Microfluidic bioanalytical system for biofilm formation indication

Abstract

The formation of biofilms is a key factor that researchers must consider when they work with bacterial cultures. We describe a new microfluidic bioanalytical sensory system for indicating biofilm formation. The method is demonstrated with Pseudomonas bacteria as an example and is based on the real–time recording of cell–polarizability changes caused by an alternating electric field. Control experiments using phase–contrast microscopy and traditional microbiological plating were done that proved biofilms had formed. The physical picture was described of the sensor–signal changes during cell transition from planktonic to biofilm growth. This transition was indicated by the appearance of a peak–shaped signal at 500 kHz and by an increase in the recorded relaxation time. Phenomena of increase in the signal relaxation time from 2.4 s for planktonic to 25.4 s for biofilm cells. The proposed microfluidic sensor system for indicating biofilm formation holds much promise, because it ensures an analysis time of about 20–30 min. An added bonus is that for this system there is no need to grow bacterial biofilms in a sensor and the flow cell is reusable.