Active-Electrode Headset Records EEGs Wirelessly

A new prototype of a wireless electroencephalogram (EEG) headset combines ease-of-use with ultralow power electronics.

Developed by Imec (Leuven, Belgium), Holst Center (Eindhoven, The Netherlands), and Panasonic (Osaka, Japan), the system is integrated into an EEG headset with dry active electrodes, which enables EEG recordings with minimal set-up time that are transmitted in real-time to a receiver located up to 10 meters from the system. The system integrates circuit level components, including Imec’s active electrodes and EEG amplifier, together with a microcontroller and a low power radio. The system is capable of continuously recording eight channel EEG signals while concurrently recording electrode-tissue contact impedance (ETI).

The simultaneous ETI recording enables continuous, remote assessment of electrode contact status during EEG recording, reducing the susceptibility of the system to power-line interference and cable motion artifacts, thus improving signal quality. The heart of the system is a low-power (750 µW) eight-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 (1.4 GΩ at 10 Hz), enabling recordings from the dry electrodes, and low output impedance that reduces the power-line interference without having to use shielded wires. 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 (eight channels of EEG with ETI) to 70 hours (one channel of EEG only).

Related Links:
Imec
Holst Center
Panasonic