Measuring Brain-Signals with neither goo nor shampoo – Fraunhofer scientists present first dry EEG on NIPS

It is based on six distributed contact electrodes that measure brain signals on the scalp. The voltage produced is strong enough to reliably extract EEG potentials in the microvolt range.

Before measuring can be undertaken, ordinary EEG devices have to be mounted on the patients head in a lengthy, time-consuming process. The single electrodes have to be filled with electrolyte gel to achieve electrical contact with the scalp. Setting up such a device takes about 30 minutes. Fraunhofer Scientists now present an alternative that shortens the process to about two minutes.

For this purpose, the scientists constructed a flexible helmet with six electrode arrays (multiple pins arranged in electrode sockets) as well as one reference electrode. The prototype will be used mainly for research purposes – especially in the field of Brain-Computer Interfaces (BCIs). In BCIs, brain signals are measured by means of an EEG, then classified and converted into control signals for the computer. Test persons can think about moving their right or left hand and then cause a cursor on a computer screen to be moved, just by using their imagination. At the NIPS, Fraunhofer researchers demonstrate for the first time how a BCI can be used with a dry electrode cap. A volunteer test person controls a computer game by means of his brain signals.

Preceding the presentation the scientists conducted a study with five healthy test persons. It was published in the scientific journal PLoS ONE. The study aimed at comparing the performance of a standard 64-electrode EEG with the new dry cap. The prototype was an average of 30% slower than the standard device (9,6 vs 14,9 bits/m), but performed just as well as the standard gel-based cap in terms of of maximum transmission rate (36,5 rsp.35,4 bits/m) and reliability (94, 5 rsp. 98% correctly analysed signals). This opens up new perspectives, especially for research in Brain-Computer Interfaces and the use of BCIs for severely disabled patients.

Approximately 1.3 million Euros in funding is being provided for the development of the dry cap under the EU's 6th Framework Programme for Research and Technological Development in connection with the Brain2Robot project.

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