AC electrokinetic platform for manipulation of microfluids and micro/nanoparticles.

摘要

A general operation platform would benefit Lab-on-a-Chip (LOC) technologies significantly, allowing the user to focus their efforts on specific application protocols rather than custom design and operation of the microfluidic systems. The objective of this work is to propose a concept of electrokinetically driven microfluidic platform serving as the most fundamental layer of LOC devices. This platform is capable of essential operations including transport and mixing of microfluids and separation of particles. The electrokinetic actuation method rivals other actuation mechanisms for its simple fabrication, high degrees of parallelization and integration, and capabilities of multi-purpose manipulation of microfluids and micro/nanoparticles.;Due to the high complexity of the behavior of microfluids and micro/nanoparticles in microfluidic networks as well as the specialized operation protocols for various LOC applications, present work will focus on the design of individual components which can be easily integrated and parallelized on a chip. Firstly, a novel design of microgrooved channel is presented for transporting and pumping microfluids with different ion concentrations. Numerical simulation results indicate that the proposed pump possesses tunable transport capacity and pumping rate that can be improved greatly compared to the existing pumps with planar configurations. Secondly, a hybrid mixer consisting of both passive geometrical elements and active electrical actuation is proposed for fast mixing in microchannels. The geometrical features in the ceiling of the microchannel can generate helical flows while the electrode structure on the bottom induces vortex stirring. Experimental observations confirmed that the mixing efficiency of the hybrid mixer is much superior to a mixer with only one form of the mixing actuations. An optimization methodology is developed and applied for the shape optimization of the proposed hybrid mixing configuration. Finally, the complex behavior of micron and submicron particles suspended in aqueous fluids under AC electric fields is analyzed and experimentally characterized. Based on the experimental observations and theoretical analysis, a concept of electrohydrodynamic flow mediated dielectrophoretic separator is proposed and evaluated.