Hydrodynamic Separation of Micron-sized Particles through Magnetization
Faculty Advisor(s): Lee
Many assays and lab-on-a-chip projects require the use of uniform magnetic particles. Creating magnetic particles of uniform size and magnetization is a difficult task. The next best alternative is to make a distribution of particles and separate them. Magnetic particles of similar size need to be separated based on their magnetization. In current research a chamber is placed over a strong permanent magnet. Magnetic SeradynTM particles are pumped through this chamber under Stokes’ flow, and the magnetic field gradient attracts highly magnetic particles. The particles are 40% by weight magnetite, Fe3O4, and they have a density of about 1.5 g/cm3. The highly magnetic particles are held against a wall of the chamber while weakly magnetic particles flow past the magnet and out of the chamber. The highly magnetic particles are collected by removing the magnet and emptying the chamber. By varying the distance between the chamber and the magnet or the flow rate, the minimum magnetization of collected particles can be altered. Preliminary results show that the best separation occurs when the chamber is placed 3 mm above the magnet and the flow velocity is approximately 1.5 mL/min. However to achieve adequate separation, the same sample must be run through the chamber three separate times. This greatly affects the efficiency of separation since only about 65% of the particles are recovered after each separation. In order to address this poor separation, a new flow chamber was built for future analysis.
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