Magnetorelaxometry of magnetic nanoparticles in magnetically unshielded environment utilizing a differential fluxgate arrangement

Abstract

A magnetorelaxometry system based on a differential fluxgate arrangement is presented. Compared to the single fluxgate setup, the use of two fluxgate magnetometers increases the relaxation signal from the sample by a factor of 2, the signal-to-noise ratio by a factor 2, and allows one to perform magnetorelaxation measurements without any magnetic shielding. For a sample with superparamagnetic Fe3O4 nanoparticles and a volume of 150μl, 100 nmol Fe could be detected, limited by the intrinsic noise of the fluxgate sensors.

Fluxgate magnetorelaxometry of superparamagnetic nanoparticles for hydrogel characterization

“…The net magnetization of the MNPs in the hydrogel is measured with our differential fluxgate MRX system [9]. Since two fluxgates are oriented with their sensitive axes perpendicularly to the magnetization field, only the stray field of the sample is detected, which is a measure of the magnetization of the sample.…”

Magnetic relaxometry as applied to sensitive cancer detection and localization

“…Localization of the NP sources can then be performed by fitting a dipolar model [10,12] to the acquired data using a quasi-static approximation. More recently, fluxgate sensors [17] and atomic magnetometers [7,14,15] have also been employed for sensitive detection of magnetic fields in SPMR experiments. Incorporation of gradiometers allow fields from distant sources to be cancelled, thus making it possible for SPMR measurements to be performed in unshielded environments.…”

Characterization of energy barrier and particle size distribution of lyophilized ferrofluids by magnetic relaxation measurements

“…Clinic magnetic resonance imaging (MRI) systems can detect a concentration of ferromagnetic iron of about 0.01 mg Fe/ml [11]. With fluxgate arrangements it is possible to reach the region of 100 nmol Fe in a volume of 0.15 ml [12]. The great advantage of these systems is the operation at room temperature.…”