Bead magnetorelaxometry with an on-chip magnetoresistive sensor.
Magnetorelaxometry measurements on suspensions of magnetic beads are demonstrated using a planar Hall effect sensor chip embedded in a microfluidic system. The alternating magnetic field used for magnetizing the beads is provided by the sensor bias current and the complex magnetic susceptibility spectra are recorded as the 2nd harmonic of the sensor response. The complex magnetic susceptibility signal appears when a magnetic bead suspension is injected, it scales with the bead concentration, and it follows the Cole-Cole expression for Brownian relaxation. The complex magnetic susceptibility signal resembles that from conventional magnetorelaxometry done on the same samples apart from an offset in Brownian relaxation frequency. The time dependence of the signal can be rationalized as originating from sedimented beads.
Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech, Building 345 East, 2800, Kgs. Lyngby, Denmark.
Bjarke Thomas
BT
Dalslet
Christian Danvad
CD
Damsgaard
Marco
M
Donolato
Maria
M
Strømme
Mattias
M
Strömberg
Peter
P
Svedlindh
Mikkel Fougt
MF
Hansen
D004867:Equipment Design; D008280:Magnetics / Q000295:instrumentation*; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D008863:Microspheres; D013535:Suspensions / Q000032:analysis
D013535:Suspensions