A laminar-flow based microbial fuel cell array

We created a novel laminar-flow based microbial fuel cell (MFC) array to be an integrable and scalable power source for portable lab-on-a-chip (LOC) devices. The microfluidic MFC enabled the laminar flow of anolyte and catholyte streams in a microchannel without any physical membranes while the device harvested electricity by utilizing ion transfers through the laminar interface which acts as a virtual membrane. The array prototype incorporated four series-connected fuel cells and was operated with two common inlets for the continuous introduction of the anolyte and catholyte. In the anodic flow region, microorganisms oxidized organic media and completed respiration by transferring the electrons to the anodes. The protons generated by the anodic reactions passed through the liquid-liquid interfaces and traveled to the cathodic streams. The electrons then moved across the external resistors to the cathodes where they combined with the protons and reduced oxidant (i.e. catholyte). The array generated a maximum power output of 60.5 μW/cm2 using a 100 kΩ load, which outperformed a single laminar flow MFC unit by a factor of approximately 4. The series or parallel application of this array structure, using microfluidic MFCs integrated into a single LOC device, can offer the potential for on-chip power generation.