Single Magnetic Bead Detection in a Microfluidic Chip Using Planar Hall Effect Sensor

In this study, we fabricate an integrated microfluidic chip with a planar Hall effect (PEE) sensor for single magnetic bead detection. The PILE sensor was constructed with a junction size of 10 mu m x 10 mu m using a trilayer structure of Ta(3 nm)/NiFe(10 nm)/Cu(1.2 nm)/IrMn(10 nm)/Ta(3 nm). The sensitivity of the PILE sensor was 19.86 mu V/Oe. A diameter of 8.18 mu m magnetic beads was used, of which the saturation magnetization was similar to 2.1 emu/g. The magnetic susceptibility chi of these magnetic beads was calculated to be similar to 0.14. The diluted magnetic beads solution was introduced to the microfluidic channel attributing a single bead flow and simultaneously the PILE sensor voltage was measured to be 0.35 mu V. The integrated microchip was able to detect a magnetic moment of 1.98 x 10(-10) emu.