Low-Cost Real-Time EEG Acquisition and Analysis for Alpha and Beta Brainwave Bands Using AD8232 and ESP32

Abstract

Electroencephalography (EEG) is a non-invasive technique which can be used for monitoring brain activity in clinical settings, in research and in the context of brain–computer interfaces. Commercial EEG acquisition systems are generally expensive and therefore not accessible to academic institutions and to people who are engaging in prototype development. The present study describes the design and implementation of a low-cost, real-time system for the acquisition and analysis of EEG signals. The system making use of the AD8232 analog front-end, the ADS1115 16-bit analog-to-digital converter and the ESP32 microcontroller. When operating in I2C mode at a sampling rate of 250 Hz, the system is able to reliably pick up EEG signals that have very low amplitude and lie in the microvolt range. For feature analysis, digital signal processing methods are employed, these including bandpass filtering (0.5–40 Hz), 50 Hz notch filtering, power spectral density (PSD) analysis and the extraction of Alpha and Beta band power.
A graphical user interface (GUI) allows for real-time visualisation, for the detection of artefacts and for the classification of mental states on the basis of the Alpha/Beta power. Experimental validation under various cognitive conditions, such as eye-open, eye-closed, and task-based states, demonstrates stable signal acquisition, effective noise suppression, and distinguishable spectral variations across mental states. The proposed system offers a cost-effective and scalable solution suitable for educational, research, and wearable neurotechnology applications as compared with other readymade EEG cap available in market.