Electrodeposited CuO thin film for wide linear range photoelectrochemical glucose sensing

Cupric oxide (CuO) has been used as a non-enzymatic glucose sensor for decades. However, there is a paucity of publications on bare CuO-based photo electrochemical (PEC) glucose detection. In this study, a photo active CuO thin film was electrodeposited onto conductive glass and its band gap was tuned by etching in NH3 solution. A 6 W light-emitting diode (LED) bulb was used as the light source for PEC glucose oxidation. Various physical and electrochemical characterization techniques were used to study the PEC behavior of the CuO thin film electrode during glucose oxidation. The electrochemical oxidation of glucose was found to be an irreversible electron transfer process controlled by diffusion at the electrode surface under illumination and dark conditions. Electrochemical impedance spectroscopy (EIS) confirmed that the charge transfer resistance in the light decreases by several orders of magnitude. Good amperometric performance was obtained for the CuO film with a 4 s response time and negligible interference from other species present in human blood. The as prepared sensor exhibited a remarkable wide linear range up-to 29 mM.