Effect of induced charge forming active vortex structures in serpentine microchannels on fluid mixing driven by pressure flow

The incorporation of induced charge into the serpentine curved micromixers driven by negative pressure (Np) can serve as an efficacious way for improving micromixing quality. To comprehensively investigate the hydraulic characteristics and mixing capacity of this model, an investigation is conducted using finite element method. The results indicate that when |−30| Pa ≤ Np ≤ |−50| Pa, active vortex pairs formed by electroosmosis flow on the conductive plate surface are fully developed, which strengthens the chaotic convection and leads to a uniform mixing. For |−50| Pa < Np ≤ |−200| Pa conditions, the compression of pressure flow causes the separation and degradation of active vortex pairs. However, increasing the electric field intensity around the conductive plate, such as forming a shrinking microchannel, or increasing the induction area of the plate, such as rotating the conductive plate, can make the active vortex play a beneficial role again, as both the Zeta potential and slip velocity on the plate surface are enhanced. For |−200| Pa < Np ≤ |−500| Pa conditions, the pressure flow gradually dominates the mixing process. But the conductive plate with combined optimal parameters can increase the mixing quality to above 0.8 when Np varies in border range.