Stretchable, stable and high-performance optoelectronic sensors based on hydrogel for ultraviolet imaging and wireless alarm

Flexible and wearable ultraviolet (UV) detectors have received widespread attention in the fields of personal UV exposure monitoring, intelligent bionic eyes and military. However, the non-stretchability of traditional materials and device structure design limits the precise monitoring and stable attachment of devices on dynamically deformable human skin and nonplanar surfaces. Here, intrinsically stretchable (up to 150% tensile strain or bending) UV detectors based on a novel strain-isolated heterojunction structure of CuO/carbon-hydrogel-ZnO/carbon have been proposed, exhibiting high sensitivity (on/off ratio of 2100%), high stability (>4000 cycles) and fast response and recovery time (1.5 and 4 s, respectively). Notably, the introduction of a p-n-junction-like band structure between CuO/carbon and ZnO/carbon electrodes with hydrogel bridge and the electrochemical reaction mechanism of I⁻/I₃⁻ in the ion-conductive hydrogel enhance the carrier efficiency and UV response intensity. A wireless UV alarm system is further developed by integrating the sensor with the designed circuit board for excessive UV intensity alarm. An optoelectronic sensor array is also designed and employed as a retinal prosthesis to realize real-time monitoring of environmental UV intensity and imaging functions. This work provides a promising approach to develop wearable and stretchable photoelectric UV sensor units and imaging arrays with hydrogel-based heterostructures. (Figure presented.)