Department of Mechanical Engineering, Clemson University , Clemson, South Carolina 29634-0921, United States.
MOA Key Laboratory of Agricultural Information Acquisition Technology (Beijing), China Agricultural University , Beijing 10083, China.
Anal Chem. 2017 Jun 20;89(12):6915-6920. doi: 10.1021/acs.analchem.7b01608. Epub 2017 Jun 8.
Magnetic fluids (e.g., paramagnetic solutions and ferrofluids) have been increasingly used for label-free separation of nonmagnetic particles in microfluidic devices. Their biocompatibility, however, becomes a concern in high-throughput or large-volume applications. One way to potentially resolve this issue is resuspending the particles that are separated in a magnetic fluid immediately into a biocompatible buffer. We demonstrate herein the proof-of-principle of the first integration of negative magnetophoresis and inertial focusing for a simultaneous separation and washing of nonmagnetic particles in coflowing ferrofluid and water streams. The two operations take place in parallel in a simple T-shaped rectangular microchannel with a nearby permanent magnet. We find that the larger and smaller particles' exiting positions (and hence their separation distance) in the sheath water and ferrofluid suspension, respectively, vary with the total flow rate or the flow rate ratio between the two streams.
磁性液体（例如顺磁溶液和铁磁流体）已越来越多地用于在微流控装置中无标记分离非磁性颗粒。然而，其生物相容性在高通量或大容量应用中成为一个关注点。解决这个问题的一种方法是将在磁性液体中分离的颗粒立即重新悬浮在生物相容性缓冲液中。本文首次证明了用于同时分离和洗涤共流铁磁流体和水射流中非磁性颗粒的负磁泳和惯性聚焦的集成原理。这两个操作在具有附近永磁体的简单 T 形矩形微通道中并行进行。我们发现，较大和较小颗粒在鞘水和铁磁流体悬浮液中的排出位置（因此它们的分离距离）分别随总流速或两流之间的流速比而变化。
