MEASUREMENT OF ELECTRODE IMPEDANCE AND ELECTRODE CONTACT VOLTAGE FOR THE DETECTION OF MICROORGANISMS
Abstract
Rapid detection of microorganisms in liquid samples by means of electric impedance measurements has become a world-wide applied hygienic standard method. A so-called raster electrode method, specifically adapted for measurements on microorganism cultures, yielded effective analyses of dielectric properties providing information on both the dielectric properties of the liquid culture medium and the properties of the inserted electrodes. Without the need of reference measurements of electrode characteristics, the method allows for the low frequency determination of a cell culture's conductivity σ and permittivity ε as a function of cell concentration <i>n</i>. For routine monitoring of long-term growth processes, the novel method takes advantage of σ but also of time changes of the boundary layer's electric impedance and contact voltage. Accelerated detections are striven for by a pre-concentration of cells by dielectrophoresis prior to the impedance measurement. The new methods prove to be effective tools for the detection of different types of bacteria and yeast which show high relevance in food technology or medicine.
Event details
- Event
- XVI IMEKO World Congress
- Place
- Vienna, AUSTRIA
- Time
- 25 September 2000 - 28 September 2000