MIXING AND SAMPLING IN A MICROFLUIDIC CHANNEL USING ROTATING MAGNETIC MICROBEADS
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This work presents a novel microsystem utilizing an array of rotating magnetic beads inside a microfluidic channel. The magnetic beads are actuated via an external rotating magnetic field dynamically magnetizing small (<10 µm) soft magnetic features. Presented here is the method for fabricating the soft magnetic features via electron beam evaporation. The physical operational limits of the device are demonstrated and quantified. The hypothesis of the work is that the actuation of the magnetic beads will rapidly mix the system and the rapid mixing will increase the chance that a functionalized target particle will come into contact with the magnetic bead. The target could then be trapped via a protein-protein bond with the functionalization on the magnetic bead. The first operation, microfluidic mixing, is the ability for these beads to mix fluids inside a microfluidic channel. This is done by measuring the mixing of two streams of fluid as they flow over the rotating array of beads. This method demonstrated significant mixing (65%) in less than 300 µm of channel length if the magnetic beads are actuated at a high enough velocity relative to the bulk flow velocity. The second operation is the capacity to capture particles from the microfluidic channel. This capturing is accomplished via protein-protein bond between the surface functionalizations of the magnetic bead and the particle. This device demonstrated the capacity to capture >80% of particles that pass through the 400 µm array. This result was demonstrated in channels where the magnetic beads occupied less than 25% of the channel height.