Kernel Flux: a whole-head 432-magnetometer optically-pumped magnetoencephalography (OP-MEG) system for brain activity imaging during natural human experiences

MEG based on optically-pumped magnetometry (OP-MEG) operates with miniaturized, wearable insulation, in contrast to massive cryogenic dewars for SQUID-MEG, and allows placement of the sensors close to the scalp. This allows more natural head motion during data recording and localized signal quality comparable to, or surpassing, SQUID-MEG. However no OP-MEG system to date has offered full-head coverage with dense sensor packing, and existing systems - as with SQUID-MEG - require the subject to be sealed in a multilayer, passively-shielded vault in order to suppress ambient magnetic fields. Here we present Kernel Flux, which overcomes these limitations. Kernel Flux uses a collection of alkali vapor sensors in a unique array architecture to directly detect the magnetic fields generated by collective neural activity in the brain, while allowing for comfortable head motion. Each Kernel Flux OP-MEG system was designed from the ground up to work as an integrated system optimized around the user's experience, with relevance to natural home and office contexts.