Abstract
Effective and rapid mixing is essential for various chemical and biological assays. The present work describes a simple and low-cost micromixer based on magnetofluidic actuation. The device takes advantage of magnetoconvective secondary flow, a bulk flow induced by an external magnetic field, for mixing. A superparamagnetic stream of diluted ferrofluid and a non-magnetic stream are introduced to a straight microchannel. A permanent magnet placed next to the microchannel induced a non-uniform magnetic field. The magnetic field gradient and the mismatch in magnetic susceptibility between the two streams create a body force, which leads to rapid and efficient mixing. The micromixer reported here could achieve a high throughput and a high mixing efficiency of 88% in a relatively short microchannel.
Highlights
Rapid mixing in microfluidic devices is an important task for material synthesis, chemical/biochemical analysis, and cooling [1]
We demonstrated in our previous work [34] the expansion of a ferrofluid stream containing non-magnetic particles under the effect of the magnetic body force created by a uniform magnetic field
We examined the mixing of a ferrofluid stream into a water stream in a non-uniform magnetic field at different flow rates and concentrations
Summary
Rapid mixing in microfluidic devices is an important task for material synthesis, chemical/biochemical analysis, and cooling [1]. Micromixers have a broad range of applications such as for reactors [2,3,4], lab on a chip for chemical engineering [5], enhancement of chemical selectivity [6], extraction processes [7], drug discovery [8], polymer synthesis [9], and DNA amplification [10]. The challenge in designing micromixers is to achieve fast and efficient mixing within a short residence time or in a short microchannel. Depending on their operation mechanism, micromixers are categorized as passive or active. Passive mixers are easy to fabricate due to the fact that they do not need an external energy supply. Faster and more effective mixing can be achieved using active micromixers, which require an external energy source and a more complex fabrication process
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