BACKGROUND: Microalgae is an important natural resource, which has been used in various fields such as health care, chemical industry, clean energy, and environmental protection. However, microalgae samples are prone to be contaminated by bacteria, impurities, or other hybrid microalgae species. Enrichment and purification must be carried out before further research and utilization.RESULT: Herein, a microfluidic microalgae enrichment and purification system based on the principle of deterministic lateral displacement (DLD) was proposed. Two different shapes of micro-post, circular and triangular, were designed. The performance of the two chips was analyzed from many aspects, such as stability, throughput, recovery efficiency, purity, and enrichment factor. Using Platymonas cells as the samples, enrichment and purification were performed with the two chips. Experimental investigations revealed that the triangular-shaped chip has a better performance than circular-shaped chip; the recovery efficiency of Platymonas cells of the triangular-shaped chip was 85.7%, the purity was 89.4%, and the maximum throughput was 500 ∼L/ min, the enrichment factor was 92.CONCLUSION: To our knowledge, this is the first time that DLD technology has been applied to the enrichment and purification of microalgae cells. In addition, the performance of different chips was discussed. Those findings should make a driving contribution to the enrichment and purification of microalgae, DLD technology, and the utilization of microalgae resources.
Identification of circulating tumor cells (CTCs) from a majority of various cell pools has been an appealing topic for diagnostic purposes. This study numerically demonstrates the isolation of CTCs from blood cells by the combination of dielectrophoresis and magnetophoresis in a microfluidic chip. Taking advantage of the label-free property, the separation of red blood cells, platelets, T cells, HT-29, and MDA-231 was conducted in the microchannel. By using the ferromagnet structure with double segments and a relatively shorter distance in between, a strong gradient of the magnetic field, i.e., sufficiently large MAP forces acting on the cells, can be generated, leading to a high separation resolution. In order to generate strong DEP forces, the non-uniform electric field gradient is induced by applying the electric voltage through the microchannel across a pair of asymmetric orifices, i.e., a small orifice and a large orifice on the opposite wall of the channel sides. The distribution of the gradient of the magnetic field near the edge of ferromagnet segments, the gradient of the non-uniform electric field in the vicinity of the asymmetric orifices, and the flow field were investigated. In this numerical simulation, the effects of the ferromagnet structure on the magnetic field, the flow rate, as well as the strength of the electric field on their combined magnetophoretic and dielectrophoretic behaviors and trajectories are systemically studied. The simulation results demonstrate the potential of both property- and size-based cell isolation in the microfluidic device by implementing magnetophoresis and dielectrophoresis.
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