Interdigitated impedance sensors for analysis of biological cells in microfluidic biochips

In the presented work we describe the novel combination of contact-less dielectric microsensors and microfluidics for quantitative cell analysis. The lab-on-a-chip system consists of microfluidic channels and chambers together with integrated and passivated interdigitated electrode structures. In contrast to existing bioimpedance methods implemented for cell analysis, the dielectric microsensors are completely insulated and physically removed from the liquid sensing environment using defined multi-passivation layer of distinct size and composition. Consequently, these structures act as contact-less microsensors for the characterization of in vitro cultivated cells. The overall performance of the system is demonstrated on various bacterial and yeast strains. Due to the high sensitivity of the contact-less dielectric microsensors it is possible to directly identify microbial strains, based on morphological differences and biological composition in the absence of any indicators or labels. Additionally, dielectric changes occurring in sub-cellular structures such as membranes can be directly monitored over a wide frequency range. As a result, microfluidic biochips are developed to continuously monitor cell morphology changes in a non-invasive manner over long periods of time. © 2009 Springer-Verlag.