非磁性细微颗粒的负磁泳耦合分选规律研究

Investigation on the sorting regularity for non-magnetic micro-particles by negative magnetophoretic coupled sorter

非磁性细微颗粒的磁泳分离在生物工程、材料工程和环境工程等领域具有广阔的应用前景.为了分选直径非常接近的非磁性微粒,设计了负磁泳耦合的水动力分选器,为了确保分选器具有优异的性能,数值研究了在不同的磁场强度、磁铁个数、微通道参数、入口流速和速度比时,3,4,5μm的3种非磁性颗粒的运动轨迹,计算3种颗粒侧向偏移和颗粒分布带之间的距离(即带间距).结果表明:3种细微颗粒的侧向偏移距离和带间距都随磁场强度和颗粒尺寸的增大而增大;但是颗粒的侧向偏移并不会因为磁铁数量的增加而持续增加;颗粒的分离效果随着入口流速的减小,流速比的增大而提高.此外,当微通道结构参数Ha/Hb越小,不同颗粒分布带之间的距离就越大,不同直径的颗粒就越容易分离;最后,利用微-PIV实验获得了3种颗粒带的分布,并计算颗粒分布带宽和带间距,与数值模拟结果比较发现一致性很好.研究结果对非磁性颗粒分选器的设计具有指导意义.

Separation of micro-particle have great potential applications in the fields of bioengineering, material engineering and environment engineering and so on. In order to sort non-magnetic micro-particles with a very close diameter, a negative magnetophoretic coupled sorter is designed on the basis of hydrodynamic sorter. For assuring the excellent sorting performance of designed sorter, numerical simulations for the calculation of distribution of non-magnetic micro-particles with a diameter of 3, 4, 5 μm after separation process were carried out under different magnetic flux densities, at different inlet velocities and velocity ratios of two inlets in the microchannel with different parameters. The numerical results show that, greater lateral deflection of non-magnetic particles can be induced by more powerful magnetic field and bigger particle diameter. However, the deflection doesn’t increase with the magnets number continuously. Separation efficiency of non-magnetic particles was increased at lower inlet velocity and greater inlet-velocity ratio. Moreover, the smaller Ha/Hb can lead to greater space between two particle-bands for facility separation. Finally, the micro-PIV experiments were conducted to calculate the bandwidth and space of particle-band. The agreements of experimental and numerical results verify the validity of our numerical approach. It is instructive to guide the design of non-magnetic sorter.