A Self-Powered Herbicide Sensing System Based on an Enzyme Biofuel Cell Integrated with Algal Cells

A screen-printed self-powered biosensor was developed to evaluate water toxicity. The biosensor consists of four photosynthetic microbial fuel cells connected in series and an LED indicator light. The bioanode is a screen-printed porous carbon electrode with an immobilized mediator and glucose oxidase, while the biocathode is a screen-printed porous carbon electrode with immobilized bilirubin oxidase and a screen-printed algal layer consisting of microalga Chlorella vulgaris embedded in alginate gel. Both the biocathode and fuel cell are light-responsive and atrazine-sensitive. The biocathode response is concentration-dependent up to 12 µM (M = mol dm−3) atrazine. The maximal power output of the fuel cell is 23.6 µW cm−2 under light irradiation. With a response time of 6 min, the self-powered biosensor is suitable as a rapid-response water toxicity monitoring system.