A 7-Channel High-T-c SQUID-Based On-Scalp MEG System
Journal article, 2020

Objective: To present the technical design and demonstrate the feasibility of a multi-channel on-scalp magnetoencephalography (MEG) system based on high critical temperature (high-Tc) superconducting quantum interference devices (SQUIDs).
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.

high-T-c SQUID

Magnetoencephalography (MEG)

on-scalp MEG

multichannel system

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)

Vol. 67 5 1483-1489

Subject Categories

Computer Engineering

Medical Laboratory and Measurements Technologies

Other Electrical Engineering, Electronic Engineering, Information Engineering

DOI

10.1109/TBME.2019.2938688

PubMed

31484107

More information

Latest update

9/9/2020 1