Noninvasive EEGs

Conventional electroencephalograms (EEGs) monitor electrical activity in the brain with electrodes placed either on the scalp (involving hair removal and skin abrasion) or inserted directly into the brain with needles.

Now a noninvasive form of EEG has been devised by scientists at the University of Sussex. Instead of measuring charge flow through an electrode (with attendant distortions, in the case of scalp electrodes) the new system measures electric fields remotely, an advance made possible by new developments in sensor technology.

The device's sensitivity is demonstrated by watching electric activity change as the ambient relaxed brain signal (the so-called alpha wave, at a frequency of 8-14 Hz) gives way to the beta wave (14-35 Hz) as the subject opens his eyes (see figure).

The Sussex researchers (contact Terry Clark, t.d.clark@sussex.ac.uk, 44-127-678087) believe their new sensor will instigate major advances in the collection and display of electrical information from the brain, especially in the study of drowsiness and the human-machine interface. The same group of scientists has made remote-sensing ECG units as well. (Harland et al., Applied Physics Letters, 21 October 2002; see research website.)