Performance Evaluation of a Diamond Quantum Magnetometer for Biomagnetic Sensing: A Phantom Study

TL;DR

This study assesses a diamond quantum magnetometer's ability to detect brain-like magnetic signals using a phantom model, demonstrating high sensitivity and spatial resolution suitable for biomagnetic applications.

Contribution

It provides a practical evaluation of a diamond quantum magnetometer's performance in biomagnetic sensing using a phantom, highlighting its potential for detecting brain activity signals.

Findings

Sensitivity of about 6 pT/√Hz achieved

Minimum detectable ECD moment of 0.2 nA·m

Feasibility of detecting cortical magnetic fields

Abstract

We employ a dry-type phantom to evaluate the performance of a diamond quantum magnetometer with a high sensitivity of about $6~\mathrm{pT/\sqrt{Hz}}$ from the viewpoint of practical measurement in biomagnetic sensing. The dry phantom is supposed to represent an equivalent current dipole (ECD) generated by brain activity, emulating an encephalomagnetic field. The spatial resolution of the magnetometer is evaluated to be sufficiently higher than the length of the variation in the encephalomagnetic field distribution. The minimum detectable ECD moment is evaluated to be 0.2 nA m by averaging about 8000 measurements for a standoff distance of 2.4 mm from the ECD. We also discuss the feasibility of detecting an ECD in the measurement of an encephalomagnetic field in humans. We conclude that it is feasible to detect an encephalomagnetic field from a shallow cortex area such as the primary somatosensory cortex.