Hydrocolloid-integrated organic optoelectronic patch for wearable wound phototheranostics

In this study, we developed a flexible wearable phototheranostic patch integrating a red organic light-emitting diode (OLED) and an organic photodiode (OPD) with a hydrocolloid dressing. The platform enables photobiomodulation (PBM) using a 630 nm red OLED together with photoplethysmographic (PPG) sensing through an adjacent OPD. The hydrocolloid provides low elastic modulus and high conformability while maintaining mechanical and optical stability under repeated bending. To coordinate optical therapy and sensing, the OLED was operated using pulse-width modulation (PWM) at 50 Hz with a 30 % duty cycle. PPG measurements showed that PWM maintained clear signal acquisition at reduced time-averaged irradiance, with SNR generally increasing as the PWM ON-state irradiance increased. Among the tested PWM conditions, PWM-16.67 exhibited the strongest overall cell-proliferative response and the highest SNR, while delivering approximately the same radiant exposure as the DC reference. Notably, PWM-10 also achieved a cell-proliferative response comparable to the DC reference while reducing radiant exposure by 40 %, indicating its potential as a lower-exposure operating condition. Thermal measurements further showed that PWM reduced heat accumulation relative to continuous DC operation at matched peak irradiance, although this thermal advantage was partially diminished as the higher ON-state current required for increased PWM irradiance introduced additional thermal load. These results demonstrate the feasibility of integrating optical therapy and physiological sensing within a single conformable hydrocolloid-based OLED–OPD platform and provide a basis for further development of wearable wound phototheranostic systems.