Hackaday Prize Entry: Biopotential Signal Library

With prosthetics, EEG, and all the other builds focused on the body and medicine for this year’s Hackaday Prize, it might be a good idea to take a look at what it takes to measure the tiny electrical signals that come from the human body. Measuring brain waves or heartbeats indoors is hard; AC power frequencies easily couple to the high impedance inputs for these measurements, and the signals themselves are very, very weak. For his entry to The Hackaday Prize, [Paul Stoffregen] is building the tools to make EEG, ECG, and EMG measurements easy with cheap tools.

If the name [Stoffregen] sounds familiar, it’s because he’s the guy behind the Teensy family of microcontroller boards and several dozen extremely popular libraries for everything from displays to real time clocks. The biopotential signal library continues in [Paul]’s tradition of building very cool stuff with just code.

The hardware used in this project is TI’s ADS1294, a 24-bit ADC with either 4 or 8 channels. This chip is marketed as a medical analog front end with a little bit of ECG thrown in for good measure. [Paul] is only using the ADS1294 initially; more analog chips can be added later. It’s a great project in its own right, and when you include the potential applications of this library – everything from prosthetics to body sensors – it makes for an awesome Hackaday Prize entry.

The 2015 Hackaday Prize is sponsored by:

Brains Controlling Labyrinths Without Hands

[Daniel], [Gal] and [Maxim] attended a hackathon last weekend – Brainihack 2015 – that focused on neuroscience-themed builds in a day and a half long build off. The trio are communications systems engineering and computer science students with no background in neuroscience whatsoever. You can’t build an FMRI in a day and a half, so they ended up winning the best project in the open source category with a brain-controlled labyrinth game.

The labyrinth itself is entirely 3D printed and much, much simpler than the usual, ‘wooden maze with holes’ that’s generally associated with labyrinth puzzles. It’s really just a plastic spiral for a ball to follow. There’s a reason for this simplicity. The team is using EEG to detect brain waves and move the labyrinth on the X and Y axes.

The team is using OpenBCI for the interface between their brains and a pair of servos. This is actually an interesting piece of tech; unlike a few toys like the NeuroSky MindWave and the Star Wars Force Trainer, the OpenBCI gives you eight input channels that attach to anywhere on the scalp. The team used these inputs to measure Alpha waves and Steady State Visually Evoked Potential to control the pair of servos on the labyrinth frame.

It’s a great build, a wonderful demonstration of a device that outputs real EEG signals, and the team on a prize. What’s not to like?

Use the Force, Luke…to Turn Off Your TV

Have you ever wanted to turn on or off your TV just by thinking about it? We love this hack mainly because it uses an old Star Wars Force Trainer game. You can still buy them for about $40-$80 USD online. This cool little toy was introduced in 2009 and uses a headset with electrodes, and an electroencephalography (EEG) chip. It transmits the EEG data to control a fan that blows air into a tube to “levitate” a ball, all the while being coached on by the voice of Yoda. (Geesh! Kids these days have the best toys!)

[Tinkernut] started by cracking open the headset, where he found the EEG chip made by a company called NeuroSky (talk about a frightening sounding company name). The PCB designer was kind enough to label the Tx/Rx pins on the board, so hooking it up to an Arduino was a snap. After scavenging an IR LED and receiver from an old VCR, the hardware was just about done. After a bit of coding, you can now control your TV by using the force! (Ok, by ‘force’ I mean brainwaves.)  Video after the break.

Note: [Tinkernut’s] blog page should have more information available soon. In the meantime if you can find his Arduino Brain Library on github.

This isn’t the first EEG to TV interface we’ve featured. Way back in 2010 we featured a project that used an Emotiv EPOC EEG headset to turn on and off a TV. But at $400 for the headset, it was a little too expensive for the average Jedi.

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Your New Winter Hat Should Express Your Brain Waves Like a Neon Sign… Just Saying

We’ve seen a few cool hacks for mainstream commercial EEG headsets, but these are all a tad spendy for leisurely play or experimentation. The illumino project by [io] however, has a relatively short and affordable list of materials for creating your own EEG sensor. It’s even built into a beanie that maps your mental status to a colorful LED pompom! Now that winter is around the corner, this project is perfect for those of us who want to try on the mad scientist’s hat and look awesome while we’re wearing it.

How does all the neuro-magic happen? At the heart of [io’s] EEG project is a retired Thinkgear ASIC PC board by Neurosky. It comes loaded with fancy algorithms which amplify and process the different types of noise coming from the surface of our brain. A few small electrodes made from sheets of copper and placed in contact with the forehead are responsible for picking up this noise. The bridge between the electrodes and the Thinkgear is an arduino running the illumino project code. For [io’s] tutorial, a Tinylilly Arduino is used to mesh with the wearable medium, since all of these parts are concealed in the folded brim of the beanie.


In addition, a neat processing sketch is included which illustrates the alpha, beta, gamma, and other wave types associated with brain activity as a morphing ball of changing size and color. This offers a nice visual sense of what the Neurosky is actually reading.

If all of your hats lack pompoms and you can’t find one out in the ether that comes equipped, fear not… there is even a side tutorial on how to make a proper puff-ball from yarn. Sporting glowing headwear might be a little ostentatious for some of us, but the circuit in this project by itself is a neat point of departure for those who want to poke around at the EEG technology. Details and code can be found on the illumino Instructable.

Thanks Zack, for showing us this neat tutorial!

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An Open Hardware Platform for ECG, EEG and Other Measurements

[Eric] tipped us about the OpenHarwareExG project which goal is to build a device that allows the creation of electrophysiological signal processing applications. By the latter they mean electrocardiography (ECG, activity of the heart), electroencephalography (EEG, signals on the scalp), electromyography (EMG, skeletal muscles activity), electronystagmography and electrooculography (ENG & EOG, eye movements) monitoring projects. As you can guess these signals are particularly hard to measure due to their small amplitude and therefore susceptibility to electrical noise.

The ADS1299 8-channel 24-bit analog front end used in this platform is actually electrically isolated from the rest of the circuit so the USB connection wouldn’t perturb measurements. An Arduino-compatible ATSAM3X microcontroller is used and all the board is “DIY compatible” as all parts can be sourced in small quantities and soldered by hand. Even the case is open source, being laser cut from acrylic.

Head to the project’s website to download all the source files and see a quick video of the system in action.

Interested in measuring the body’s potential? Check out an ECG that’s nice enough to let you know you have died, or this Android based wireless setup.


Electrooculograph (EOG) from a Video Stream


[Michael] from Lucidcode is at it again, this time with an Android app called Halovision.

In case you don’t remember, this is the guy who has been working on the Lucid Scribe Project, with the end goal of communicating from inside your dreams! Here’s the basic gist of it. If we can use a sensor to detect REM (rapid eye movement) or body movement during sleep, we can tell if we’re dreaming — then it’s just a matter of using an audible cue to inform the sleeper of the dream, so they can take control and become lucid.

The first way they did this was by using commercial EEG headsets to detect REM. We covered a hack on modifying one so it would be more comfortable to wear at night, but what is really exciting is [Michael’s] new app, Halovision — No EEG required

It’s an Android app that uses the camera to detect movement during sleep, and it is only the first plugin planned for Lucid Scribe. The algorithm is still in its experimental stages, but it is at least somewhat functional at this time. They note it’ll only work for day-time naps or with a bright night light, but this could be easily solved with an IR webcam and a few IR LEDs.

It will be interesting to see where this all goes, has anyone else been following or participating in Lucid Scribe?

Building a blink based input device


Fans of the AMC show Breaking Bad will remember the Original Gangsta [Hector Salamanca]. When first introduced to the story he communicates by ringing a bell. But after being moved to a nursing home he communicates by spelling out messages with the assistance of a nurse who holds up a card with columns and rows of letters. This hack automates that task, trading the human assistant for a blink-based input system.

[Bob Stone] calls the project BlinkTalk. The user wears a Neurosky Mindwave Mobile headset. This measures brainwaves using EEG. He connects the headset to an mBed microcontroller using a BlueSMiRF Bluetooth board. The microcontroller processes the EEG data to establish when the user blinks their eyes.

The LCD screen first scrolls down each row of the displayed letters and numbers. When the appropriate row is highlighted a blink will start scrolling through the columns until a second blink selects the appropriate character. Once the message has been spelled out the “SAY!” menu item causes the Emic2 module to turn the text into speech.

If you think you could build something like this to help the disabled, you should check out thecontrollerproject.com where builders are connected with people in need.

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