On-chip magnetic field modulation for distributed immunomagnetic detection of circulating tumor cells

Immunomagnetic assay combined with microfluidic technology has been proved to be an effective tool to detect rare Circulating Tumor Cells (CTCs), which helps to reveal valuable information for cancer diagnosis and prognosis. We introduced an immunomagnetic microsystem with patterned metallic nanomagnets integrating on the substrate to locally modulate the on-chip magnetic field for better capture performance. Here we further investigated the characteristics of the system by demonstrating the nanomagnets evenly distribute the target CTCs across the substrate, avoiding cell clustering and increasing the channel space usage by 23%; the nanomangets separate the CTCs from excessive free nanoparticles, reducing the overlapping degree by 20%; the nanomagnets improve the capture rate for 30% in spiked experiments; We also did theoretical calculations and got consistent results with the experimental data.