Study on the Improvement of Magnetic Bead Transfer Speed by the Combination of Microcoils and Parallel Wires using Two Metal Layers

In this study, we investigated the structure of micro-coils to transfer magnetic beads at higher speeds with two metal layers. Parallel wires were placed around a microcoil in two metal layers. The size of the microcoil and the parallel wire was 40µm square and a width of 10µm. The structure was fabricated in a 0.18-µm CMOS standard process, and the transfer experiments were performed on 4.5-µm-diameter magnetic beads. A uniform magnetic field of 2mT was applied from an external electromagnet, and a current upto 10mA was applied to the microcoils and the parallel wires. The magnetic beads were successfully transported between the two microcoils at an average velocity of 77µm/s.