Biomagnetic measurement system for supine subjects with expanded sensor array and real-time noise reduction

Area of Science:

• Biophysics
• Biomedical Engineering
• Neuroscience

Background:

• Biomagnetic signals like magnetospinogram (MSG) and magnetocardiogram (MCG) offer noninvasive insights into physiological electrical activity.
• Detecting these extremely weak signals requires highly sensitive superconducting quantum interference devices (SQUIDs).
• Ultra-low frequency environmental noise, particularly from urban transportation, severely impedes sensitive magnetic field measurements.

Purpose of the Study:

• To develop a biomagnetic measurement system capable of detecting both MSG and MCG signals.
• To mitigate ultra-low frequency environmental noise affecting SQUID-based measurements.
• To enhance the signal-to-noise ratio for improved diagnostic capabilities.

Main Methods:

• Development of a biomagnetic measurement system for detecting MSG and MCG from supine subjects.
• Implementation of reference sensors to monitor environmental magnetic noise.
• Integration of noise-canceling feedback mechanisms using weighted coefficients into a SQUID gradiometer's feedback coil.

Main Results:

• A reduction in ultra-low frequency noise by approximately 90% was achieved through synthesized in-phase components.
• Successful detection of both MSG and MCG signals was demonstrated in a moderately shielded room.
• Significant improvement in the signal-to-noise ratio was observed, even when MCG signals overlapped with low-frequency noise.

Conclusions:

• The developed biomagnetic system effectively detects spinal cord and heart activity noninvasively.
• The noise reduction technique significantly enhances the feasibility of biomagnetic measurements in noisy environments.
• This advancement holds promise for improved diagnostic tools in neurology and cardiology.