Abstract
We have successfully demonstrated a portable microbial fuel cell that is capable of autonomously discharging CO2 bubbles and agitating aqueous anolyte to prolong its operation lifetime and facilitate the electron transport inside. This fuel cell consumes glucose and oxygen to generate electricity in a reaction catalyzed by encapsulated microorganisms. The bio-catalysts, fuels, and liquid electrolytes are sealed inside two liquid-impermeable compartments separated by a proton exchange membrane. In order to discharge generated CO2 gas, this fuel cell is equipped with a bubble guiding and venting system, which releases the pressure built inside the anode compartment and agitates the anolyte as well. In the prototype demonstration, an open-circuit potential of 0.37 V per single unit and an average power output of 32.16 μW/cm3 in the first hour is achieved. With 40 milligrams of glucose fuels, the prototype cell can continuously operate for more than 4 hours. Furthermore, a fuel-cell stack of 6 units, which has an overall potential over 1.5V, were built and successfully power a light emitting diode. As such, this fuel cell is capable of self-regulating the electricity harvesting process and producing steady voltage and current outputs for portable applications.