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

Volume

47

Issue

4

fYear

2012

fDate

4/1/2012 12:00:00 AM

Firstpage

1056

Lastpage

1064

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;

fLanguage

English

Journal_Title

Solid-State Circuits, IEEE Journal of

Publisher

ieee

ISSN

0018-9200

Type

jour

DOI

10.1109/JSSC.2012.2185339

Filename

6158617