HEGduino V2

A Flexible FNIRS and Blood-flow Biofeedback Kit

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The HEGduino V2 is the follow-up to the successful HEGduino V1. The HEGduino V2 provides the kind of state-of-the-art signal quality you should expect from new hardware, and improves on the software platform for affordable, adaptive, and open source BCI.

Dual Functionality and Versatility

The HEGduino V2 device doubles as a pulse oximeter and an FNIRS/HEG device. The tiny flexible board form factor may be used either in a headset or in foldable pulse oximeters. You can get the breakout boards standalone for your DIY projects.

Our assembled kit comes with our flexible MAX86141 breakout board mounted on a simple headset with an ESP32 board with battery support, to allow the device to be worn wirelessly and with a more low profile design than the V1 HEGduino. It can be fully disassembled for repurposing or repair, too.

API and Web Support

The HEGduino V2 comes with a free, easy to use mobile or desktop biofeedback webapp, with API support that has been evolving all 2020 since the initial HEGduino release, and will continue being innovated on. You can demo it now already at https://hegalomania.netlify.app, expect drastic improvements as we continue development, including a total redesign being released within the next couple months to mesh with the FreeEEG32 software we’ve developed to support the upcoming release.

What’s Included?

The HEGduino V2 comes fully assembled and ready to use with the custom, flexible MAX86141 sensor and an ESP32 with wireless Wi-Fi or BT communication and battery support. The sensor and microcontroller are attached together on a flex piece which attaches to the headset. They are placed on stacking headers so the devices can be disassembled and repurposed or cheaply repaired. Otherwise, the standalone breakout boards come with headers ready to be soldered.

What’s different from the HEGduino V1?

  • Significantly improved signal quality, allows for clinical grade data
  • Higher caliber hardware enables much deeper insight possibilities (e.g. seeing brain waves in cerebral fluid, brain blood pressure monitoring, Heart/Pulse Rate Variability)
  • Lower profile design.
  • Expanded software support to mesh with our upcoming EEG software (will still support V1)


  • Sensor: MAX86141 pulse oximeter ADC
    • 2x4096 sps simultaneous sensing with 2 high sensitivity BPW34S photodiodes
    • 19 bits resolution
    • Hardware ambient cancellation and error detection
    • Fully customizable LED routines, power usage, sampling rates, etc.
    • Hardware & Software IIR filters for AC power and high frequency noise ensures a high quality signal.
    • Final design will have 2 IR LEDs and 1 Red LED for HEG/FNIRS and oximetry.
  • Microcontroller: ESP32 breakout board
    • 32bit, 4MB, 240MHz dual-core ESP32 microcontroller with rechargeable battery support
    • Wi-Fi, BT/BLE, and USB connectivity
    • Fully customizable firmware via Arduino and Espressif IDEs
    • Free IoT software and tools to use your HEG on any device with no installs necessary

Use cases:

  • HEG Brain Blood Flow Biofeedback!
  • Simplified FNIRS data acquisition
  • Pulse Oximetry (Heart Rate and SpO2)
  • Heart Rate Variability (HRV)
  • Head mounted display biometrics (e.g. in VR headsets)

Open Source Information

Schematics, designs, firmware, software, and a new whitepaper are all available on GitHub.

Visit our home page HEG Alpha

This is an open science project dedicated to making brain technology more widely accessible.

See Also

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