EEG Technology

Overview

Electroencephalography (EEG) is a critical tool in neuroscience, reflecting the summed excitatory and inhibitory postsynaptic potentials of large neuronal populations. Surface electrodes placed on the forehead detect cortical potential differences, which are amplified, filtered, digitized, and analyzed through advanced algorithms. The resulting EEG signals are used to compute parameters such as power spectral density and frequency band ratios. These data support high-resolution waveform and parameter visualization, enabling precise evaluation of brain activity—crucial for applications in neurological assessment and consciousness monitoring.

EEG Measurement PrincipleEEG signals are low-amplitude bioelectrical signals (typically 5–200 µV) with a frequency range of 0.5–30 Hz, making them significantly weaker and more susceptible to interference than ECG signals. As non-stationary, random signals, EEGs are categorized into frequency bands—δ, θ, α, and β waves—each associated with different brain states.Accurate acquisition of high-quality EEG signals is essential for reliable anesthesia depth monitoring. The system architecture includes integrated sensors, shielded cables, precision analog front-end hardware, and digital signal processing within the monitoring platform to ensure signal fidelity and clinical applicability.

Advantages

• High-Performance EEG Signal Extraction

The EEG acquisition system is engineered for optimal signal quality, featuring:

• High common-mode rejection ratio (>120 dB)• High input impedance• Ultra-low system noise (<5 µV)The design integrates multiple critical components, including sensor electrodes, pre-protection and defibrillation circuits, differential pre-amplifiers, myoelectric filtering, baseline rapid recovery, post-amplifiers, precision AD conversion, and impedance detection. This comprehensive architecture ensures stable, accurate, and low-noise EEG signal extraction essential for clinical applications.

• Multifunctional EEG Parameter Calculation

EEG measurement technology supports advanced parameter analysis through a dual-stage algorithm process:

• Signal Preprocessing:High-pass, low-pass, and 50 Hz notch filters are applied to denoise signals. Signal quality and noise levels are assessed to ensure reliability.

• Feature Extraction:◦ Frequency-domain analysis calculates power ratios of α, β, γ, and δ bands.◦ Computes β-ratio, SEF (Spectral Edge Frequency), EMG power, and TP (Total Power).◦ Time-domain analysis derives the Burst Suppression Index (BSI), reflecting cortical inhibition levels.

This comprehensive calculation framework enables accurate assessment of brain activity and anesthesia depth.

• Comprehensive Sensor Compatibility

The EEG measurement system supports multiple sensor configurations, including forehead electrodes, head-mounted electrodes, and EEG caps, enabling flexible adaptation to various clinical and research applications.