High resolution imaging of biomagnetic fields generated by action currents in cardiac tissue using a LTS-SQUID microscope

Baudenbacher, Franz; Peters, Nicholas; Baudenbacher, Petra; Wikswo, John P.

doi:10.1016/s0921-4534(01)01134-0

Cited by 20 publications

(12 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[75] Because our spring-loaded mechanism pushes the sample up against the sapphire window, the vertical distance between our sensor and sample, h, does not undergo the relatively high frequency jitter that the horizontal position experiences during scanning. We measure this distance by scanning a wire of known current (typically several mA) and fitting the field data for h [Baudenbacher et al, 2002b]. We have recently conducted a series of numerical experiments on simulated SM scans of wire with simulated horizontal position errors of 1 -10 mm.…”

Section: Discussionmentioning

confidence: 99%

Paleomagnetic analysis using SQUID microscopy

et al. 2007

View full text Add to dashboard Cite

[1] Superconducting quantum interference device (SQUID) microscopes are a new generation of instruments that map magnetic fields with unprecedented spatial resolution and moment sensitivity. Unlike standard rock magnetometers, SQUID microscopes map magnetic fields rather than measuring magnetic moments such that the sample magnetization pattern must be retrieved from source model fits to the measured field data. Here we present the first direct comparison between paleomagnetic analyses on natural samples using joint measurements from SQUID microscopy and moment magnetometry. We demonstrate that in combination with a priori geologic and petrographic data, SQUID microscopy can accurately characterize the magnetization of lunar glass spherules and Hawaiian basalt. The bulk moment magnitude and direction of these samples inferred from inversions of SQUID microscopy data match direct measurements on the same samples using moment magnetometry. In addition, these inversions provide unique constraints on the magnetization distribution within the sample. These measurements are among the most sensitive and highest resolution quantitative paleomagnetic studies of natural remanent magnetization to date. We expect that this technique will be able to extend many other standard paleomagnetic techniques to previously inaccessible microscale samples.

show abstract

Section: Discussionmentioning

confidence: 99%

Paleomagnetic analysis using SQUID microscopy

et al. 2007

View full text Add to dashboard Cite

show abstract

“…IX C 1͒ has also influenced the development of animal systems designed for in vitro measurements. 144…”

Section: Animal Systemsmentioning

confidence: 99%

Superconducting quantum interference device instruments and applications

Fagaly¹

2006

Review of Scientific Instruments

476

267

View full text Add to dashboard Cite

Superconducting quantum interference devices ͑SQUIDs͒ have been a key factor in the development and commercialization of ultrasensitive electric and magnetic measurement systems. In many cases, SQUID instrumentation offers the ability to make measurements where no other methodology is possible. We review the main aspects of designing, fabricating, and operating a number of SQUID measurement systems. While this article is not intended to be an exhaustive review on the principles of SQUID sensors and the underlying concepts behind the Josephson effect, a qualitative description of the operating principles of SQUID sensors and the properties of materials used to fabricate SQUID sensors is presented. The difference between low and high temperature SQUIDs and their suitability for specific applications is discussed. Although SQUID electronics have the capability to operate well above 1 MHz, most applications tend to be at lower frequencies. Specific examples of input circuits and detection coil configuration for different applications and environments, along with expected performance, are described. In particular, anticipated signal strength, magnetic field environment ͑applied field and external noise͒, and cryogenic requirements are discussed. Finally, a variety of applications with specific examples in the areas of electromagnetic, material property, nondestructive test and evaluation, and geophysical and biomedical measurements are reviewed.

show abstract

“…1,2 In addition to the SQUID's unsurpassed field sensitivity, this technique is completely non-invasive and can be implemented to study a great variety of samples. RT sample SSM is continuing to play an important role in biomagnetism, [3][4][5][6][7][8] nondestructive evaluation, [9][10][11][12][13][14] and geomagnetism. 15,16 Since the field and spatial resolution are highly diminished as the distance between the sample and the sensor increases, the key to this technique is to bring the sensor, held at cryogenic temperatures, as close as possible to the sample.…”

Section: Introductionmentioning

confidence: 99%

High-resolution room-temperature sample scanning superconducting quantum interference device microscope configurable for geological and biomagnetic applications

Fong¹,

Holzer²,

McBride³

et al. 2005

Review of Scientific Instruments

Self Cite

View full text Add to dashboard Cite

We have developed a scanning superconducting quantum interference device ͑SQUID͒ microscope system with interchangeable sensor configurations for imaging magnetic fields of room-temperature ͑RT͒ samples with submillimeter resolution. The low-critical-temperature ͑T c ͒ niobium-based monolithic SQUID sensors are mounted on the tip of a sapphire and thermally anchored to the helium reservoir. A 25 m sapphire window separates the vacuum space from the RT sample. A positioning mechanism allows us to adjust the sample-to-sensor spacing from the top of the Dewar. We achieved a sensor-to-sample spacing of 100 m, which could be maintained for periods of up to four weeks. Different SQUID sensor designs are necessary to achieve the best combination of spatial resolution and field sensitivity for a given source configuration. For imaging thin sections of geological samples, we used a custom-designed monolithic low-T c niobium bare SQUID sensor, with an effective diameter of 80 m, and achieved a field sensitivity of 1.5 pT/ Hz 1/2 and a magnetic moment sensitivity of 5.4ϫ 10 −18 A m 2 /Hz 1/2 at a sensor-to-sample spacing of 100 m in the white noise region for frequencies above 100 Hz. Imaging action currents in cardiac tissue requires a higher field sensitivity, which can only be achieved by compromising spatial resolution. We developed a monolithic low-T c niobium multiloop SQUID sensor, with sensor sizes ranging from 250 m to 1 mm, and achieved sensitivities of 480-180 fT/ Hz 1/2 in the white noise region for frequencies above 100 Hz, respectively. For all sensor configurations, the spatial resolution was comparable to the effective diameter and limited by the sensor-to-sample spacing. Spatial registration allowed us to compare high-resolution images of magnetic fields associated with action currents and optical recordings of transmembrane potentials to study the bidomain nature of cardiac tissue or to match petrography to magnetic field maps in thin sections of geological samples.

show abstract

High resolution imaging of biomagnetic fields generated by action currents in cardiac tissue using a LTS-SQUID microscope

Cited by 20 publications

References 8 publications

Paleomagnetic analysis using SQUID microscopy

Paleomagnetic analysis using SQUID microscopy

Superconducting quantum interference device instruments and applications

High-resolution room-temperature sample scanning superconducting quantum interference device microscope configurable for geological and biomagnetic applications

Contact Info

Product

Resources

About