A Quasi Solid-State Hydrogel/InGaN Nanorod Heterostructure-Enabled Amphibious Sensor for Stable and Cross-Medium Optical Sensing and Monitoring.

The wearable optoelectronic systems, often employed with miniaturized and portable photosensors, can be conformably integrated with the human body to promote the advancement of health monitoring and protection. However, developing advanced photosensors with a simple structure that can be sustainable with high sensitivity in different operation conditions, e.g., cross-medium amphibious (terrestrial/aquatic environments) photosensing to match the diverse and complex human activities remains limited. Here, we propose a self-powered photoelectrochemical-type photosensor composed of a hydrogel/InGaN nanorod heterostructure to mimic amphibious biophotosensory behavior. Strikingly, the ion-conductive quasi solid-state hydrogel enables the device to execute cross-medium photoresponse, maintaining consistent photoresponsive metrics under both terrestrial and submerged conditions. More importantly, by simply tailoring the bandgap of InGaN nanorods followed by a facile carbon-layer passivation strategy, we achieve high-selectivity harmful wavelength (280-420 nm) detection under sunlight and an impressive ultraviolet responsivity (130.7 mA/W) with fast response speed (<10 ms). A proof-of-concept demonstration of amphibious-type ultraviolet sensing system exhibits a stable operation in waterfront environments, achieving real-time monitoring and analysis of ultraviolet intensity on land and underwater across various weather conditions. This work provides a practical and reliable device platform for the development of multifunctional optoelectronic systems in the pursuit of wearable amphibious-type photosensors for complex environment monitoring.