Abstract

There are a number of analytical methods available for the characterization of a biofilm. The most commonly used techniques include gravimetric methods such as quartz crystal microbalances or surface acoustic waves, optical microscopy, surface plasmon resonance (SPR), anemometric as well as electrochemical or electrical methods.

Recently electrical impedance spectroscopy (EIS) has been studied as an alternative method as well. In EIS, the change of the surface impedance is measured as a result of a biofilm deposition. We have developed an EIS based measurement cell, that consists of a polymer microfluidic flow cell with electrodes and a custom-built measurement electronics. With the given setup we have been able to successfully monitor the growth of a biofilm (Pseudomonas aeruignosa, Stenotrophomonas maltophilia).

For this, the respective bacteria have been probed across the electrodes for an interval of three hours after which the system was continuously purged with feeding medium. As time processed the surface impedance increases as a result of the formation of the biofilm.

We have done comparative measurements with an electrode which has been probed with the bacteria (measurement electrode) compared to an electrode that has not been probed (reference electrode) in order to verify the growth of the biofilm. For both cases the impedance has been measured over time. Both electrodes have been inspected by means of microscopy in order to verify the growth (in case of the measurement electrode) and the absence (in case of the reference electrode) of the biofilm.