Recent Advances in ZnO Based Electrochemical Ethylene Gas Sensors for Evaluation of Fruit Maturity

India is the largest producer of fruits and vegetables in the world. However, a major portion of agro-products is wasted during harvesting, shipping, and storage, i.e., negligence in the food supply chain management (FSCM) system. Globally, one third of food produced is wasted. Importantly, two-third of the wastage of food occurs due to limitations in the supply chain management system. Wastage of perishable agro-products due to negligence in FSCM is a critical issue, especially in the case of agro-products like fruit. Therefore, the early detection and segregation of fruits are critical to reduce agro-product wastage. A typical indicator of maturity and ripening of fruits is the rate of generation and concentration of ethylene gas. Even though, literature encompasses examples of a variety of ethylene gas sensors, ZnO based electrochemical ethylene gas sensors depict numerous advantages compared to other sensor variants. ZnO is an extensively studied wide band gap semiconductor for sensing applications. When used as a sensing layer material it ‘senses’, ethylene gas by changing its band gap and thereby electrical property. Further, the sensitivity and selectivity of the pristine ZnO vary with shape, substrate, and metal doping. This paper elucidates a review of recent advances in ZnO based electrochemical sensors for ethylene gas detection. The review covers various levels of design abstraction that include material and device. In addition, we summarize the design challenges and future trends in the development of ZnO based electrochemical ethylene gas sensors.