A MEMS Microfluidic Mixer with Electrostatic Actuation

Bio-MEMS (Bio-Micro-electro-mechanical Systems) have been widely used for disease diagnosis and treatment.In bio-MEMS devices, the mixing of different micro-fluidics is frequently needed.However, such mixing has been very challenging due to the fact that micro-fluidic is generally laminar flow.As a result, MEMS mixers which can enhance the mixing of different micro-fluids are in pressing need.In this paper, the design and simulation of a 3-way pressure disturbance based micro-fluidic mixer for Bio-MEMS (bio-micro-electromechanical systems) application is proposed.Three aqueous solutions with different concentrations represented by different colors (sea blue, sky blue and red) are introduced through six inlets.The mixing of micro-fluid in the proposed mixer is analyzed.The parameters of the mixer are decided through the theoretical analysis.Based on results of the experiment simulation, almost 100% mixing can be finished within a mixing distance x equal to3.24mm of outlets for flow rates ranging in 1000um/s, and when the micro-fluids (3 kinds of liquids) near the outlets, the mixing degree is better.More or less than this velocity, the micro-fluids cannot get a good mixing.ANSYS simulation is used to verify the effectiveness of the MEMS mixer device.Compared with passive mixer, the pressure disturbance design with the straight channel diffusion model mixer is easier to fabricate and it makes device smaller and cheaper.The fabrication flow of the MEMS mixer is also suggested in this paper.The proposed MEMS mixer can be used for lab-on-a-chip, digital micro-fluidics, PCR amplification, DNA analysis, cell manipulation, cell separation and other applications.