Biodegradable photonic crystal-embedded adhesive patch for visible surveillance of tissue regeneration

Skin is continuously exposed to chemical, physical, and biological threats, making it prone to injury and challenging to fully repair. During healing, dynamic metabolic changes influence epidermal regeneration, with local acidity reflecting inflammation or infection. Inspired by these physiological dynamics, we developed a biodegradable adhesive patch embedded with porous silicon-based photonic crystal (PC) sensors for visible monitoring of tissue regeneration. Fabricated via sinusoidal electrochemical etching, these PCs reflect visible light at specific wavelengths and exhibit acidity-sensitive degradation rates, degrading approximately four times faster in basic conditions. Color changes rapidly indicate inflammatory or infectious states. In vivo studies using lipopolysaccharide (LPS) and methicillin-resistant Staphylococcus aureus (MRSA) wound models demonstrated clear correlation between PC patch color shifts and inflammation severity. Thus, this biodegradable PC patch provides an intuitive, non-invasive tool for real-time wound monitoring, enabling prompt interventions and improved patient care.