Fully integrated detection of single magnetic beads in complementary metal-oxide-semiconductor

Microcoils are integrated with n-well Hall sensors in a complementary metal-oxide-semiconductor (CMOS) integrated circuit for the detection of individual superparamagnetic beads. The 4.2-mu m-wide microcoils, generating magnetic fields of 800 mu T with 10 mA of current, are used to polarize beads of 2.8 mu m in diameter. The resulting 10.8 mu T magnetization field induced in the bead is measured by a 4.7 mu m Hall sensor, stacked below the microcoil. The detection system has a sensitivity and resolution of 34 V/A T and 300 nT/root Hz, respectively. Integration of the magnetic bead detection onto a CMOS platform drastically reduces system cost, complexity, and power consumption, and marks an important milestone on the road to implementing low-cost, easy-to-use, point-of-care diagnostic assay. (c) 2008 American Institute of Physics.