A 7-Channel High-T-c SQUID-Based On-Scalp MEG System
Journal article, 2020
Methods: We built a liquid nitrogen-cooled cryostat that houses seven YBCO SQUID magnetometers arranged in a dense, head-aligned array with minimal distance to the room-temperature environment for all sensors. We characterize the performance of this 7-channel system in terms of on-scalp MEG utilization and present recordings of spontaneous and evoked brain activity.
Results: The center-to-center spacing between adjacent SQUIDs is 12.0 and 13.4 mm and all SQUIDs are in the range of 1-3 mm of the head surface. The cryostat reaches a base temperature of 70 K and stays cold for >16hwith a single 0.9 L filling. The white noise levels of the magnetometers is 50-130 fT/Hz1/2 at 10 Hz and they show low sensor-tosensor feedback flux crosstalk (<0.6%). We demonstrate evoked fields fromauditory stimuli and single-shot sensitivity to alpha modulation from the visual cortex.
Conclusion: All seven channels in the system sensitively sample neuromagnetic fields with mm-scale scalp standoff distances. The hold time of the cryostat furthermore is sufficient for a day of recordings. As such, our multi-channel high-Tc SQUID-based system meets the demands of on-scalp MEG. Significance: The system presented here marks the first high-Tc SQUID-based on-scalp MEG system with more than two channels. It enables us to further explore the benefits of on-scalp MEG in future recordings.
Magnetoencephalography (MEG)
on-scalp MEG
multichannel system
high-T-c SQUID
Author
Christoph Pfeiffer
Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics
Silvia Ruffieux
Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics
Lars Jönsson
Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics
Maxim L. Chukharkin
Stiftelsen Chalmers Industriteknik
Alexei Kalaboukhov
Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics
Minshu Xie
Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics
Dag Winkler
Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics
Justin F. Schneiderman
University of Gothenburg
IEEE Transactions on Biomedical Engineering
0018-9294 (ISSN) 15582531 (eISSN)
Vol. 67 5 1483-1489 8821327Subject Categories
Computer Engineering
Medical Laboratory and Measurements Technologies
Other Electrical Engineering, Electronic Engineering, Information Engineering
Condensed Matter Physics
DOI
10.1109/TBME.2019.2938688
PubMed
31484107