Imec, Holst Centre and Panasonic have unveiled a new version of their wireless EEG headset. The device monitors brain waves using eight channels and transmits readings directly to a wireless receiver up to 10 meters (30 feet) away. Because it can be applied by the user without assistance from a highly trained professional, coupled with the fact that it can be used outside the clinic, the device may open new doors for using EEG to study the brain in a variety of situations and environments.
Advancements in the new system over the previous model include continuous impedance monitoring for signal consistency and confidence in the readings, as well as a see-through design that makes it look like the wearer might be receiving signals from someone in deep space.
More technical details about the system from the press release:
The system integrates circuit level components including imec’s active electrodes and EEG amplifier together with a microcontroller and a low power radio. It is capable of continuously recording 8 channel EEG signals while concurrently recording electrode-tissue contact impedance (ETI). This simultaneous ETI recording enables continuous, remote assessment of electrode contact status during EEG recording. The active electrodes reduce the susceptibility of the system to power-line interference and cable motion artifacts, thus improving signal quality. The system can be configured at run-time to change the settings of the recordings such as the number of channels, or enabling/disabling the impedance recording. The autonomy of the system ranges from 22 hours (8 channels of EEG with ETI) to 70 hours (1 channel of EEG only).
The system has a high common-mode rejection ratio (>92 dB), low noise (<6 µVpp, 0.5-100Hz), DC offset tolerance of +/- 900mV and is AC coupled with configurable cut-off frequency. Sensitivity and dynamic range are configurable through a programmable gain stage (default 1.5mVpp and 366nV, respectively).The system (with dry electrodes and no skin preparation) is validated against a commercially available wired reference system (with wet electrodes and skin preparation), comparing the spectra between 1 and 30Hz. The high correlation coefficients (ranging from 0.81to 0.98 in four 1-minute recordings with eyes open) indicate that both systems have similar performance.
The heart of the system is the low-power (750µW) 8-channel EEG monitoring chipset. Each EEG channel consists of two active electrodes and a low-power analog signal processor. The EEG channels are designed to extract high-quality EEG signals under a large amount of common-mode interference. The active electrode chips have buffer functionality with high input impedance (1.4GΩ at 10Hz), enabling recordings from dry electrodes, and low output impedance reducing the power-line interference without using shielded wires
The system is integrated into imec’s EEG headset with dry electrodes, which enables EEG recordings with minimal set-up time. The small size of the electronics system, measuring only 35mm x 30mm x 5mm (excl battery), allows easy integration in any other product.
(hat tip: Neurogadget.com)