Microbial fuel cell (MFC) technology directly converts chemical energy contained in organic matter into electricity through the metabolic processes of microorganisms and it is shown to be promising to assess the quality of water. The development of a biofilm consisting of an electroactive bacteria on the surface of the anode is capable of transferring electrons generated from the oxidation of organic compounds to the electrode. Thus, the current generated by the MFC can be correlated to the metabolic activity of the anodic bacteria and any possible disturbances to its metabolic pathways, caused by environmental changes, such as organic load, or due to the presence of toxic compound(s), is likely to be reflected in the measured current. In spite of their ability, implementation of MFCs as sensors is limited by device designs and high cost involved in the fabrication process. Researchers at University of Bath, United Kingdom have developed a simple and cost-effective single-component paper-based MFC (pMFC) sensor device by screen printing carbon-based electrodes onto a single sheet of paper (Jon Chouler et al., Biosensors and Bioelectronics, 102 (2018) 49-56).
The paper-based MFCs (pMFC) sensor was fabricated by screen-printing. The conductive ink contains a solution mixture with 20 mg α-cellulose dissolved in 1-ethyl-3-methylimidazolium and dimethyl sulfoxide with 92:8% w/w ratio in which 40 mg carbon nanofibers and 40 mg graphite powder were thoroughly dispersed. Three layers of the conductive ink were screen-printed (43–80 μm mesh) onto the paper to form the electrodes (Fig. 1). Since the paper substrate itself acts as the separator between the two electrodes, the cellulose fibers within the paper were cross-linked with glyoxal (0-24% w/v at 20 °C for 3 h), which helped to increase robustness and operational lifetime of the sensor device. The electrochemical performance of the paper-MFC sensor for detecting formaldehyde, a potential toxic compound, was evaluated. Two pMFCs were folded back-to-back to fabricate fpMFC which enriched the performance of the sensor device. Portability, facile use, and biodegradability are the unique advantages of this paper-based MFC sensor.
Fig. 1 (a) Schematic of the pMFC and electrical connection; (b) Photograph of the actual pMFC, showing size; (c) Principle of operation of the pMFC; and (d) Assembly of the fpMFC by folding two pMFCs back-to-back (1), with parallel electrical connection (2).
T.S.N. Sankara Narayanan
For more information, the reader may kindly refer: Jon Chouler et al., Biosensors and Bioelectronics, 102 (2018) 49-56
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