Title :
Magnetic Relaxation Detector for Microbead Labels
Author :
Liu, Paul Peng ; Skucha, Karl ; Duan, Yida ; Megens, Mischa ; Kim, Jungkyu ; Izyumin, Igor I. ; Gambini, Simone ; Boser, Bernhard
Author_Institution :
Electr. Eng. & Comput. Sci. Dept., Univ. of California at Berkeley, Berkeley, CA, USA
fDate :
4/1/2012 12:00:00 AM
Abstract :
A compact and robust magnetic label detector for biomedical assays is implemented in 0.18-μ m CMOS. Detection relies on the magnetic relaxation signature of a microbead label for improved tolerance to environmental variations and relaxed dynamic range requirement, eliminating the need for baseline calibration and reference sensors. The device includes embedded electromagnets to eliminate external magnets and reduce power dissipation. Correlated double sampling combined with offset servo loops and magnetic field modulation, suppresses the detector offset to sub-μ T. Single 4.5-μ m magnetic beads are detected in 16 ms with a probability of error <; 0.1%.
Keywords :
CMOS integrated circuits; biosensors; calibration; electromagnets; error statistics; magnetic sensors; sampling methods; servomechanisms; CMOS implementation; baseline calibration; biomedical assays; correlated double sampling; detector offset suppression; embedded electromagnets; environmental variations; error probability; external magnet elimination; magnetic field modulation; magnetic label detector; magnetic relaxation detector; magnetic relaxation signature; microbead labels; offset servo loops; power dissipation reduction; reference sensors; relaxed dynamic range requirement; size 0.18 mum; Magnetic circuits; Magnetic moments; Magnetic resonance imaging; Magnetic sensors; Magnetic separation; Magnetometers; Biosensor; CMOS; magnetic bead; magnetic relaxation;
Journal_Title :
Solid-State Circuits, IEEE Journal of
DOI :
10.1109/JSSC.2012.2185339
