Physicians monitor the brain’s electrical signals via an EEG and specialized electrodes implanted into, or placed on, the surface of the head. Scientists can incorporate EEGs into “brain-machine interfaces,” that use brain waves to control an external device. For non-invasive versions, the “wet” sensors are stuck onto the head with a gloopy gel that can irritate the scalp and sometimes trigger allergic reactions.
The researchers wanted to create a 3D, graphene-based sensor based on polycrystalline graphene that could accurately monitor brain activity without any stickiness. Of the shapes tested, a hexagonal pattern worked the best on the curvy, hairy surface of the occipital region at the base of the head, where the brain’s visual cortex is located. The team incorporated eight of these sensors into an elastic headband, which held them against the back of the head.
When used with an augmented reality headset, the electrodes could detect which cue was being viewed, then work with a computer to interpret the signals into commands that controlled the motion of a four-legged robot, hands-free. The work represents a first step toward developing robust, easily implemented dry sensors to help expand the applications of brain-machine interfaces.
