Generating Electricity on Chips: Microfluidic Biofuel Cells in Perspective

Microfluidic electrochemical energy systems precisely manipulate the fluid flow pattern in microfluidic channel to generate electrical energy without the need to use physical barriers such as proton-exchange membranes that other fuel cells normally do. Among various microfluidic devices, microfluidic biofuel cells combine the microfluidic technology with biocatalysts (e.g., enzyme and bacteria), representing an emerging membrane-free power generator. In this work, we first present an overview of the recent progress made for microfluidic biofuel cells, including the understanding of fundamental working principles, the designs of state-of-the-art devices, and the solutions to substantial challenges in further refining the technique. Key factors to improve power output, the scaling-up process, and the design of novel-architecture electrodes are thoroughly discussed. At last, we propose potential opportunities and discuss their advantages associated with microfluidic biofuel cells as power sources for miniature electronics, in vivo sensors, and total bioanalysis systems.