First results for a novel superconducting imaging-surface sensor array

Kraus, R.H.; Flynn, E.R.; Espy, Michelle A.; Matlashov, Andrei; Overton, W.C.; Peters, M.; Ruminer, P.

doi:10.1109/77.783643

Cited by 5 publications

(7 citation statements)

References 6 publications

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“…As in the case of MEG systems, some innovative proposals have been introduced with the aim at simplifying the system design and thus reducing the related costs and improving the information obtained by recording of the magnetic field. Promising preliminary results obtained with a flat 12-channel system based on a superconducting imaging surface have been presented [108]. The basics of system operation are similar to the concepts described for the helmet system in section 7.1.1; with this method virtual axial gradiometers are determined by the effect of the superconducting surface, thus avoiding fabrication and balancing costs.…”

Section: 13mentioning

confidence: 93%

“…Moreover, the superconducting surface acts as shielding for the near sensors, deviating the magnetic field generated by far sources, thus requiring a low-quality shielded room for proper operation. A whole-head system comprising 155 dcSQUID integrated magnetometers and a hemispherical imaging surface made of lead is being developed [107]. The sensors are dcSQUID integrated magnetometers [108]; due to the different geometry of the superconducting and measurement surfaces, the resulting gradiometers have different baselines.…”

Section: Multichannel Systems For Megmentioning

confidence: 99%

“…A whole-head system comprising 155 dcSQUID integrated magnetometers and a hemispherical imaging surface made of lead is being developed [107]. The sensors are dcSQUID integrated magnetometers [108]; due to the different geometry of the superconducting and measurement surfaces, the resulting gradiometers have different baselines. From preliminary measurements with ten channels installed in the SQUID support to characterize the system, the magnetic field noise was about 10 fT Hz −1/2 in a shielded room and 1 pT Hz −1/2 out of a shielded room.…”

Section: Multichannel Systems For Megmentioning

confidence: 99%

See 2 more Smart Citations

SQUID systems for biomagnetic imaging

Pizzella

Penna

Gratta

et al. 2001

Supercond. Sci. Technol.

110

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This review paper illustrates the different SQUID based systems used for biomagnetic imaging. The review is divided into nine sections. The first three sections are introductory: section 1 is a short overview of the topic; section 2 summarizes how the biomagnetic fields are generated and what are the basic mathematical models for the field sources; section 3 illustrates the principles of operation of the SQUID device. Sections 4-8 are specifically devoted to the description of the different systems used for biomagnetic measurements: section 4 discusses the different types of detection coils; section 5 illustrates the SQUID sensors specifically designed for biomagnetic applications together with the necessary driving electronics, with special emphasis on high-temperature superconductivity (HTS) SQUIDs, since HTS devices are still in a developing stage; section 6 illustrates the different noise reduction techniques; section 7 describes the different multichannel sensors presently operating; and, finally, section 8 gives a hint of what kind of physiological and/or clinical information may be gathered by the biomagnetic technique. Section 9 suggests some future trends for the biomagnetic technique.

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Section: 13mentioning

confidence: 93%

Section: Multichannel Systems For Megmentioning

confidence: 99%

Section: Multichannel Systems For Megmentioning

confidence: 99%

See 1 more Smart Citation

SQUID systems for biomagnetic imaging

Pizzella

Penna

Gratta

et al. 2001

Supercond. Sci. Technol.

110

View full text Add to dashboard Cite

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“…The other is a magnetoencephalography system using 155 SQUID magnetometers and a lead hemispherical S1S of radius 11 cm. Tests of these systems indicated that when the SQUIDS were near the center of the S1S they dld behave primarily as gra&ometers [2].…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of high temperature superconducting imaging surface magnetometry

Espy

Matlashov

Kraus

et al. 2002

Review of Scientific Instruments

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“…low signal-to-noise, cost, bulk). The Los Alamos SIS-MEG system [3] is based on the principal that Meissner currents flow in the surface of superconductors, preventing any significant penetration of magnetic fields. A hemispherical SIS with a brim, or helmet, surrounds the SQUID sensors largely shielding them from sources outside the helmet while measuring fields from nearby sources within the helmet.…”

Section: Introductionmentioning

confidence: 99%

Performance of a novel SQUID-based superconducting imaging-surface magnetoencephalography system

Kraus

Volegov

Maharajh

et al. 2002

Physica C: Superconductivity

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Abstract-Performance for a recently completed whole-head magnetoencephalography system using a superconducting imaging-surface (SIS) surrounding an array of 150 SQUID magnetometers is reported. The helmetlike SIS is hemispherical in shape with a brim. Conceptually, the SIS images nearby sources onto the SQUIDs while shielding sensors from distant "noise" sources. A finite element method (FEM) description using the as-built geometry was developed to describe the SIS effect on source fields by imposing B ⊥ (surface)=0. Sensors consist of 8mm × 8mm SQUID magnetometers with 0.84nT/Φ sensitivity and <3fT/√Hz noise. A series of phantom experiments to verify system efficacy have been completed. Simple dry-wire phantoms were used to eliminate model dependence from our results. Phantom coils were distributed throughout the volume encompassed by the array with a variety of orientations. Each phantom coil was precisely machined and located to better than 25µm and 10mRad accuracy. Excellent agreement between model-calculated and measured magnetic field distributions of all phantom coil positions and orientations was found. Good agreement was found between modeled and measured shielding of the SQUIDs from sources external to the array showing significant frequency-independent shielding. Phantom localization precision was better than 0.5mm at all locations with a mean of better than 0.3mm. IntroductionWeak magnetic fields are a direct consequence of neuronal activity in the brain that causes ionic currents to flow in the neurons [1]. Magnetoencephalography (MEG) is the technique that measures the weak magnetic fields that emanate from the brain[2] as a direct consequence of the neuronal currents resulting from brain activity. The extraordinarily weak magnetic fields, typically 10-100 femtoTesla (fT), are measured by an array of SQUID (Superconducting QUantum Interference Device) sensors. The position and vector characteristics of these neuronal sources can be estimated from the inverse solution of the field distribution at the surface of the head. In addition to locating the sources of neuronal activity, MEG temporal resolution is unsurpassed by any other method currently used for brain imaging. Although MEG is not truly tomographic and source reconstruction is limited by solutions of the electromagnetic inverse problem, constraints used for source localization produce reliable and accurate results. Current MEG instrumental source location accuracy reported in the literature is approximately 2 to 4 mm, depending on source parameters, and typically 5-10 mm accuracy is attained in most medical applications with the latest instruments.A unique whole-head MEG system incorporating a superconducting imaging-surface (SIS) has been designed and built at Los Alamos with the goal of dramatically improving source localization accuracy while mitigating limitations of current systems (e.g. low signal-to-noise, cost, bulk). The Los Alamos SIS-MEG system[3] is based on the principal that Meissner currents flow in the surface of superconduc...

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First results for a novel superconducting imaging-surface sensor array

Cited by 5 publications

References 6 publications

SQUID systems for biomagnetic imaging

SQUID systems for biomagnetic imaging

Experimental investigation of high temperature superconducting imaging surface magnetometry

Performance of a novel SQUID-based superconducting imaging-surface magnetoencephalography system

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