2.8.2 Biosensors
The IUPAC defined electrical biosensors as a self-contained integrated device
providing specific analytical information using a biological recognition element
(microbes) contacting with an electrochemical transduction element (anode and
cathode electrodes) (Sun et al. 2015; Dai and Choi 2013). Based on this definition,
the MFC system, which uses microorganisms as the recognition element in the
anodic compartment to directly and efficiently produce an electrical energy in
response to exogenously added analyte, could be considered as biosensors (Sun
et al. 2015). In addition, MFCs are able to act as power supplies for some small
devices such as sensors and biosensors, and also they themselves have the capability
of serving as biosensors. In comparison with traditional biosensors for online and
rapid monitoring of environmental parameters such as biological oxygen demand
(BOD), a total organic carbon (TOC) which requires an external power and a
transducer to convert measured signal to electrical signal MFC-based biosensors
does not need any external power supplies and transducer since the current output is
electrical by itself. These biosensors have many advantages such as long-term
stability, continuous monitoring, fast analyzing, being cost-effective, and being
able to be a safe power source (Kumlanghan et al. 2007).
For example, the MFC system can be used as an online biosensor for observing
metabolic activity of the microorganisms due to its online monitoring of current and
operating without a transducer to read the signal output and external power source. A
MFC with duration of about 5 years to produce stable current generation has been
demonstrated by Kim et al. By this demonstration, the strength of wastewater was
directly proportional to the coulomb generated from MFC, which provides the
opportunity to use it as a BOD biosensor (Kim et al. 2010). This is its unique
property, which facilitates the construction of portable and self-powered biosensors
based on MFC techniques in contrast with other types of online biosensors that often
need complex nonlinear transducers (Stein et al. 2010).
Several researchers have reported the use of MFC in BOD biosensor, since the
coulomb and current density generated by the MFC is directly proportional to the
BOD concentration and the strength of the wastewater (Kim et al. 2003).
As the MFC output mainly depends on the microbial activity and transfer rate of
electrons from the microorganisms to the anode surface, presence of toxic compounds which inhibited the microbial activity will decrease the MFC output compared to a situation without any toxicants. This means that the MFC is feasible to
serve as a sensor for monitoring of toxicity in water too (Sun et al. 2015; Stein et al.
2010).
Also, using MFC as a power supply in construction of a self-powered DNA
biosensor to identify genetic defects is another application of mentioned technology
which has the most novelty compared with other ones (Asghary et al. 2016).
9 Microbial Fuel Cell (MFC): An Innovative Technology for Wastewater. . .
227
The IUPAC defined electrical biosensors as a self-contained integrated device
providing specific analytical information using a biological recognition element
(microbes) contacting with an electrochemical transduction element (anode and
cathode electrodes) (Sun et al. 2015; Dai and Choi 2013). Based on this definition,
the MFC system, which uses microorganisms as the recognition element in the
anodic compartment to directly and efficiently produce an electrical energy in
response to exogenously added analyte, could be considered as biosensors (Sun
et al. 2015). In addition, MFCs are able to act as power supplies for some small
devices such as sensors and biosensors, and also they themselves have the capability
of serving as biosensors. In comparison with traditional biosensors for online and
rapid monitoring of environmental parameters such as biological oxygen demand
(BOD), a total organic carbon (TOC) which requires an external power and a
transducer to convert measured signal to electrical signal MFC-based biosensors
does not need any external power supplies and transducer since the current output is
electrical by itself. These biosensors have many advantages such as long-term
stability, continuous monitoring, fast analyzing, being cost-effective, and being
able to be a safe power source (Kumlanghan et al. 2007).
For example, the MFC system can be used as an online biosensor for observing
metabolic activity of the microorganisms due to its online monitoring of current and
operating without a transducer to read the signal output and external power source. A
MFC with duration of about 5 years to produce stable current generation has been
demonstrated by Kim et al. By this demonstration, the strength of wastewater was
directly proportional to the coulomb generated from MFC, which provides the
opportunity to use it as a BOD biosensor (Kim et al. 2010). This is its unique
property, which facilitates the construction of portable and self-powered biosensors
based on MFC techniques in contrast with other types of online biosensors that often
need complex nonlinear transducers (Stein et al. 2010).
Several researchers have reported the use of MFC in BOD biosensor, since the
coulomb and current density generated by the MFC is directly proportional to the
BOD concentration and the strength of the wastewater (Kim et al. 2003).
As the MFC output mainly depends on the microbial activity and transfer rate of
electrons from the microorganisms to the anode surface, presence of toxic compounds which inhibited the microbial activity will decrease the MFC output compared to a situation without any toxicants. This means that the MFC is feasible to
serve as a sensor for monitoring of toxicity in water too (Sun et al. 2015; Stein et al.
2010).
Also, using MFC as a power supply in construction of a self-powered DNA
biosensor to identify genetic defects is another application of mentioned technology
which has the most novelty compared with other ones (Asghary et al. 2016).
9 Microbial Fuel Cell (MFC): An Innovative Technology for Wastewater. . .
227