Experimental study of flow characteristics and mixing performance in a PZT self-pumping micromixer

In this paper, a novel micromixer which possesses both pumping and mixing capabilities has been investigated by an externally triggered micro-PIV and the fluorescent tests. A mixing region with triangular-wave structures was integrated into an obstacle-type valveless micropump. The velocity and vorticity fields measured by micro-PIV indicated that the flow recirculation occurred upstream the obstacles and along the lateral direction of the triangular structures when the pump mode and supply mode were switched. Moreover, the distributions of recirculation regions varied rapidly due to the high frequency oscillating flow, which had significant effects in the mixing process. The mixing indices obtained from the mixture of fluorescent and blue dyes exhibited that the mixing region which is 2100 μm in length provided the best mixing effects. The advantages such as rapid and uniform mixing, device portability, easy fabrication, etc. were all attainable in this self-pumping micromixer. In the future, the pumping and mixing performances can be optimized based on the quantitative measure technologies.