Figure 1

(a) The device used in this study for DEP treatments of Listeria cells. It consists of a chamber formed by silicone rubber and a set of interdigitated microelectrodes at the floor of the chamber. The interdigitated electrode has a total of 40 pairs of finger electrodes, each measuring 25 μm of electrode width and 25 μm of space. (b) Schematic of the non-uniform electrical field generated by the interdigitated microelectrodes, and the positive and negative DEP for bacterial cells in this electrical field. The electrical field has its maximum in gradients and strength at the edges of finger electrodes and its minimum at the centers of the finger electrodes. Positive DEP moves cells to the edges of these finger electrodes where the electrical field is stronger, while negative DEP moves cells towards the centers of the finger electrodes between the electrodes where the electrical field is weaker.