Fluid particles flow in a microchannel with highly ordered laminar fashion. For this reason, two different fluid streams cannot mix easily, or it takes a very long time. The problem becomes intense for large molecules such as peptides, proteins, and nucleic acids during rapid mixing for biochemical applications in a micro laboratory. To do the mixing at the microscale, external stimuli are necessary to stir the fluid. Mechanical stimuli aren't suitable for this purpose because of moving parts. The other way of mixing is to apply an AC electric field. When an electric field is applied in the microscale region, an electroosmotic flow field is generated. This can cause fluid particles to go from one layer of fluid to another layer. This principle was used to make a micromixer for this research. First, the four microelectrodes were sputtered on top of a silicon wafer.  Two electrodes were placed in one wall and the other two were placed in the opposite wall of the channel. AC electric field was applied in the electrodes using a function generator. Then a perfusion chamber was placed on top of the silicon wafer to contain the fluid in the gap of the microelectrodes. Flow pattern was observed in the electrodes gap using the micro-PIV (Particulate Image Velocimetry) system. It was observed that after applying AC electric field the fluid streamlines became turbulent and created a mixing zone in the electrodes gap. The flow field of the mixing zone was analyzed for different applied voltage and frequency. The micromixer was also modeled numerically to optimize the micromixer design. The effect of variation of interspacing distance between electrodes on the flow field was observed. The flow field was analyzed in terms of the electric field generated by the electrodes. The mixing efficiency was analyzed in terms of the concentration gradient of the incoming and outgoing fluid stream. Numerical results were compared with experimental results and the deviation of the results was explained. These results could play an important role to design and improve a micromixer design using an electric field. A micromixer has many potential applications in biology (DNA analysis, enzyme Screening), chemistry (synthesis, polymerization) and detection (drug discovery, diagnosis).


Experimental and Numerical Analysis of Fluid Flow Through a Micromixer With the Presence of Electric Field

Division / Sponsors: 
Heat Transfer Division (HTD), Fluids Engineering Division (FED)

Heat Transfer Summer Conference
Paper Proceedings: https://asmedigitalcollection.asme.org/HT/HT2020/volume/83709

18th International Conference on Nanochannels, Microchannels, and Minichannels
Paper Proceedings: https://asmedigitalcollection.asme.org/ICNMM/ICNMM2020/volume/83693

Fluids Engineering Division Summer Meeting
Paper Proceedings: https://asmedigitalcollection.asme.org/FEDSM/FEDSM2020/volume/83716

HT-ICNMM2020 - Virtual Conference, SHTC - Virtual Conference, FEDSM2020 - Virtual Conference

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