Integrated LTS gradiometer SQUID systems for measuring of magnetic field distributions in an unshielded environment

Supercond. Sci. Technol.

Weber

et al. 1999

A system for spatially resolved magnetorelaxometry in spatially expanded objects (e.g. for in vivo investigations) in a disturbed environment is presented. The system is based on an LTS SQUID gradiometer with a field gradient sensitivity of 30 fT cm-1 Hz-1/2 and an intrinsic balance of some 10-5. A Helmholtz coil of 80 cm diameter allows the magnetization of the samples with fields up to 7 mT. A nonmagnetic x-y stage (driven by step motors) covers a scanning area of 40 cm × 25 cm. We present spatially resolved measurements of the Néel relaxation of samples (dried ferrofluid) and compare them with model calculations. The data acquisition and monitoring as well as the filtering and fitting procedure are discussed.

Section: Realized Systemmentioning

confidence: 99%

LTS SQUID gradiometer system for in vivo magnetorelaxometry

Supercond. Sci. Technol.

Weber

et al. 1999

“…The chip dimensions were 5 mm × 10 mm. The gradiometer layouts and fabrication technology have already been described in [2].…”

Section: Gradiometer Layoutsmentioning

confidence: 99%

Integrated LTS gradiometer SQUID systems for unshielded measurements in a disturbed environment

Zakosarenko

Supercond. Sci. Technol.

et al. 1996

Various types of thin-film dc gradiometer SQUIDs with integrated pickup loops were investigated. The SQUIDs were prepared on a 5 mm × 10 mm chip in the well developed Nb-NbO x -Pb/Au/In technology. It was shown that the SQUIDs work in an unshielded environment. Our best SQUIDs have a field gradient sensitivity better then 30 fT cm −1 Hz −1/2 . All gradiometers have some response to a homogeneous field, i.e., a parasitic area. The effective pickup area, the field gradient sensitivity, and the components of the parasitic area for the field perpendicular and parallel to the gradiometer plane were measured for all types of gradiometer. The calculations of flux coupling efficiency are compared with experimental results. The origins of parasitic area are discussed. A further reduction of external disturbances was achieved by using an electronic second-order gradiometer. Examples of magnetocardiographic measurement in a physical laboratory without any shielding with first and second-order gradiometers are shown.

SQUID gradiometer measurement system for magnetorelaxometry in a disturbed environment

IEEE Trans. Appl. Supercond.

Weber

et al. 1999

Absfract-A SQUIDmeasurement system for magnetorelaxometry 0 in disturbed environment is presented. It was developed for the determination of the distribution of magnetic nanoparticles in large objects like animals. The system is based on a thin film LTS SQUID gradiometer with a baseline of 5 mm and a field gradient sensitivity of about 30 f'l'/cmWn. The entire system i s PC-controlled and includes a nonmagnetic x-y stage. A Helmholtz coil of 80 cm diameter allows the magnetization of the samples with fields up to 7 mT. First measurements in a disturbed environment are presented.