Electrochemical Detection of Microorganisms Using an Electrochemical Quartz Crystal Microbalance

We attempted evaluation of biofilm formation by the electrochemical quartz crystal microbalance (EQCM) method. The EQCM method is applicable to in situ settings and may be able to determine corrosion and a chemical reaction on materials under the influence of biofilm formation. We used Au having high chemical stability to measure frequency and changes of the potential with biofilm formation alone. Additionally, sample surfaces were examined by a conventional biofilm formation assay such as fluorescent X-ray analysis and Raman spectroscopy. We conducted three types of experiments, 1st: rest-potential measurement, 2nd: spontaneous-potential measurement, and 3rd: constant-potential measurement. From the results of these measurements, it was concluded that frequency changes depend on changes in the potential. We investigated biofilm formation by conventional methods of evaluation and found that the above phenomenon was caused by concentration of ions such as Ca2+ and Cl− from tap water in biofilm. In the positive voltage range, the magnitude of biofilm formation was inhibited by a halogen ion such as Cl−, whereas in the negative range, cations such as Ca2+ were concentrated at an accelerated rate. Therefore, electrochemical evaluation of biofilm formation was carried out successfully by means of Au, with high chemical stability. In conclusion, the EQCM method appears to be able to measure biofilm formation.

Keywords: Biofilm, Electrochemical, EQCM, Evaluation, In-situ measurement.