Figure 1. Micromagnet-integrated microfluidic device and characterization of micromagnets.

(a) Schematic illustration of the glass substrate patterned with micromagnets for immunomagnetic isolation of cancer cells. Permanent magnets provide external magnetic field and magnetize micromagnets to induce local magnetic field enhancement. Magnetic nanoparticles-labeled CTCs are captured to the channel substrate by the arrays of micromagnets as the blood sample flows through the microchannel. (b) Schematic of the patterned thin-film micromagnet array showing the lateral dimensions, thickness, and spatial periodicity. Magnetic field distribution of an array of five micromagnets (brown blocks) within a microfluidic channel space obtained using COMSOL. The strongest spots of magnetic field are around the edges of the micromagnets. (c) SEM image of fabricated micromagnets. (d) Schematic shows the setup of the screening system with dimensions of the microchannel.