Self-Powered Flexible Edible UV Sensors Based on Sustainable Materials Applicable for Food Packaging

In this letter, we present a novel self-powered ultraviolet (UV) sensor using edible materials for food packaging applications. As urbanization takes place on a global scale, the general public's reliance on packaged food increases rapidly. To reduce food loss in the supply chain, environmental conditions where food products are exposed need to be monitored carefully. UV light can induce chemical changes in perishable foods, and UV sensors can detect such changes to warn of potential food spoilage, ensuring food safety for consumers. Most of the developed UV sensors are made of nonfood grade materials, which do not biodegrade and become another source of pollution if not disposed of properly. In addition, the dependence of sensors on external power sources limits their applicability in food packaging. We present a flexible UV sensor using a substrate of ethyl cellulose created by evaporating a solution of ethanol and ethyl cellulose. The sensor incorporates stacked interdigitated electrodes with an algae-based electrolyte and ZnO layer as the UV absorbent material, demonstrating the novel use of organic materials in UV detection. The fabricated device works in a photovoltaic mode; the results revealed that the sensor can detect UV changes without applying external bias under a 365-nm centered laser radiation.