Abstract

We present on our ongoing development of microfabricated optically-pumped magnetometer (OPM) arrays for magnetic field imaging applications, spanning size scales from tens of microns to kilometres. At the heart of the OPMs are microfabricated rubidium vapor cells, which determine the size of the voxel in which the magnetic field is measured. Near-infrared diode lasers are used to create and monitor a spin polarization of the rubidium atoms, a direct measure of the magnetic field. Several of the applications for these OPMs are in the biomedical field. For non-invasive brain imaging, magnetoencephalography (MEG) can benefit from small non-cryogenic magnetometers, as these “on-scalp” sensors hold the promise for images with higher spatial resolution and higher information densities [1–4]. We have developed OPMs with intrinsic field sensitivities as low as 7 fT/Hz^1/2 and built gradiometers with magnetic sensitivities of 10 fT/Hz^1/2 and a 2 cm baseline [5]. We have assembled arrays of them onto flexible helmets and measured spontaneous brain activity as well as visually, auditory, and somatosensory- evoked signals with amplitudes several times higher than standard MEG instruments and imaged the activity.

© 2019 IEEE