Imec, Holst Centre, and Panasonic develop brainwave headset

Imec, Holst Centre, and Panasonic have developed a new prototype wireless EEG (electroencephalogram) headset. The system combines ease-of-use with ultra-low power electronics. Continuous impedance monitoring and the use of active electrodes increases the quality of EEG signal recording compared to former system versions. Data is transmitted in real-time to a receiver located up to 10 m from the system. The realization of this prototype is a next step towards reliable high-quality wearable EEG monitoring systems. 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 ETI (electrode-tissue contact impedance). 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 CMRR (> 92 dB), low noise (<6 μ V pp, 0.5 - 100 Hz), DC offset tolerance of ±900 mV and is AC coupled with configurable cut-off frequency. Sensitivity and dynamic range are configurable through a programmable gain stage (default 1.5 mV pp and 366 nV, 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 30 Hz. The high correlation coefficients (ranging from 0.81 to 0.98 in four one-minute recordings with eyes open) indicate that both systems have similar performance. The heart of the system is the low-power (750 μW) 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 (1.4 G? at 10 Hz), 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 35 x 30 x 5 mm (excluding battery), allows easy integration in any other product. Imec Holst Centre