Micro-Mixing Chambers

Despite the sub-millimeter scales of micro-fluidic devices, the miniscule diffusivity of proteins and drugs compounds (10-7 - 10-6 cm2/sec) stipulates that most reactions/biochemical docking are diffusion limited with an excessively high diffusion time of hours to days. Stirring and mixing are the usual remedies at larger scales to enhance the transport rates. However, stirring is difficult for micro-devices as inertial pumping and moving parts are unavailable at such scales. The group has been able to generate sub-mm vortices with novel non-linear DC and AC electrokinetic mechanisms that allow non-uniform surface slip velocities to drive intense micro-vortices. Shown below are mm-sized conducting granules that can rattle electrophoretically in the presence of a low-frequency AC field but will also carry with it two intense micro-vortices shown below.These vortices reduce the mixing time of two solutions from 1 hour to 1 minute. Micro-mixers driven by AC fields across microfabricated electrodes have also been designed, as described in the micro-pump section.

Related Publications : [142],[147],[148],[156],[158],[159]