Bio Sensing

HEGduino V2

A flexible FNIRS and blood-flow biofeedback Kit

$11,598 raised

of $7,500 goal

154% Funded!
Not Available
Jun 22 2021
funded on

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MAX86141-Based NIR-HEG

We’ve been working continuously for over a year and a half—since well before the release of HEGduino V1—to develop a compact, state-of-the-art, open hardware solution for home NIR-HEG biofeedback. HEGduino V2 is an original design that brings you low-cost, intuitive home brain training and research-grade cerebral blood-flow monitoring. This new device also lets us incorporate Heart Rate Variability (HRV) training and can even monitor breathing and skin temperature.

HEGduino V2 comes in a comfortable. easy-to-use headset with support for wireless operation and battery power. The components are breakout boards that let you detach them from the headset to tinker with or replace easily.

Technical Specifications


HEGduino V2HEGduino V1MendiPeanut nIRHEG
Cost (USD)$80 $60 $300-$500 $495-$895
Resolution (bits)19 16 (12-15 actual) Not public 21 Bit
Sampling Rate (max)4096x2 SPS 860 SPS (120 sps actual) Not public ~2000 SPS?
Monitor Heart Rate and Breathing?Yes No No No
Monitor Temperature?Yes No No No
SoftwareMobile or Desktop Mobile or Desktop Mobile Desktop
Open Hardware?Yes Yes No No
Open Software?Yes Yes No Obsolete

What Is HEG?

HEG stands for Hemoencephalography, which just means "monitoring blood flow in the brain." It is complementary to Electroencephalography (EEG), which involves monitoring the brain’s electrical signals. HEG—or, more broadly, Functional Near Infrared Spectroscopy (FNIRS)—is increasingly recognized as an essential source of information about brain activity and brain health. For our purposes, it assists with breathing exercises and obtaining essential feedback on how well our brain is circulating blood and energy.

Live brain-pulse data from the HEG. (You can do HRV and HEG training simultaneously!)

HEGduino V2’s easy-to-use software will help you get started with home brain training as quickly as possible, and its uncompromising hackability will allow you to explore the science and engineering readily. And there’s more on the way! We have additional projects in the works for 2021, including the FreeEEG32, which will be launching soon on Crowd Supply, and which will dovetail nicely with the work around HEGduino V2.

We are continuing to develop more affordable hardware so that we can eventually make multi-sensor, multi-modal BCIs feasible for students, out-of-pocket researchers, and anyone else who wants to learn more about their brains and themselves.


We are partnering with the open source (GPLv3) Brains@Play general Brain-Computer Interface (BCI) platform to develop neurofeedback experiences for home use. This platform will allow student developers to get involved with creating their own standalone brain applications or by contributing to our main feature set. We are working to become a hub for lots of exciting, community-driven, brain-controlled content.

Among other features, our new platform supports multiple simultaneous users, remote-streaming, GPU-accelerated real-time signal analysis and visualization, and various types of concurrent hardware streams, including EEG, HEG, and streams from novel devices like Neosensory. We are even testing support for eye and face tracking and, possibly, for some kinds of brain implants! Our framework is opening the door to endless possibilities.

The following alphas are currently available:

Additionally, biofeedback therapists can access HEGduino v2 using the BioEra software.

Original HEG software (left) vs. the new 100% open source Brains@Play platform (right).

Support & Documentation

HEGduino is an open science project dedicated to making brain technology more widely accessible. Schematics, design files, firmware, software, and a whitepaper are all available on our GitHub repository. You can learn more about us on the HEG Alpha webpage. And, if you have a question, please feel free to reach out using the Ask a technical question form on our campaign page. This is an open project, so let’s find ways to work together!

Manufacturing Plan

Our PCBs will be fabricated and assembled by PCBWay, after which they’ll be sent to us for testing and headband assembly. The HEGduino v1 campaign gave us plenty of practice, and we’re excited to continue optimizing and scaling this process. We will ensure that every device works consistently before packaging them up and shipping them to Crowd Supply. That way, you can jump right into training and experimentation rather than spending your time debugging hardware.

Fulfillment & Logistics

We expect to have all HEGduino V2 products manufactured, tested, packaged, and on their way to Crowd Supply’s fulfillment partner within eight weeks of hitting our funding goal. To allow time for shipping logistics (and to give ourselves a bit of a buffer) we’re estimating a ship date of approximately three months after the end of the campaign. Orders will be subject to taxes and shipping fees based on the location of the backer. If you have more questions about shipping, please take a look at the Ordering, paying, and shipping section of the Crowd Supply guide.

Note: The LiPo battery product is only available to US backers. Sorry about that!

Repair Policy

We are continuing our policy of offering free repairs for as long as we have materials available with which to replace broken parts. There may be occasional delays in our supply chain, but we will do our best to ensure that you have a good experience with our products while they continue to improve!

Risks & Challenges

This is a grassroots project. I’ve had many wonderful mentors and contributors—and I’ve even (slowly) managed to assemble a small team—but I built most of HEGduino myself, from scratch, while volunteering the vast majority of my time. At this point, we’re quite familiar with the various pitfalls that surround this area of work, and we know how to avoid them. With your continued support, we’re ready to tackle even bigger problems! Help us get HEGduino V2 out into the world and establish ourselves as a force of nature in the BCI space! We can’t do it without you.

In the Press

CNX Software

"We saw the previous version of the HEGduino in September 2019 which only supported blood flow monitoring. But the HEGduino V2 also monitors breathing, heart rate, and skin temperature."

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Produced by AlasKit in Fairbanks, AK.

Sold and shipped by Crowd Supply.

Mounted FNIRS sensor with headband

Get the new low cost HEG headset with the MAX86141 sensor and ESP32 microcontroller, mounted in a handmade wire and fabric headset. The biofeedback software is free and will be receiving feature support for the foreseeable future. Battery not included.

$80 $8 US Shipping / $18 Worldwide

MAX86141 FNIRS Breakout Board

Get the breakout board for the MAX86141 FNIRS sensor, which doubles as a foldable pulse ox. The sensor requires a SPI interface and 3.3V-5V power from a microcontroller. Comes with male and female pin headers and a free Arduino library.

$35 $8 US Shipping / $18 Worldwide

LiPo Battery

One 1000mAh LiPo battery to be used with your HEG headset. Only available to ship within the USA.

$8 $8 US Shipping / Not Available Outside US

About the Team


Fairbanks, AK  ·

We are a ragtag team of engineers and optimists trying to make a difference in this cold, dark place called Alaska.

Joshua Brewster

See Also

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