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Optical Magnetometry

Working group 8.21


Multichannel systems of superconducting quantum interferometers (SQUIDs) are typically used for magnetoencephalography (MEG). Since SQUIDs only work at temperatures close to absolute zero (about -269°C), these systems are large and inflexible. PTB's 128-SQUID system is visible in the background. The future alternative may be optically pumped magnetometers (OPMs). In the foreground: commercial OPMs in a 3D-printed holder. In this way, the sensor arrangement can be adapted to the anatomy of the respective head and the test person is also free to move during the measurement.

Magnetoencephalography (MEG)

MEG is a non-invasive and contact-free method of measurement to investigate the electrical activity of the human brain. In MEG superconducting interference devices (SQUIDs) are used to record the tiny biomagnetic signals that are produced by electrical currents from neuron populations in the brain. The helmet MEG system of PTB comprises 128 SQUID sensors arranged in a spherical geometry in order to catch activity from many patches of the cerebral cortex. The MEG system is employed together with university hospitals and other research institutes for the further development of biomagnetic metrology as well as neurological diagnostics.

MEG with optically pumped magnetometers

Besides SQUIDs, the group increasingly uses optically pumped magnetometers (OPMs) for magnetoencephalography. The main advantage of OPMs is their greater flexibility. The individual sensors have a volume of just a few cubic centimeters and can be combined in almost any arrays. In this way, individualized sensor arrays can be realized that are optimized for the specific measurement task.

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