Living Electroactive Microorganism-Based Biohybrid Microbial Fuel Cell Biosensor for Formaldehyde in Water Monitoring and Dose-Response Curve Determination

In this abstract, we present utilizing living electroactive microorganism-based biohybrid microbial fuel cell biosensor for formaldehyde in water monitoring and dose-response curve determination. We have built microfluidic MFCs with anode and cathode chambers of 100μL. Start-up process of the microfluidic MFC biosensor takes 3-5 days and we utilize the MFC biosensor for formaldehyde in water monitoring as well as determining the dose-response curve. It is found that when the MFC biosensor is exposed to a large formaldehyde concentration range from a low concentration of 1x10^-3 mg/L to a high concentration of 3 mg/L in water, a real-time current drop is observed after each formaldehyde injection, and a higher formaldehyde concentration results in a higher current drop percentage, which makes the biosensor suitable for measuring formaldehyde concentration. Analyzing the experimental results shows a sigmoid relationship between the output current and the formaldehyde concentration, and the experimental results are in agreement with traditional toxicology dose-response curve obtained by other measurement techniques.
Water pollution is a global health threat affecting 2 billion people, causing significant health issues. Traditional non-real-time methods are time-consuming and expensive. Therefore, a real-time and low-cost sensor for toxic chemical in water monitoring is needed. In addition, traditional dose-response curve determination methods are time-consuming and requires expensive equipment. In this abstract, we report utilizing living electroactive bacteria based microfluidic MFC biosensor as a low-cost and real-time platform to monitor toxic chemical concentration and determine dose-response curve.
The microfluidic MFC biosensor is composed of anode, cathode and proton exchange membrane (PEM) with a chamber volume of 100 μL. The anode/cathode are 100nm-thick Pt thin films deposited by magnetic sputtering. The start-up process of the MFC biosensor takes approximately 3-5 days. We perform polarization characterization, which shows that the MFC biosensor operates normally. Afterwards, we inject formaldehyde into the MFC biosensor to test the capability of the MFC biosensors for monitoring formaldehyde in water. When the MFC biosensor is exposed to a large formaldehyde concentration range from a low concentration of 1x10^-3 mg/L to a high concentration of 3 mg/L in water, it is found that a real-time current drop is observed after each formaldehyde injection. Afterwards, the current does not recover, which indicate that the formaldehyde kills some electroactive bacteria. Furthermore, measurement results show that a higher formaldehyde concentration results in a larger current drop percentage. By fitting the experimental results, we obtain a mathematical relationship between the formaldehyde concentration and normalized current drop percentage, which can be utilized for measuring the concentration of formaldehyde in water. Further analyzing the normalized current drop percentage versus formaldehyde concentration shows a sigmoid dose-response relationship, which is in agreement with traditional toxicology dose-response curve obtained by other measurement techniques. As a result, besides being utilized as biosensor for determining the concentration of formaldehyde, the biosensor can be utilized to monitor the dose-response curve of toxic chemicals in water. Due to the low-cost and real-time monitoring capability, the microfluidic MFC biosensor has potential for toxic pollutant in water monitoring and dose response-curve determination.