Impedimetric sensor cell for monitoring biofilm growth
1Institute of Microstructure
Technology (IMT), Karlsruhe Institute of Technology (KIT)
2Institute of Functional Interfaces
(IFG), Karlsruhe Institute of Technology (KIT),
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.