Recently, technological advances in recording EEG from the ear using electrodes placed on the surface of standard earphones have provided a solution—no gel needed. It is not easy though—EEG is very “noisy” since the brain is always actively processing different information. But advanced signal-processing approaches have recently been able to reduce the noisy components, albeit this typically requires powerful computing. This is, however, becoming less of a problem now that mobile-phone processing power is growing rapidly—it should in theory be possible to perform all the required processing on a smart phone.

So why aren’t brainprints everywhere already? One downside is that it can’t be used by twins—they have near-identical EEG patterns. But the main problem is the lack of stability of brainprints over time.

It seems that it is not enough to just have an EEG done once—occasional re-enrolment (say, monthly) is necessary. This is because the brain connections exhibit plastic behavior (they change with experience) and thought processes in the brain change over time. However, in ongoing work at the University of Kent, we have shown that specific tones (which can be played using earphones) can be used to minimize these changes. It is not yet clear exactly how these tones affect the brain but we speculate that they may allow the brain to calm down, allowing more focused activity.