Session 17-3

Magnetic Relaxation Detector for Microbead Labels
in Biomedical Assays

 

Abstract

A Hall-effect biosensor based on magnetic label detection is implemented in 0.18 µm CMOS. No external magnet, reference sensor or calibration is required. The sensor offset is suppressed to sub-µV by a mixed-signal feedback loop and correlated double sampling (CDS). Flicker noise and thermal noise are rejected by CDS and averaging. A single 4.5 µm bead is detected in 16 ms with a probability of error < 0.1%.