Authors: G.A. Ferrier, S.F. Romanuik, D.J. Thomson, G.E. Bridges, M.R. Freeman
Affilation: University of Manitoba, Canada
Pages: 589 - 592
Keywords: dielectrophoresis, capacitance, electromanipulation, Clausius-Mossotti factor
Previously, we demonstrated a system that can detect the presence of yeast cells using capacitance measurements from a cavity resonator. The resonator is coupled to a set of electrodes, which are aligned 90 degrees relative to the flow direction of a microfluidic channel that is 25 microns in height. Using these electrodes, we can dielectrophoretically manipulate cells using low frequencies (up to MHz) and perform capacitive detection using high frequencies (GHz). By implementing interdigitated electrode designs in this system, we gain insight into the dynamic position of flowing yeast cells relative to the electrodes. Based on the shape of the capacitance signatures from the interdigitated electrodes, we can determine the sign of the Clausius-Mossotti factor of yeast cells in less than 2 s. With this information, one could adjust the operating frequency to approach the crossover frequency (when the Clausius-Mossotti factor is zero), which in general can be used to identify different types of cells, their condition (are they cancerous?), and whether they are viable or not. For viable yeast, the crossover frequency is approximately 100 kHz. By applying 10 kHz and 1 MHz frequencies, we generate conditions where yeast cells are either repelled from or attracted to the electrodes.