Numerical study and Taguchi optimization of fluid mixing by a microheater-modulated alternating current electrothermal flow in a Y-shape microchannel

This paper presents the numerical analysis and Taguchi optimization of fluid mixing by alternating current electrothermal flow (ACET) in a Y-shape microchannel. In the numerical study, ACET is simulated through the interaction of a non-uniform electric field provided through co-planar electrodes and the temperature gradients produced by a micro-heater. To achieve the efficient ACET mixing of fluids, a parametric study of various factors affecting the structure and strength of ACET is first performed and then, a detailed physical interpretation of the results is presented. The factors include the applied electric potential, the location, size, and heating intensity of a micro-heater, the inlet velocity ratio of fluids mixed, and the cross-sectional aspect ratio of a Y-shape microchannel. Optimum condition of the factors is determined using the Taguchi method to maximize the fluid mixing by ACET. Results show that the ACET-based mixing is affected, in order of importance, by the inlet velocity ratio of fluids, the applied electric potential, the cross-sectional aspect ratio of a Y-shape microchannel, and the location, heating intensity, and size of a micro-heater. Under the optimum condition of the factors, a high mixing efficiency of 90.4 % is achieved in the microchannel. The ACET mixing at the optimum condition is experimentally verified by fabricating micro-mixers and confirming the concentration change of fluids introduced into the mixers. These results provide valuable engineering insights into the design and development of not only ACET-based microfluidic devices including a micro-mixer but also lab-on-a-chip systems for bioassay where the devices are integrated.