Microbial Fuel Cell-Based Sensors

Dear Colleagues,

Microbial fuel cells (MFCs) are intriguing bio-devices that are able to directly convert the chemical energy embedded in organic matter into electrical energy by exploiting the great potential of exoelectrogenic bacteria. This kind of bacteria are, indeed, able to catalyze the oxidation reaction of organic matter, releasing the produced electrons directly to an electrode surface. Due to this property, MFCs have gained popularity during the last years.

When used as energy harvesters, MFCs have the unique ability to work without the need for any additional power input and with very limited maintenance, making them particularly suitable for application in remote areas. Moreover, since output electricity is directly related to the metabolism of microorganisms in the biofilm, they spontaneously adapt the efficiency of the chemical energy conversion as a response to the main environmental conditions. This makes MFCs inherently capable of working as biosensors. In MFC-based biosensors, the output current can be considered the electrical signal generated by the MFC itself as a response to the input chemical signal (i.e., the chemical energy of the substrate). The conversion of the chemical signal into the electrical current is performed by the anodic electrode, which acts as the sole transducer.

Interestingly, if the bio-devices are kept in unsaturated-fuel conditions, with the other parameters being at constant values, variations in the fuel (i.e., substrate) concentration directly cause changes to the current generated by the anodic biofilm during substrate oxidation. Moreover, toxicants can be detected if interacting with the biofilm: Indeed, their presence can be revealed as a change in the number of electrons generated by the MFC, correlated with a change of the output current intensity. This is the working principle of MFCs as an intriguing class of amperometric biosensors, for real-time, in situ monitoring of water quality.

MFC-based biosensors are demonstrating great potential for practical use and attracting increasing interest. Work is needed to further increase their sensitivity, reduce detection time, and improve usability through a simple but effective design.

Several factors affect the behavior of MFC-based sensors. First of all, the biofilm, working as the receptor, is the key element of the sensor: Mixed population biofilms seem to be promising to gain sensitivity for a wide range of analytes. Actually, to properly perform the detection, the biofilm has to be intimately connected to the anodic material, acting as the transducer in MFC-based sensors. The electrode has to be conductive, and both its surface chemistry and morphology have to be carefully designed, thus employing/improving biofilm growth and adhesion. Indeed, the complex interface formed at the biofilm/anode junction plays a fundamental role in determining the behavior and performance of the MFC-based biosensor. The architecture of the device can also deeply influence the detection capabilities of the systems. Advancements in reactor optimization can be performed in terms of their size, shape, and arrangement, but also exploiting the potential of different and new technological approaches. Finally, multiphysics modeling is an important tool that could help to predict mechanisms and reactions occurring in the systems that cannot be easily evaluated experimentally and so drive the design of the reactors.

The Special Issue “Microbial Fuel Cell-Based Sensors” aims to summarize the state of the art of the research and the technological advancement on MFC-based biosensors. The Special Issue includes but is not limited to the following topics:

• Biofilms for sensing;
• Biofilm/anode interface analysis;
• Anodic materials;
• Electrode design;
• Reactor design;
• New technological approaches;
• Miniaturization;
• Microfluidic approaches;
• Multiphysics modeling;
• Water biosensors;
• Sediments and soils sensing.

Original research papers or review articles are welcome in this Special Issue. Emphasis will be given to experimental analysis both at lab scale as well as practical, in situ applications. Fundamental studies in line with the scope of this Special Issue can also be considered for publication.

Sincerely,

Dr. Fabrizio Pirri
Dr. Marzia Quaglio
Dr. Giulia Massaglia
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• Microbial fuel cell (MFC)-based sensors
• Bioelectrochemical sensors
• Nicrofluidic MFC-based sensors
• Miniaturized MFC-based sensors
• Design of MFC-based sensors
• MFC modeling
• Biofilm/anode interface
• Anodic materials for MFC-based sensors
• Water quality monitoring
• Soil quality sensing