Electrochemical Monitoring of Metallic Materials' Surfaces with Biofilm Formation

Abstract

Biofilms formed on materials by bacterial activity cause many engineering problems. It ranges from those at hospitals to toilets and kitchen at homes in various ways. To solve those problems, it is very important to analyze the phenomenon precisely and also to monitor the formation and growth process. To achieve the purpose, we have had many proposals for biofilm sensors so far. However, there are not so many proposals for rapid, easy and industrial biofilm sensors. In this research, we established the electrochemical system to monitor biofilm formation and growth to measure the equilibrium (static) potential and also dynamic polarization curves of metallic materials. And we discussed on how we should apply the results to evaluate biofilms on metallic materials. We used pure copper, titanium, iron and their alloys as specimen. The lead wire was attached to the tiny coupons (10mm x 10mm) and only the opposite side was exposed as electrode. Specimens (working electrode), helical platinum wire (counter electrode) and silver/silver chloride glass electrode in 3.3M KCl solution (reference electrode) were immersed into LB culture with E.coli (K-12, G6). And those three electrodes were connected to a potentiostat. The static potential change and polarization curves in the solution were measured, while the bacterial growth and biofilm formation/growth were going on. The equilibrium potentials for copper, iron and their alloys were shifted in less noble direction, while those of titanium and their alloys did not change and were almost constant. And the polarization curves were also reflected correspondingly. Those changes were discussed and they could be explained by the biofilm formation and growth.