A Multilayer Colorimetric Sponge Dressing with Unidirectional Exudate Drainage for Simultaneous Monitoring of pH and Moisture in Wound

Abstract Despite significant improvements in acute and chronic wound care, determining optimal timing for individualized dressing changes remains a critical clinical challenge, with a lack of objective and precise evaluation criteria. To meet this need, a multilayer colorimetric dressing is designed that integrates unidirectional exudate drainage, pH, and moisture monitoring. An ice‐templated polyurethane sponge featuring aligned microchannel structures is developed to achieve exudate drainage. The pH colorimetric module is fabricated by embedding phenol red indicator into hydrogel via solution diffusion, while the moisture colorimetric module incorporates carbon‐encapsulated Fe 3 O 4 (Fe 3 O 4 @C) nanoparticles doped photonic crystal hydrogel. This dressing overcomes the key limitations of traditional electrochemical sensors, which require wired connections and power source, by employing visible light‐based colorimetric analysis with RGB quantification. The dressing achieves a unidirectional exudate drainage rate of 2.35 µL s −1 , with a pH monitoring range of 5.0–8.0 and a humidity detection range of 11–100%. Proof‐of‐concept studies conducted both in vitro and in infected rat models validate the capability of the dressing for real‐time monitoring of wound microenvironment pH and humidity levels. This innovative technology offers a clinically viable approach to determine optimal dressing change frequency, thereby enhancing healing outcomes while minimizing infection risks.