Regensburg 2013 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 49: Superconductivity: SQUIDs & Cryodetectors
TT 49.5: Talk
Wednesday, March 13, 2013, 18:00–18:15, H21
MRX Measurement Setup Employing a Directly-Coupled High-Tc SQUID With Slotted Pickup Loop — •Alexander Guillaume, Frank Ludwig, Jan M. Scholtyssek, and Meinhard Schilling — Institut für Elektrische Messtechnik und Grundlagen der Elektrotechnik, Technische Universität Braunschweig, Hans-Sommer-Str. 66, D-38106 Braunschweig, Germany
Magnetic nanoparticles (MNP) are employed in a wide range of medical and industrial applications. Besides other characterization techniques, magnetorelaxometry (MRX) is well established. In our MRX setup, we employ a directly-coupled high-Tc SQUID with a slotted pickup loop as magnetic field sensor.
The whole setup is installed in a magnetically shielded room. The MNP sample, which is attached to a glass dipstick containing the SQUID, is magnetized by a pair of Helmholtz-coils. In order to prevent flux vortices from entering the SQUID, the sensor is aligned parallel to the magnetizing field so that only the stray field of the MNP is measured. The aligning process is accomplished by using three alignment screws. Hence, the SQUID only measures 1 ppm of the magnetizing field which is in the order of several mT. Since the magnetic nanoparticles are placed in liquid nitrogen, the relaxation time constant increases in comparison to a measurement of the particles at room temperature allowing to investigate particle sizes down to 10 nm.
Here, we present our MRX setup and the employed SQUID design. We evaluate its performace by carrying out MRX measurements on immobilized MNPs.