Conventional MEG scanners are based on magnetic field detectors that must be cooled to -269 degrees in order to operate. Consequently they are extremely large and cumbersome; the need for thermal insulation means it is hard to get ‘supercooled’ sensors close to the head (reducing sensitivity and spatial accuracy), and because the sensors must be static, the system cannot adapt to different head shapes and sizes and patients must remain still for very long periods. These systems are also extremely expensive. The new system is based upon recently developed “quantum” sensors, which use the fundamental properties of atoms to sense local magnetic fields. These new sensors, called optically-pumped magnetometers or OPMs, do not require cryogenic cooling. They are also extremely small and lightweight (similar in size to a Lego brick). This means they can be mounted in a helmet which the patient wears. The helmet can adapt to any head shape or size, and because it is lightweight and moves with the head, it is completely insensitive to motion. In addition, because no thermally insulating gap between scalp and sensor is required, the sensors get closer to the head and therefore capture a higher amplitude signal, consequently gaining better data.