging their non-invasive operation and continuous data acquisition. Nevertheless, current optical solutions remain constrained by limitations in detection sensitivity and specificity, hindering its reliability in dynamic clinical environments. Herein, we propose a design of flexible semi-interpenetrating network hydrogel lasing textiles for multifunctional sensing, including relative humidity and acid pH detection. By integrating the humidity-responsive swelling and carboxyl protonation-mediated optical loss modulation of hydrogels with whispering-gallery-mode microcavity lasers, we achieve a dual-parameter flexible optical sensing based on wavelength shift and spectral linewidth modulation, enabling a 227 pm/%RH sensitivity of humidity detection and 125 pm/pH sensitivity of acid pH monitoring, with limit of detection of 0.71 %RH and 0.55 pH, respectively. This work is expected to establish new pathways for non-invasive health monitoring in flexible systems.