Multichannel DC SQUID sensor array for biomagnetic applications

A biomagnetic multichannel system for medical diagnosis of the brain and heart has been developed. 37 axial first order gradiometers (manufactured as flexible superconducting printed circuits) are arranged in a circular flat array of 19 cm in diameter. Additionally, three orthogonal magnetometers are provided. The DC SQUIDs are fabricated in all-Nb technology, ten on a chip. The sensor system is operated in a shielded room with two layers of soft magnetic material and one layer of Al. The everyday noise level is 10 fT/Hz/sup 1/2/ at frequencies above 10 Hz. Within two years of operation in a normal urban surrounding, useful clinical applications have been demonstrated (e.g., for epilepsy and heart arrhythmias). For the first time current sources of sporadic events causing epilepsy or ventricular extrasystoles have been localized from coherent recordings of complete biomagnetic field distributions with spatial resolution of millimeters and temporal resolution of 1 ms.

[1]  T. Katila.  Principles and Applications of SQUID Sensors , 1989 .

[2]  F. Wellstood,et al.  Low magnetic flux noise observed in laser-deposited in situ films of YB2Cu3Oy and implications for high- Tc SQUIDs , 1989, Nature.

[3]  John Clarke,et al.  Tunnel junction dc SQUID: Fabrication, operation, and performance , 1976 .

[4]  R. Fenici,et al.  Atrial and Ventricular Tachycardias: Invasive validation and reproducibility of magnetocardiographic imaging , 1989 .

[5]  Helmut Dipl Phys Reichenberger,et al.  Biomagnetic multichannel system with integrated SQUIDs and first order gradiometers operating in a shielded room , 1989 .

[6]  Gian Luca Romani,et al.  Fundamentals on Neuromagnetism , 1989 .

[7]  J Beatty,et al.  Neuromagnetic evidence of spatially distributed sources underlying epileptiform spikes in the human brain. , 1984, Science.

[8]  Klaus Abraham-Fuchs,et al.  Development and Performance of a Multichannel System for Studies of Biomagnetic Signals of Brain and Heart , 1989 .

[9]  A. Ioannides,et al.  Localised and Distributed Source Solutions for the Biomagnetic Inverse Problem II , 1989 .

[10]  K. Abraham-Fuchs,et al.  Multichannel biomagnetic system for study of electrical activity in the brain and heart. , 1990, Radiology.

[11]  Mark B. Ketchen,et al.  Planar coupling scheme for ultra low noise DC SQUIDs , 1981 .

[12]  D. Cohen,et al.  MAGNETOCARDIOGRAMS TAKEN INSIDE A SHIELDED ROOM WITH A SUPERCONDUCTING POINT‐CONTACT MAGNETOMETER , 1970 .

[13]  John P. Wikswo.  Biomagnetic Sources and Their Models , 1989 .

[14]  R. Ilmoniemi,et al.  A 24-Channel Magnetometer for Brain Research , 1989 .

[15]  K. Abraham-Fuchs,et al.  MCG inverse solution: influence of coil size, grid size, number of coils, and SNR , 1988, IEEE Transactions on Biomedical Engineering.

[16]  W W Sutherling,et al.  Neocortical propagation in temporal lobe spike foci on magnetoencephalography and electroencephalography , 1989, Annals of neurology.

[17]  Mark B. Ketchen,et al.  Ultra‐low‐noise tunnel junction dc SQUID with a tightly coupled planar input coil , 1982 .

[18]  J. Clem.  Johnson noise from normal metal near a superconducting SQUID gradiometer circuit , 1987 .