Modular Middle-Scale SQUID Magnetometer System for Neuromagnetic Research

Yoshihiro HIRATA; Shinya KURIKI

Modular Middle-Scale SQUID Magnetometer System for Neuromagnetic Research

Yoshihiro HIRATA, Shinya KURIKI

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A new 19-channel SQUID magnetometer system has been developed for research use in order to measure the neuromagnetic fields originating from cortices of the human brain.The system could function for 6 days with a one-time supply of about 25 L of liquid helium. The system consists of Nb/Al-oxide/Nb SQUID sensors with 2nd-order gradiometers, tank circuits, readout electronics, a liquid helium dewar, a gantry, and a prefabricated shielded room. The gradiometers cover a circular area of 15 cm radius. We used fine stainless steel leads for electric connection between the sensors and room-temperature electronics with low thermal conduction in a low helium consumption dewar. The system could function for 6 days with a one-time supply of about 25L of liquid helium. The system can be thermally cycled for repeated measurements, with an intervening nonusage period at room temperature. The noise characteristics, for both the time and frequency domains, of all channels were measured. From an analysis of the voltage output at the phase-sensitive detector, the flux-origin noise which is generated by external sources was dominant in the white noise frequency. The power spectra of the noise field were below 10 fT/Hz^1/2 at 10-100 Hz and below 18 fT/Hz^1/2 at 1-10 Hz. Some other peaks of power line frequencies such as 50 Hz and 150 Hz were observed at several channels. Sound-evoked magnetic fields were measured from the temporal area of the head upon application of tone bursts. The evoked fields were recorded with the amplitude of about 250 fT_pp. The isofield contours of the peak response showed that the measurement area is large enough to estimate current dipoles. It is confirmed that the system has the ability to measure magnetic fields from the human brain.

Publication: IEICE TRANSACTIONS on Electronics Vol.E79-C No.9 pp.1213-1218

Publication Date: 1996/09/25

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Type of Manuscript: Special Section INVITED PAPER (Special Issue on Toward Digital and Analog Applications of Superconductors)

Category: Analog applications

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Yoshihiro HIRATA, Shinya KURIKI, "Modular Middle-Scale SQUID Magnetometer System for Neuromagnetic Research" in IEICE TRANSACTIONS on Electronics, vol. E79-C, no. 9, pp. 1213-1218, September 1996, doi: .
Abstract: A new 19-channel SQUID magnetometer system has been developed for research use in order to measure the neuromagnetic fields originating from cortices of the human brain.The system could function for 6 days with a one-time supply of about 25 L of liquid helium. The system consists of Nb/Al-oxide/Nb SQUID sensors with 2nd-order gradiometers, tank circuits, readout electronics, a liquid helium dewar, a gantry, and a prefabricated shielded room. The gradiometers cover a circular area of 15 cm radius. We used fine stainless steel leads for electric connection between the sensors and room-temperature electronics with low thermal conduction in a low helium consumption dewar. The system could function for 6 days with a one-time supply of about 25L of liquid helium. The system can be thermally cycled for repeated measurements, with an intervening nonusage period at room temperature. The noise characteristics, for both the time and frequency domains, of all channels were measured. From an analysis of the voltage output at the phase-sensitive detector, the flux-origin noise which is generated by external sources was dominant in the white noise frequency. The power spectra of the noise field were below 10 fT/Hz^1/2 at 10-100 Hz and below 18 fT/Hz^1/2 at 1-10 Hz. Some other peaks of power line frequencies such as 50 Hz and 150 Hz were observed at several channels. Sound-evoked magnetic fields were measured from the temporal area of the head upon application of tone bursts. The evoked fields were recorded with the amplitude of about 250 fT_pp. The isofield contours of the peak response showed that the measurement area is large enough to estimate current dipoles. It is confirmed that the system has the ability to measure magnetic fields from the human brain.
URL: https://globals.ieice.org/en_transactions/electronics/10.1587/e79-c_9_1213/_p

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@ARTICLE{e79-c_9_1213,
author={Yoshihiro HIRATA, Shinya KURIKI, },
journal={IEICE TRANSACTIONS on Electronics},
title={Modular Middle-Scale SQUID Magnetometer System for Neuromagnetic Research},
year={1996},
volume={E79-C},
number={9},
pages={1213-1218},
abstract={A new 19-channel SQUID magnetometer system has been developed for research use in order to measure the neuromagnetic fields originating from cortices of the human brain.The system could function for 6 days with a one-time supply of about 25 L of liquid helium. The system consists of Nb/Al-oxide/Nb SQUID sensors with 2nd-order gradiometers, tank circuits, readout electronics, a liquid helium dewar, a gantry, and a prefabricated shielded room. The gradiometers cover a circular area of 15 cm radius. We used fine stainless steel leads for electric connection between the sensors and room-temperature electronics with low thermal conduction in a low helium consumption dewar. The system could function for 6 days with a one-time supply of about 25L of liquid helium. The system can be thermally cycled for repeated measurements, with an intervening nonusage period at room temperature. The noise characteristics, for both the time and frequency domains, of all channels were measured. From an analysis of the voltage output at the phase-sensitive detector, the flux-origin noise which is generated by external sources was dominant in the white noise frequency. The power spectra of the noise field were below 10 fT/Hz^1/2 at 10-100 Hz and below 18 fT/Hz^1/2 at 1-10 Hz. Some other peaks of power line frequencies such as 50 Hz and 150 Hz were observed at several channels. Sound-evoked magnetic fields were measured from the temporal area of the head upon application of tone bursts. The evoked fields were recorded with the amplitude of about 250 fT_pp. The isofield contours of the peak response showed that the measurement area is large enough to estimate current dipoles. It is confirmed that the system has the ability to measure magnetic fields from the human brain.},
keywords={},
doi={},
ISSN={},
month={September},}

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TY - JOUR
TI - Modular Middle-Scale SQUID Magnetometer System for Neuromagnetic Research
T2 - IEICE TRANSACTIONS on Electronics
SP - 1213
EP - 1218
AU - Yoshihiro HIRATA
AU - Shinya KURIKI
PY - 1996
DO -
JO - IEICE TRANSACTIONS on Electronics
SN -
VL - E79-C
IS - 9
JA - IEICE TRANSACTIONS on Electronics
Y1 - September 1996
AB - A new 19-channel SQUID magnetometer system has been developed for research use in order to measure the neuromagnetic fields originating from cortices of the human brain.The system could function for 6 days with a one-time supply of about 25 L of liquid helium. The system consists of Nb/Al-oxide/Nb SQUID sensors with 2nd-order gradiometers, tank circuits, readout electronics, a liquid helium dewar, a gantry, and a prefabricated shielded room. The gradiometers cover a circular area of 15 cm radius. We used fine stainless steel leads for electric connection between the sensors and room-temperature electronics with low thermal conduction in a low helium consumption dewar. The system could function for 6 days with a one-time supply of about 25L of liquid helium. The system can be thermally cycled for repeated measurements, with an intervening nonusage period at room temperature. The noise characteristics, for both the time and frequency domains, of all channels were measured. From an analysis of the voltage output at the phase-sensitive detector, the flux-origin noise which is generated by external sources was dominant in the white noise frequency. The power spectra of the noise field were below 10 fT/Hz^1/2 at 10-100 Hz and below 18 fT/Hz^1/2 at 1-10 Hz. Some other peaks of power line frequencies such as 50 Hz and 150 Hz were observed at several channels. Sound-evoked magnetic fields were measured from the temporal area of the head upon application of tone bursts. The evoked fields were recorded with the amplitude of about 250 fT_pp. The isofield contours of the peak response showed that the measurement area is large enough to estimate current dipoles. It is confirmed that the system has the ability to measure magnetic fields from the human brain.
ER -