Optical-based stretchable multimodal sensors for detecting strain and light with periodic buckling structures

Stretchable optoelectronic sensors are essential for next-generation wearable health monitoring; however, a critical limitation remains unresolved. When a stretchable photodetector deforms, the effective light-detection location shifts across the skin surface, complicating the interpretation of spatially localized physiological signals. Herein, we report a periodic-buckling stretchable organic photodetector (OPD) that enables dual optical and strain sensing within a single device, allowing real-time estimation of changes in the effective detection position. The open-circuit voltage (V_oc) depends solely on light intensity, whereas the short-circuit current (I_sc) reflects both light intensity and variations in the active area, enabling geometric localization of the photodetection site. The OPD exhibits stable performance under applied strains of up to 60%, with variations in V_oc below 1.1% and a strain gauge factor of 0.44 derived from I_sc. This approach addresses a key limitation of stretchable photodetectors and provides a pathway toward high-resolution, position-aware wearable optical biosensing.