A quasi-3D impedance measurement using the square wave method with parallactic excitation for detection of biofilm growth

The detection and monitoring of microorganisms are of emerging interest for various industries. In this regard, an extremely important issue is biofilm-related infection in the healthcare industry demanding their early detection and monitoring. For several decades, impedance sensors have garnered significant interest in detecting bacteria due to their simple and label-free measurements. A fast impedance measurement device based on time-domain analysis was developed and used for monitoring the formation of Escherichia coli (E. coli) biofilms in real time. Using an electrode array providing 2-D information together with parallactic excitation yielded quasi-3-D resolution. A chamber with 2 × 16 electrodes was designed for this purpose. For evaluation of the time-domain-based measurement, we compared it with impedance measurements in the frequency domain, which showed a similar trend in impedance measurement. A finite element method (FEM) modeling has been utilized for reverse problem-solving or image reconstruction. The reconstructed images were then compared with confocal laser scanning microscopy (CLSM) images yielding a promising correlation. Therewith, the feasibility of using the fast impedance measurement for the detection of biofilm growth with quasi-3-D resolution has been demonstrated. This approach can serve as a viable method for the development of portable devices dedicated for the detection of tissue infections.