Research-Grade EEG Equipment That Won’t Break the Bank

FreeEEG32 is a stackable, open source, 32-channel, 24-bit, sigma-delta, simultaneous-sampling board meant to satisfy the needs of scientists and brain hackers who need high-quality, affordable, research-grade equipment. We have been developing this EEG for several years now, as we work to create the definitive open source answer to expensive, proprietary EEG technology.

FreeEEG32 combines four 8-channel AD7771 ADCs with ultra-low-noise (<0.22 μV measured) sources and references, all driven by a powerful STM32H7 ARM Cortex-M7 that also handles pre-processing. It is sensitive enough to handle high-quality EEG data acquisition and much, much more.

FreeEEG32 is available under the Affero-General Public License (AGPL). Project files are available in our GitHub repository.

Features & Specifications

• Four AD7771 Analog-to-Digital Converters
  • 24-bit, up to 128 kSPS simultaneous sampling ¹
  • Eight channels per ADC
  • Up to 8x programmable gain amplification
  • 107 dB dynamic range at 32 kSPS
  • Onboard SAR (Successive-Approximation-Register) ADC for diagnostics
• STM32H7 ARM Cortex M-7 Microcontroller
  • 480 MHz CPU
  • 1027 DMIPS (Dhrystone Million Instructions Per Second)
  • 2 MB flash, 1 MB SRAM, 16 kB L1-cache
  • Double-precision floating point unit (FPU) for deep learning, etc.
  • Chrom-ART graphics acceleration
  • Dozens of communication protocols
• Separate USB ports isolate power and logic to meet safety standards
• SD card slot for data collection or to extended program storage
• Stacking headers with possible I²C integration for stacked output through one board
• Available with loose or pre-soldered headers (not compatible with our custom headsets)
• (WIP) Possible accelerometer support for basic movement tracking when head-mounted

¹ To meet EEG standards, FreeEEG32’s firmware is optimized for 512 SPS per channel when running all 32 channels simultaneously

The boards also come with an STM32 blue pill for programming and experimentation.

Stackable Up to 256 Channels

By stacking FreeEEG32 boards, you can achieve simultaneous streaming for 64-256 channels, or more, which makes FreeEEG32 the most affordable high-density EEG system on the market. Each board connects independently to the host computer but can stream to the same software instance for mass data collection.

Custom Headsets

Bernard Markus, a long-time traveling Transcendental Meditation teacher from the Netherlands, has spent the past two years developing his own EEG headset solution using a mix of professionally 3D-printed parts, custom flex PCBs, and hand-crafted, gold-plated wire. These headsets are fully compatible with the EDFbrowser plugin and the Brains@Play platform, which includes supports for all relevant channel configurations. And that’s just the beginning! The list of compatible hardware and software will only grow as support for these headsets spreads within the EEG-research community.

We have two original designs on offer, both of which are dedicated, wearable solutions for FreeEEG32. The first is a 2-channel model with dry electrodes, and the second is a 19-channel model with a saline-sponge net. Each of these comfortable headsets comes in a kit with everything you might need, including a FreeEEG32 board with special headers, a programmer, a case, replacement electrodes or sponges, and various other accessories. These ready-to-use headset kits are the easiest, most effective way to get started with FreeEEG32 and the best way to support our ongoing development in this field. Bernard is planning to assemble these headsets at a German monastery where he and others will be using EEG to study the effects of solo and group meditation, so you will be supporting their efforts as well!

2-Channel Custom Headset

19-Channel Custom headset

Comparisons

Software & Community

We are part of a growing community of developers who are already using our platform and demonstrating its viability. This includes growing software support for various platforms such as Brains@Play (formerly WebBCI), OpenVibe, EDFbrowser, and Brainflow. Come help us chart the future of open-source EEG and biofeedback applications!

Your support will also help us achieve our future hardware and software development goals, including a sub-$100 board with fewer channels, multimodal support, a 64-channel Linux board, and free software optimized for easy home neurofeedback. Future iterations will continue to improve the accessibility of these important technologies!

Open-Source Brain Science

Our goal is to accelerate scientific progress and contribute to medical advances by getting these important technologies into the hands of the students, researchers, and clients who need them. Together, we can participate in one of the most important scientific projects of our era: "solving" the brain. To do that, however, we must reduce both development costs and end-user pricing without sacrificing quality.

FreeEEG32 is part of an ongoing scientific project to probe working memory in the brain and to measure theta and gamma correlations with memory encoding. It is also at the heart of studies that are exploring the effects of group Transcendental Meditation. This project is dedicated to science, to discovery, and to anyone who is working toward those ends. In the interest of improving global scientific discourse and building communities around neurotechnology, this project is entirely open source.

General Purpose Signal Acquisition, Beyond EEG

This board is highly optimized for EEG-related applications, which means that we’ve taken all possible steps to control noise and to isolate power for safe operation. That said, FreeEEG32 also works as a general-purpose signal-acquisition device. If your signal-analysis needs demand 32-channels of simultaneous, 24-bit sampling, then FreeEEG32 has what you need. Examples might include:

• Non-EEG bio-signal acquisition and imaging: ECG, EKG, EMG, FNIRS, etc.
• Creating other types of high-channel signal analysis devices
• Environmental sensing for industrial process control and other applications
• ELF and ULF radio-signal acquisition
• Smart home monitoring and control
• Environmental power- and noise-detection

Support & Documentation

You can visit our GitHub repo for documentation and firmware or join our Discord server if you’d like to get in touch. You can also reach out using the Ask a technical question link on our campaign page.

Manufacturing Plan

This is a global collaboration between like-minded individuals with a shared vision. Our hardware designer, Dmitry, is in Moscow; FreeEEG32 production will be managed out of Oregon, by Josh from the HEGduino project; and headsets will be manufactured in the Netherlands by Bernard. To ensure high quality while keeping costs down, we are partnering with PCBWay in China for FreeEEG32 PCB assembly.

Fulfillment & Logistics

After testing and packaging the production batch of FreeEEG32 products, we will send them on to Crowd Supply’s fulfillment partner, Mouser Electronics, who will distribute them to backers worldwide. You can learn more about Crowd Supply’s fulfillment service under Ordering, Paying, and Shipping in their guide.

Risks & Challenges

Like everyone else these days, we’re up against component shortages that could end up delaying production while we wait for suppliers to replenish their stock. At the moment, the AD7771 analog-to-digital converter, by Analog Devices, is the most likely culprit. We’ll be ready to go when parts become available, however, and we’ll keep you informed through regular campaign updates while we wait.

At the end of the day, this project is a group effort made up of individuals from all over the world. Using our limited, personal resources, we found a way to collaborate, and we leaned on that collaboration to design and build these products from the ground up. Then we worked out how we’re going to make yours and how we’re going to get them into your hands (or onto your head) where they belong. Those were our biggest challenges. At this stage, we’re confident that our collective experience is we need to accomplish the task at hand—our collective experience and your support.