Microbial fuel cells for in-field water quality monitoring

Abstract

The need for water security pushes for the development of sensing technologies that allow online and real-time assessments and are capable of autonomous and stable long-term operation in the field. In this context, Microbial Fuel Cell (MFC) based biosensors have shown great potential due to cost-effectiveness, simplicity of operation, robustness and the possibility of self-powered applications. This review focuses on the progress of the technology in real scenarios and in-field applications and discusses the technological bottlenecks that must be overcome for its success. An overview of the most relevant findings and challenges of MFC sensors for practical implementation is provided. First, performance indicators for in-field applications, which may diverge from lab-based only studies, are defined. Progress on MFC designs for off-grid monitoring of water quality is then presented with a focus on solutions that enhance robustness and long-term stability. Finally, calibration methods and detection algorithms for applications in real scenarios are discussed.

Fig. 1. Principles of operation of an MFC sensor. In the presence of a disturbance, which could be for example the presence of a bioactive compound (the toxicant), a change in the electrical response is recorded. The biofilm is the sensing element (the bioreceptor) and the electrode is the transducer.

Fig. 2. Paper based MFC designs. (A) Membrane-based online sticker for wastewater monitoring. (B) Screen printed biosensor for toxicity detection in water.(C) Paper MFC sensor with conductive reservoir for bacterial attachment.

Fig. 3. Examples of sediment MFCs. (A). Monitoring of microbial activity for uranium remediation. (B) Detection of Cu²⁺; (C) sediment bulking sensor.

Fig. 4. Sediment MFCs for DO monitoring. (A) Monitoring of DO in a water column of a shallow lake with a sediment MFC with vertical cathode array; (B) multi-cathode SMFC deployed in an eutrophic bay.

Fig. 5. Field biosensors based on floating MFC; (A) detection of urine in water with a beacon Early Warning System; (B) detection of metals in river water; (C) sludge monitoring with floating boats (left) and flat floating MFC (right);(D) monitoring of oil spillages. (E) Dissolved oxygen monitoring with ceramic soil MFCs.