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. Author manuscript; available in PMC: 2012 Jun 15.
Published in final edited form as: J Am Chem Soc. 2011 May 24;133(23):9129–9135. doi: 10.1021/ja203981w

Figure 3. Simulation of magnetic capture.

Figure 3

(A) Section view of the MIMED trapping chamber illustrates the magnetic gradient across the channel wherein beads experience a pull-down force of ~10 -pN. (B) Sum of the magnetic (Fmx) and drag forces (Fdx) exerted on a stationary bead at 6, 60, 600 mL h −1. At 6 and 60 mL h−1, Fm exceeds Fd throughout all three trapping regions, enabling efficient bead capture (shaded regions). However, at 600 mL h−1, this only occurs by a narrow margin in the last trapping region (< 1 pN), suggesting potential for sample loss. (C) Experimental verification of simulation predictions of bead capture at the three stable equilibria established by the permanent magnets. (D) Efficiency of bead capture is measured vs. flow rate. Triplicate trials indicated ~100±0.3% bead capture at 6.0 and 60 mL h−1. At 600 mL h-1, capture efficiency decreases to ~42±16%.