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 (Voc) depends solely on light intensity, whereas the short-circuit current (Isc) 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 Voc below 1.1% and a strain gauge factor of 0.44 derived from Isc. This approach addresses a key limitation of stretchable photodetectors and provides a pathway toward high-resolution, position-aware wearable optical biosensing.