Simultaneous diamagnetic and magnetic particle trapping in ferrofluid microflows via a single permanent magnet |
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| Authors: | Yilong Zhou Dhileep Thanjavur Kumar Xinyu Lu Akshay Kale John DuBose Yongxin Song Junsheng Wang Dongqing Li Xiangchun Xuan |
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| Affiliation: | 1Department of Mechanical Engineering, Clemson University, Clemson, South Carolina 29634-0921, USA;2College of Marine Engineering, Dalian Maritime University, Dalian 116026, China;3College of Information Science and Technology, Dalian Maritime University, Dalian 116026, China;4Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada |
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| Abstract: | Trapping and preconcentrating particles and cells for enhanced detection and analysis are often essential in many chemical and biological applications. Existing methods for diamagnetic particle trapping require the placement of one or multiple pairs of magnets nearby the particle flowing channel. The strong attractive or repulsive force between the magnets makes it difficult to align and place them close enough to the channel, which not only complicates the device fabrication but also restricts the particle trapping performance. This work demonstrates for the first time the use of a single permanent magnet to simultaneously trap diamagnetic and magnetic particles in ferrofluid flows through a T-shaped microchannel. The two types of particles are preconcentrated to distinct locations of the T-junction due to the induced negative and positive magnetophoretic motions, respectively. Moreover, they can be sequentially released from their respective trapping spots by simply increasing the ferrofluid flow rate. In addition, a three-dimensional numerical model is developed, which predicts with a reasonable agreement the trajectories of diamagnetic and magnetic particles as well as the buildup of ferrofluid nanoparticles. |
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