Novel Applications of Microbial Fuel Cells in Sensors and Biosensors (original) (raw)
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Fuel, 2019
Microbial Fuel Cell (MFC) technology is a promising sustainable energy alternative to combat issues pertaining to non-renewable energy consumption, climate change, and environmental pollution. MFC technology employs anaerobic microorganisms, which convert biodegradable substances into simpler substances and produce bioelectricity. MFCs show promise for low-cost energy yielding wastewater treatment. Recent research efforts have shown that the technological know-how of MFC technology has evolved beyond the primary applications of wastewater treatment and energy generation. Hence, research attention has shifted towards other specific valueadded applications of MFCs such as small implantable health devices, robotics, and environmental quality monitoring sensors, etc. This article concisely addresses the potential applications of MFC technology past power production and wastewater treatment for biofuels such as biogas, and hydrogen production, and in the fields of medical implantable devices, robotics, and as biosensors for heavy metals and detection of toxic chemicals among others.
Biosensoric potential of microbial fuel cells
Applied microbiology and biotechnology, 2016
Recent progress in microbial fuel cell (MFC) technology has highlighted the potential of these devices to be used as biosensors. The advantages of MFC-based biosensors are that they are phenotypic and can function in either assay- or flow-through formats. These features make them appropriate for contiguous on-line monitoring in laboratories and for in-field applications. The selectivity of an MFC biosensor depends on the applied microorganisms in the anodic compartment where electron transfer (ET) between the artificial surface (anode) and bacterium occurs. This process strongly determines the internal resistance of the sensoric system and thus influences signal outcome and response time. Despite their beneficial characteristics, the number of MFC-based biosensoric applications has been limited until now. The aim of this mini-review is to turn attention to the biosensoric potential of MFCs by summarizing ET mechanisms on which recently established and future sensoric devices are based.
Optimization of the electrical signal generation of a microbial fuel cell for sensor applications
Vietnam Journal of Science, Technology and Engineering, 2020
In previous studies, a microbial fuel cell (MFC) was developed as a potential sensor that detects iron in water. However, to realize such an application in practice, the electrical signal generation of the MFC must be improved. Therefore, in this study, we investigated several measures to optimize the electrical signals of the MFC including (i) changing the anode spacing, (ii) testing different oxygen supply rates, (iii) testing different external resistances, and (iv) testing a new electrode material. An anode spacing of 2 cm was found to be optimal as the MFC generated a current that was at least 2-fold higher than any other anode spacing investigated. To limit oxygen diffusion from the cathode to the anode, an optimal cathode air flow rate of 1.8 ml min-1 was found, which corresponds to an oxygen supply rate of 0.286 mg min-1. By a polarization experiment, a 60-Ω external resistance ensured the most stable MFC-generated current , which is compulsory for the use of the device as a biosensor. Finally, activated carbon was shown to be an excellent material to improve electrical signal generation by 2-fold in comparison with graphite felt and graphite granules. These reported results will be the basis of further development of the MFC toward a practical biosensor.
Development of microbial fuel cell as biosensor for detection of organic matter of wastewater
The removal of biodegradable organic matters (BOM) is a very important aspect of evaluating the treatment efficiency in a wastewater treatment plant. However, conventional Biochemical Oxygen Demand (BOD) method is time consuming (3 or 5 days) and not suitable for online process monitoring. Instead biosensors can be used to measure BOD. Microbial Fuel Cell (MFC) biosensor which uses electroactive biofilms as sensing element has the advantage of long-term stability and minimizes the replacement of sensing elements. BOM could be directly converted to electricity via MFC, where MFC itself is an integration of signal generator and transducer. Proton Exchange Membrane (PEM) is a very important component of MFC and the most widely used Nafion PEM (NPEM) is costly . Previously, researchers have successfully used low cost clayware separators as PEM (CWPEM) with improved performance of MFC . Comparative studies has been carried out between MFC-1 (NPEM) and MFC-2 (CWPEM) to evaluate the performance of MFC as biosensor using mixed anaerobic culture with synthetic wastewater containing acetate as source of carbon. MFC-1 biosensor responds linearly between COD (Chemical Oxygen Demand) concentration of 22 mg/L and 51 mg/L (R 2 =0.954) with a response time between 120 min and 210 min. Similarly, MFC-2 biosensor responds linearly between a concentration 64 mg/L and 212 mg/L (R 2 =0.949) with a response time between 310 min and 120 min. The variation in rate of proton conductivity (PC) and thickness of the separators is suspected to be the cause for variation in range of detection and response time. The current market price of NPEM is very high i.e. Rs. 4000/10 cm 2 and that of CWPEM is Rs. 4/10 cm 2 . With improvement in PC of CWPEM, low cost MFC biosensor can be successfully developed. Once successfully developed, such low cost MFC based sensors can be calibrated for BOD.
International Journal of Electrochemical Science, 2017
The standard 5-days biochemical oxygen demand (BOD) method used for determination of biologically oxidizable organic material in wastewater considered to be laborious, time consuming and costly. Mediator-less microbial fuel cell (MFC) based biosensor offers an efficient alternative approach for real time monitoring of biodegradable organic matter in wastewater. Here we constructed an Hshaped MFC biosensor for comparing the efficiency of a complex natural (activated sludge) and artificially designed bacterial (Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus circulans) consortia as biological sensing elements for BOD measurements. Initially, the MFC biosensor was optimized and calibrated at pH 7 and temperature 37 o C using 100 mM phosphate buffer with 100 mM NaCl solution as catholyte at 10 kΩ external resistance. Maximum power density of 14.2 mW/cm 2 was generated by MFC-I with sludge consortium and it was 5 folds higher than MFC-II with artificial consortium. Standard glucose and glutamic acid (GGA) solutions were used for establishing the calibration curves between different BOD concentrations (50-250 mg/L) and voltage (mV) outputs in MFC. The regression equations for MFC-I and MFC-II biosensors were recorded as y 1 = 0.7834x-11.638 and y 2 = 0.1667x + 0.8476 respectively. Linear regression analysis revealed that 1 unit (mg/L) increase in organic load caused a voltage increase of 0.78 mV and 0.16 mV in the MFCs (I and II) reactors respectively. The relative performance in terms of stability (55-60 days) and reproducibility (within ±15.4%) of MFC-I BOD biosensor was almost double than MFC-II. The varying low concentrations of different electron acceptors (phosphate, nitrate and nitrite) in anodic compartments did not affect the performance of MFC biosensors.
Bioelectrochemistry, 2010
A MFC-based biosensor can act as online toxicity sensor. Electrical current is a direct linear measure for metabolic activity of electrochemically active microorganisms. Microorganisms gain energy from anodic overpotential and current strongly depends on anodic overpotential. Therefore control of anodic overpotential is necessary to detect toxic events and prevent false positive alarms. Anodic overpotential and thus current is influenced by anode potential, pH, substrate and bicarbonate concentrations. In terms of overpotential all factor showed a comparable effect, anode potential 1.2% change in current density per mV, pH 0.43%/mV, bicarbonate 0.75%/mV and acetate 0.8%/mV. At acetate saturation the maximum acetate conversion rate is reached and with that a constant bicarbonate concentration. Control of acetate and bicarbonate concentration can be less strict than control of anode potential and pH. Current density changes due to changing anode potential and pH are in the same order of magnitude as changes due to toxicity. Strict control of pH and anode potential in a small range is required. The importance of anodic overpotential control for detection of toxic compounds is shown. To reach a stable baseline current under nontoxic conditions a MFC-based biosensor should be operated at controlled anode potential, controlled pH and saturated substrate concentrations.
Microbial fuel cell biosensor for in situ assessment of microbial activity
Biosensors and Bioelectronics, 2008
Microbial fuel cell (MFC)-based sensing was explored to provide useful information for the development of an approach to in situ monitoring of substrate concentration and microbial respiration rate. The ability of a MFC to provide meaningful information about in situ microbial respiration and analyte concentration was examined in column systems, where Geobacter sulfurreducens used an external electron acceptor (an electrode) to metabolize acetate. Column systems inoculated with G. sulfurreducens were operated with influent media at varying concentrations of acetate and monitored for current generation. Current generation was mirrored by bulk phase acetate concentration, and a correlation (R 2 = 0.92) was developed between current values (0-0.30 mA) and acetate concentrations (0-2.3 mM). The MFC-system was also exposed to shock loading (pulses of oxygen), after which electricity production resumed immediately after media flow recommenced, underlining the resilience of the system and allowing for additional sensing capacity. Thus, the electrical signal produced by the MFC-system provided real-time data for electron donor availability and biological activity. These results have practical implications for development of a biosensor for inexpensive real-time monitoring of in situ bioremediation processes, where MFC technology provides information on the rate and nature of biodegradation processes.
Electrical Characterization of Microbial Fuel Cells – Method and Preliminary Results
2019
Microbial fuel cells (MFC) present bioelectrochemical systems that allow generation of electricity during anaerobic respiration of selected bacterial species. They have very promising applications in wastewater purification systems, as biosensors or as alternative power source. This work is a result of joint multidisciplinary research and presents preliminary experimental results obtained by electrical characterization of a single-chamber MFC. The goal of research was to study activity of MFC and estimate its internal resistance.
A novel minimally invasive method for monitoring oxygen in microbial fuel cells
Biotechnology Letters, 2012
Oxygen availability is a potential ratelimiting step in the bioelectrochemical process catalyzed by microbes in microbial fuel cells (MFC). Determination of oxygen availability using a minimally invasive oxygen sensor is advantageous in terms of ease of usage, maintenance and cost-effectiveness as compared to using conventional probe-type oxygen sensors. The utility of this method is substantiated by using this sensor to demonstrate the relationship between oxygen availability and current density. 10 % drop in oxygen concentration resulted in a concomitant drop in current density by about 36 %, further establishing the criticality of monitoring oxygen levels in the MFC. The detachable sensor membrane of the minimally invasive sensor confers multiple advantages. The novel method would enable real-time monitoring of oxygen in MFCs, simplify process optimization and validation and more importantly, provide an impetus for development of more efficient MFC designs.
In situ microbial fuel cell-based biosensor for organic carbon
Bioelectrochemistry, 2011
The biological oxygen demand (BOD) may be the most used test to assess the amount of pollutant organic matter in water; however, it is time and labor consuming, and is done ex-situ. A BOD biosensor based on the microbial fuel cell principle was tested for online and in situ monitoring of biodegradable organic content of domestic wastewater. A stable current density of 282 ± 23 mA/m 2 was obtained with domestic wastewater containing a BOD 5 of 317 ± 15 mg O 2 /L at 22 ± 2°C, 1.53 ± 0.04 mS/cm and pH 6.9 ± 0.1. The current density showed a linear relationship with BOD 5 concentration ranging from 17 ± 0.5 mg O 2 /L to 78 ± 7.6 mg O 2 /L. The current generation from the BOD biosensor was dependent on the measurement conditions such as temperature, conductivity, and pH. Thus, a correction factor should be applied to measurements done under different environmental conditions from the ones used in the calibration. These results provide useful information for the development of a biosensor for real-time in situ monitoring of wastewater quality.