A bio-inspired reference electrode: Regulating the respiration of micro-organisms

Abstract

Inspired by the possibility of controlling the respiration of micro-organisms, we present a bio-inspired reference electrode, demonstrating a stable potential for extended period of time. The bio-inspired reference electrode, made of platinum, sits in a microfluidic chamber for growing specific micro-organisms, Geobacter sulfurreducens, which is an exoelectrogen capable of transferring electrons outside its outer membrane to complete its respiration process. Open circuiting the reference electrode forces exoelectrogens on the electrode unable to transfer electrons to the electrode to complete the respiration process. This will set the reference potential to be the open circuit potential of the anolyte, sodium acetate, which is ~ -0.5 V versus the Ag/AgCl in 3M NaCl. The bio-inspired reference electrode maintained its potential stability of ±1.07 mV/day for over a week. The bio-inspired reference electrode was integrated in a MEMS microbial fuel cell (MFC) to characterize its electrochemical characteristics, including polarization, voltammetry, and electrochemical impedance spectroscopy.