An analysis of interdigitated electrode geometry for dielectrophoretic particle transport in micro-fluidics

As researchers work to develop the “Lab-on-a-Chip” system, dielectrophoresis (DEP) is being examined as a mechanism for the micro-fluidic transport and separation of small biological samples such as cells, proteins, and DNA. Interdigitated electrodes are commonly used within such devices to generate the non-uniform electric fields that induce movement. Among other parameters, the magnitude of the DEP force depends upon the gradient of the square of the electric field that is generated by such electrodes. By understanding the effect that the dimensions of the electrodes have on this quantity, micro-fluidic devices can be designed to produce the most effective dielectrophoretic effect on the biological samples. This article examines the relationship between the geometry of the interdigitated electrodes and the magnitude of the DEP force. This is done by obtaining and analyzing an equation for the gradient of the square of the electric field. The equation is generated by fitting the results of extensive numerical simulations. Although the complete equation introduced in this work is based upon theoretical results, many fundamental portions of the present work agree with accepted experimental results. These verifications are also addressed.