Fig. 2.
Numerical simulation of the long-range and short-range magnetic field gradients. (A) The long-range magnetic field gradient is generated by the external permanent magnets. The magnitude of the downward (−y direction) gradient (>200 T/m) extends over the full length of the main fluidic channel. (Inset) See Fig. S1 for position of the external magnets. (B) An abrupt change in relative permittivity (μr) between the microfabricated nickel features (μr ≈ 200) and the surrounding material (μr ≈ 1) creates large short-range magnetic field gradients in the vicinity of the MFS. The magnitude of this gradient is high (>104 T/m) and it extends ≈8 μm from the MFS. The large magnetophoretic forces for target deflection are generated by these short-range gradients. The height of the image corresponds to the height of the fluidic channel.