Electrokinetics have been widely used in lab-on-a-chip devices for fluid manipulation applications. The AC electrothermal (ACET) effect is a highly efficient technique for biofluids (σ>0.1 S/m) active micromixing, which can be used in chemical, biological, and medical analysis systems. In this paper, a novel idea of employing microelectrode arrays placed on sidewalls of a fluidic microchannel for increasing the mixing efficiency of biofluids is numerically investigated. It was reported that coplanar asymmetric microelectrode arrays are capable of creating ACET vortices in the bulk of a high conductive electrolyte solution. Two electrode arrays can be placed on the sidewalls of a microchannel, each of which has a different role, one pumps the biofluid while the other mixes it. Two different actuation patterns were applied to the electrodes. One pair of microelectrodes was simulated and the simulation procedure was then verified by conducting experiments for ACET flow measurement in a similar geometry. Microelectrode arrays were fabricated on 1mm thick glass substrates using photolithography. A 800 μm thick fluidic microchannel was fabricated by soft lithography of Polydimethylsiloxane (PDMS). The results showed that such a technique can dramatically increase the mixing of the solution while pumping is taking place. The mechanism was capable of efficiently mixing biofluid solutions (resultant concentration ratio of up to 80%) in a short time (<3 min) and short distance (<600 μm) for a 300×300 μm2 fluidic microchannel cross section area. Medical analysis such as heterogeneous immunoassays can be potential applications of such micromixing technique.

Date Published: 5 March 2015
PDF: 7 pages
Proc. SPIE 9320, Microfluidics, BioMEMS, and Medical Microsystems XIII, 93201C (5 March 2015); doi: 10.1117/12.2081573

Published in SPIE Proceedings Vol. 9320:
Microfluidics, BioMEMS, and Medical Microsystems XIII
Bonnie L. Gray; Holger Becker, Editor(s)