A biodegradable, flexible photonic patch for in vivo phototherapy

Diagnostic and therapeutic illumination on internal organs and tissues often lacks controllability over spectrum, area, depth, and intensity. The authors present a flexible, biodegradable photonic device (iCarP) comprising a removable tapered optical fiber (TOF) embedded parallel to tissue within a transparent polyester (PMCL) patch, separated by a micrometer-scale air gap. Diffraction at the TOF tip, dual refractions at the TOF/air and air/PMCL interfaces, and reflection within the patch transform forward-directed light into a bulb-like, laterally guided illumination. iCarP achieves large-area, high-intensity, wide-spectrum, continuous or pulsatile, deeply penetrating illumination without puncturing target tissue and supports multiple phototherapies. The device is compatible with thoracoscopic minimally invasive implantation on beating hearts, indicating a safe, precise, and broadly applicable platform for internal tissue illumination, diagnosis, and therapy.