Building a Low-Cost Brain-Computer Interface

ESP32 + EEG Sensors = Under $50 BCI

Brain-Computer Interfaces have traditionally been expensive research tools. In this tutorial, we'll build a functional BCI for under $50 using readily available components.

Components Needed

| Component | Purpose | Cost | |-----------|---------|------| | ESP32 DevKit | Main processor | $8 | | AD8232 ECG/EEG Module | Signal acquisition | $12 | | Dry EEG Electrodes x3 | Brain signal pickup | $15 | | Misc (wires, case) | Assembly | $10 |

Architecture Overview

[Electrodes] → [AD8232 Amplifier] → [ESP32 ADC] → [WiFi] → [Python Analysis]

Signal Processing Pipeline

#include <Arduino.h>
#include <WiFi.h>

const int EEG_PIN = 34;
const int SAMPLE_RATE = 256; // Hz

void setup() {
  analogSetAttenuation(ADC_6db);
  analogReadResolution(12);
  
  // Initialize WiFi for data streaming
  WiFi.begin(SSID, PASSWORD);
}

void loop() {
  int rawSignal = analogRead(EEG_PIN);
  
  // Apply digital filtering
  float filtered = bandpassFilter(rawSignal, 8, 30); // Alpha/Beta bands
  
  // Stream via WebSocket
  sendToServer(filtered);
  
  delayMicroseconds(1000000 / SAMPLE_RATE);
}

Applications

Once built, you can use this BCI for:

• Alpha wave meditation feedback
• Focus/attention monitoring
• Simple motor imagery detection

Full build guide with PCB designs coming soon.