Enzymatic Oxygen Microsensor Based on Bilirubin Oxidase Applied to Microbial Fuel Cells Analysis

A selective oxygen biosensor based on bilirubin oxidase (BOx) was developed. The sensor was used for determining oxygen profiles in a membraneless, single-chamber microbial fuel cell (SCMFC), fed with raw wastewater. The linear response of the sensor was optimized by a diffusion layer of silica gel. A computer-controlled stage was used to obtain accurate and precise measurements. Oxygen concentration in biofilms covering electrodes was measured, showing 3 mg L−1 of O2 in the bulk solution, decreasing to 0 mg L−1 in the cathodic biofilm. The MFC generated power in the range of 0–0.08 mW, associated to the oxygen content.