Electrochemical Signature of Escherichia coli on Nickel Micropillar Array Electrode for Early Biofilm Characterization

Biofilms are sessile microbial communities living at interfaces, in which the extracellular matrix is responsible for the mechanical stability and adhesion to surfaces. Transition from planktonic to attached cells is a key step in the biofilm formation process. Monitoring of this transition is needed to prevent contamination of biomedical devices and mitigate microbially influenced corrosion. Under anoxic local conditions and in the presence of an exogenous redox mediator, biofilms can divert part of the electron flow associated with catabolism to electrodes maintained at a defined potential. Extracellular electron transfer (EET) follows upon the attachment of planktonic cells to the surface. Modification of the electrode increases bacterial attachment, thus allowing early bioelectrochemical detection of the biofilm. Here, we report a Ni electrode micropillar array to detect early attachment of Escherichia coli biofilm through mediated EET in potentiostat-controlled electrochemical cells. The biofilm-surface interaction is studied by using electrochemical impedance spectroscopy (EIS) at different potentials and temperatures over 24 h. The analysis of the EIS signature highlights the effect of temperature on mediated EET in biofilms. These results demonstrate that micropillared electrodes allow earlier biofilm detection than flat electrodes, which is relevant to biofilm sensing and investigation of microbially influenced corrosion in drinking water systems and biomedical devices.