A biologically-inspired electro-chemical reference electrode

The paper report a unique biologically inspired electro-chemical reference electrode based on regulating the breathing of bacteria. Some species of bacteria, named exoelectrogen, have the capability of extracellular electron transfer, which is the transfer of electrons to a solid electron acceptor outside their membrane. We find that it sets the solid electron acceptor at a stable electrochemical potential, which can be used as reference electrode. We pattern thin film platinum as electron acceptor and grow exoelectrogenic biofilm on it. By performing colorimetric analysis of the individual ions in the anolyte solution, we confirmed that the potential of the reference electrode, ∼ −0.5 V versus the Ag/AgCl in 3M NaCl, arises from the electrochemical potential of the reaction. The biologically-inspired reference electrode demonstrates a stability of ±4.2 mV/day for two days. It is integrated in a MEMS microbial fuel cell (MFC) to characterize its electrochemical characteristics.