Sensitivity and spatial resolution of square loop SQUID magnetometers

Rombetto, S.; Vettoliere, A.; Granata, C.; Russo, M.; Nappi, C.

doi:10.1016/j.physc.2008.08.005

Cited by 4 publications

(2 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For our estimates, we used the SNR obtained with the calibrator sources at a working frequency of 8009 Hz. Theoretically, for simple geometries of the detection channel, it would be possible to calculate the minimum detectable magnetic dipole as a function of the distance and orientation between the pick-up coil and the magnetic source, once the intrinsic noise of the channel is known [20]. As an example, for a magnetometer, the magnetic flux scales as a function of the pick-up area, the flux gain G Φ decreases when increasing the size of the pick-up loop whereas the noise is increased by the same factor G Φ .…”

Section: Comparison Between the Sensitivity Of The Superconducting Domentioning

confidence: 99%

NMR Detection at 8.9 Mt With a GMR Based Sensor Coupled to a Superconducting Nb Flux Transformer

Sinibaldi¹,

Luca²,

Nieminen³

et al. 2013

PIER

View full text Add to dashboard Cite

Abstract-This study presents NMR signal detection by means of a superconducting channel consisting of a Nb surface detection coil inductively coupled to a YBCO mixed sensor. The NMR system operates at a low-field (8.9 mT) in a magnetically shielded room suitable for magnetoencephalographic (MEG) recordings. The main field is generated by a compact solenoid and the geometry of the pick-up coil has been optimized to provide high spatial sensitivity in the NMR field of view. The Nb detection coil is coupled to the mixed sensor through a Nb input coil. The mixed sensor consists of a superconducting YBCO loop with 2-µm constriction above which two Giant MagnetoResistance sensors are placed in a half-bridge configuration to detect changes of the bridge voltage as a function of the flux through the YBCO loop. The sensitivity of the receiving channel is calibrated experimentally. The measured spatial sensitivity is in agreement with the simulations and is ∼10 times better than that of the stand-alone mixed sensor. A NMR echo at 375 kHz shows a SNR only a factor 4 smaller than a tuned room temperature coil tightly wound around the sample, with a noise level which is a factor 3 better than for the volume coil. Our results suggest that mixed sensors are suitable for the integration of low-field MRI and MEG in a hybrid apparatus, where MEG and MRI would be recorded by SQUIDs and mixed sensors, respectively.

show abstract

Section: Comparison Between the Sensitivity Of The Superconducting Domentioning

confidence: 99%

NMR Detection at 8.9 Mt With a GMR Based Sensor Coupled to a Superconducting Nb Flux Transformer

Sinibaldi¹,

Luca²,

Nieminen³

et al. 2013

PIER

View full text Add to dashboard Cite

show abstract

“…Numerical evaluation of the integral for φ is straightforward and has the advantage that more complex loop geometries can be considered relatively easily. Note, however, that the flux coupled to a filamentary square or circular loop from a point dipole can be expressed analytically [27,38,39].…”

Section: Flux Coupled To a Nanosquid From A Nearby Magnetic Momentmentioning

confidence: 99%

NanoSQUID detection of magnetization from ferritin nanoparticles

Vohralik

Lam

2009

Supercond. Sci. Technol.

View full text Add to dashboard Cite

A gold-shunted Nb nanoSQUID (SQUID: superconducting quantum interference device) operated in open-loop current-biased mode has been used to measure flux changes in the presence of nearby nanoparticles of native horse-spleen ferritin (magnetic moment μ 300μ B ). The ferritin nanoparticles were attached to one of the nanobridge junctions using appropriately functionalized organic linker molecules. Calculations of the coupling between an idealized nanoSQUID and a nearby ferritin magnetic moment are used to illustrate the dependence of the coupled flux on the nanoparticle-nanoSQUID separation and the dimensions of the SQUID loop. Flux changes calculated for the reversal of a ferritin magnetic moment coupled to the nanoSQUID are consistent with some, but not all, of the measured flux changes. Further studies are needed to determine the mechanisms involved.

show abstract