Modular Middle-Scale SQUID Magnetometer System for Neuromagnetic Research (Special Issue on Toward Digital and Analog Applications of Superconductors)

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概要

• 論文の詳細を見る

• 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 consists of Nb/A1-oxide/Nb SQUlD 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 25 L 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^<2/1> at l0-100 Hz and below 18fT/Hz^<2/1> at l-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 fTpp. The isofield contours of the peak response showed that the measurement area is L large enough to estimate current dipoles. It is confirmed that the system has the ability to measure magnetic fields from the human brain.

• 社団法人電子情報通信学会の論文
• 1996-09-25

著者

• Kuriki S

  Research Institute For Electronic Science Hokkaido University

• HIRATA Yoshihiro

  the Research Institute for Electronic Science, Hokkaido University

• KURIKI Shinya

  the Research Institute for Electronic Science, Hokkaido University

• Hirata Y

  The Research Institute For Electronic Science Hokkaido University

• Hirata Yoshihiro

  The Research Institute For Electronic Science Hokkaido University

関連論文

• Development of a High-T_c SQUID-Based Magnetometer System for MCG Measurement(Special Issue on Superconductive Electronics)
• Single-Layer High-T_c Superconducting Quantum lnterference Device Magnetometer with Double-Pickup-Coil Configuration
• Flux Coupling in the Direct-Coupled High-T_c Superconducting Quantum Interference Devices
• First Derivative High-Tc SQUID Gradiometers with Narrow Structure from Single Layer YBCO Thin Film(Special Issue on Superconductive Electronics)
• On the AC Bias Readout Schemes for High-T_C Superconducting Quantum Interference Devices
• Modular Middle-Scale SQUID Magnetometer System for Neuromagnetic Research (Special Issue on Toward Digital and Analog Applications of Superconductors)
• Effects of Damping Resistance on the Modulation Voltage of Large-Inductance High-T_c Superconducting Quantum Interference Devices
• Modulation Voltage and Flux Noise in High-T_c Grain Boundary Junction Superconducting Quantum Interference Devices
• Magnetocrystalline and Uniaxial Anisotropy Epitaxial (110) Ni-Fe Thin Films

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