Optically pumped magnetometers for wearable magnetoencephalography

Short answer: Magnetoencephalography (MEG) measures the magnetic fields produced by electrical activity in neurons. A 2018 Nature paper described a MEG system worn like a helmet that uses optically pumped magnetometers (OPMs) instead of superconducting sensors, and a 2022 review in Trends in Neurosciences summarises the approach. The claims below are the authors' own research-stage findings.

What problem does OPM-MEG address?

The 2018 Nature abstract says imaging human brain function with MEG typically requires a subject to perform tasks while their head stays still within a restrictive scanner. The authors say this artificial environment makes the technique inaccessible to many people and limits the questions that can be asked. They give two examples: applying neuroimaging to the neural basis of cognitive development in babies and children, and studying processes in adults that need unconstrained head movement, such as spatial navigation.

The 2022 review makes the same point in its highlights. Current MEG technology, it says, has significant limitations, with cumbersome field sensing technologies creating major barriers to use.

What did the 2018 system do?

The authors describe a MEG system that can be worn like a helmet, allowing free and natural movement during scanning. They attribute this to the integration of quantum sensors, which do not rely on superconducting technology, with a system for nulling background magnetic fields. They demonstrate human electrophysiological measurement at millisecond resolution while subjects make natural movements, including head nodding, stretching, drinking and playing a ball game. They write that their results compare well with the current state of the art, even when subjects make large head movements. They name possible applications such as characterising the neurodevelopmental connectome, imaging subjects moving naturally in a virtual environment, and investigating the pathophysiology of movement disorders. These are listed as possibilities.

The paper's competing-interest statement, as shown on the article page, says one author is the founding director of a company that sells OPM magnetometers and that the company built the sensors used and advised on the system design, but played no part in the subsequent measurements or data analysis. This post does not evaluate any commercial product.

What does the 2022 review say?

The review, titled "Magnetoencephalography with optically pumped magnetometers (OPM-MEG): the next generation of functional neuroimaging", lists several advantages that OPM-MEG is described as promising compared with conventional scanners: higher signal sensitivity, better spatial resolution, more uniform coverage, lifespan compliance, free movement of participants during scanning, and lower system complexity. The word "promising" is the authors', and the highlights give no numbers. The review says it describes the principles of OPM-MEG and its components, including noncryogenic field sensors and magnetic shielding technologies, and discusses how the technology is affecting neuroscience.

How does this connect to atomic magnetometers?

The sensors are a form of quantum magnetometer: they read out the spin of atoms in a vapour using light. The page text read for this post describes the sensors only as quantum sensors, and does not give their specifications.

How to read this

This post is based on one primary paper and one review, using abstracts, highlights and visible page text. Full texts were not checked, and the 2018 result is a research demonstration and not a clinical study. It makes no claim about hospital use.

FAQ

What is OPM-MEG?

MEG that uses optically pumped magnetometers, which are quantum sensors that do not need superconducting technology, per the 2018 paper.

Why does head movement matter?

Conventional scanners need the head to stay still, which limits who can be scanned and which tasks can be studied, according to the 2018 abstract.

What advantages does the review list?

Higher sensitivity, better spatial resolution, uniform coverage, lifespan compliance, free movement and lower system complexity, described as promised advantages.

Is it in routine clinical use?

Neither source says so. Both describe research applications.