All About Biosignals

DIY medical science is fun stuff. One can ferret out many of the electrical signals that make the body run with surprisingly accessible components and simple builds. While the medical community predictably dwells on the healthcare uses of such information, the hacker is free to do whatever he or she wants.

A good first start is to look at the relatively strong electrical signals coming off of the heart and other muscles. [Bernd Porr] has put together a simple bioamplifier circuit, and his students have made a series of videos explaining its use that’s well worth your time if you are interested in these things.
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Hacklet 105 – More Mind and Brain Hacks

A mind is a terrible thing to waste – but an awesome thing to hack. We last visited brain hacks back in July of 2015. Things happen fast on Miss a couple of days, and you’ll miss a bunch of great new projects, including some awesome new biotech hacks. This week, we’re checking out some of the best new mind and brain hacks on

We start with [Daniel Felipe Valencia V] and Brainmotic. Brainmotic is [Daniel’s] entry in the 2016 Hackaday Prize. Smart homes and the Internet of Things are huge buzzwords these days. [Daniel’s] project aims to meld this technology with electroencephalogram (EEG). Your mind will be able to control your home. This would be great for anyone, but it’s especially important for the handicapped. Brainmotic’s interface is using the open hardware OpenBCI as the brain interface. [Daniel’s] software and hardware will create a bridge between this interface and the user’s home.


biofeed1Next we have [Angeliki Beyko] with Serial / Wireless Brainwave Biofeedback. EEG used to be very expensive to implement. Things have gotten cheap enough that we now have brain controlled toys on the market. [Angeliki] is hacking these toys into useful biofeedback tools. These tools can be used to visualize, and even control the user’s state of mind. [Angeliki’s] weapon of choice is the MindFlex series of toys. With the help of a PunchThrouch LightBlue Bean she was able to get the EEG headsets talking on Bluetooth. A bit of fancy software on the PC side allows the brainwave signals relieved by the MindFlex to be interpreted as simple graphs. [Angeliki] even went on to create a Mind-Controlled Robotic Xylophone based on this project.

brainhelmetNext is [Stuart Longland] who hopes to protect brains with Improved Helmets. Traumatic Brain Injury (TBI) is in the spotlight of medical technology these days. As bad as it may be, TBI is just one of several types of head and neck injuries one may sustain when in a bicycle or motorcycle accident. Technology exists to reduce injury, and is included with some new helmets. Many of these technologies, such as MIPS, are patented. [Stuart] is working to create a more accurate model of the head within the helmet, and the brain within the skull. From this data he intends to create a license free protection system which can be used with new helmets as well as retrofitted to existing hardware.

mindwaveFinally we have [Tom Meehan], whose entry in the 2016 Hackaday Prize is Train Your Brain with Neurofeedback. [Tom] is hoping to improve quality of life for people suffering from Epilepsy, Autism, ADHD, and other conditions with the use of neurofeedback. Like [Angeliki ] up above, [Tom] is hacking hardware from NeuroSky. In this case it’s the MindWave headset. [Tom’s] current goal is to pull data from the TAGM1 board inside the MindWave. Once he obtains EEG data, a Java application running on the PC side will allow him to display users EEG information. This is a brand new project with updates coming quickly – so it’s definitely one to watch!

If you want more mind hacking goodness, check out our freshly updated brain hacking project list! Did I miss your project? Don’t be shy, just drop me a message on That’s it for this week’s Hacklet, As always, see you next week. Same hack time, same hack channel, bringing you the best of!

EKG Business Card Warms Our Hearts

Giving out a paper business card is so 1960s. Giving out a PCB business card, well that gets you up to the early 2010s. If you really want to stand out these days, give them a fully-functional EKG in a business card. (Note: works best if you’re leading an open-source electrocardiography project.)

Looking through the schematics (PDF), there’s not much to the card. At the center of everything is an ADuC7061, which is an ARM microprocessor equipped with 24-bit ADCs that also has an internal DAC-driven voltage reference connected to one of the user’s thumbs. This, plus a little buffering circuitry, seems to be enough to translate the tiny voltage potential difference across your two hands into a beautiful signal on the included OLED display. Very nice!

Everything (including the big version of their EKG) is open source and made on an open toolchain. If you’re interested in health and medical sensing, you should head over to the project’s GitHub and check it out. The standalone open EKG is based on a much more complicated circuit, and stands to be more accurate. But the business card version is just soooo cute!

Thanks [Ag Primatic] for the tip!

Amplifying the Body’s Own Electricity

Measuring the body’s electrical signals is a neat trick… if you can get your equipment dialed in enough to establish dependable measurements. The technique is called Surface ElectroMyography (SEMG) though you’ll hear many call this ECG. They’re essentially the same technology; the Electro CardioGraph instruments monitor the activity of the heart while SEMG Instruments monitor electrical signals used to control other muscles. Both types of hardware amount to an instrumentation type amplifier and some form of I/O or display.

This topic has been in my back pocket for many months now. Back in May we Hackaday’ites descended on New York City for the Disrupt NY Hackathon event. We arrived a day or so early so that we might better peruse the Korean BBQ joints and check out the other electronics that NY has to offer. On Saturday we gathered around, each shouting out the size of his or her t-shirt preference as we covered up our black Hackaday logo tees with maroon maroon ones (sporting the Hackaday logo of course) for a 24-hour craze of hardware hacking.

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There were two individuals at our tables who were both hacking away on hardware to measure the electrical field produced by the body’s muscles in some form or another. The electrical signals measured from the skin are small, and need careful consideration to measure the signal despite the noise. This is a fun experiment that lets you work with both Instrumentation Amplifiers and OpAmps to achieve a usable signal from the movement of your body.

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Hacklet 56 – Brain Hacks

The brain is the most powerful – and least understood computer known to man. For these very reasons, working with the mind has long been an attraction for hackers, makers, and engineers. Everything from EEG to magnetic stimulus to actual implants have found their way into projects. This week’s Hacklet is about some of the best brain hacks on!

teensy-bio[Paul Stoffregen], father of the Teensy, is hard at work on Biopotential Signal Library, his entry in the 2015 Hackaday Prize. [Paul] isn’t just hacking his own mind, he’s creating a library and reference design using the Teensy 3.1. This library will allow anyone to read electroencephalogram (EEG) signals without having to worry about line noise filtering, signal processing, and all the other details that make recording EEG signals hard. [Paul] is making this happen by having the Teensy’s cortex M4 processor perform interrupt driven acquisition and filtering in the background. This leaves the user’s Arduino sketch free to actually work with the data, rather than acquiring it. The initial hardware design will collect data from TI ADS129x chips, which are 24 bit ADCs with 4 or 8 simultaneous channels. [Paul] plans to add more chips to the library in the future.


bioxNext up is [Jae Choi] with Lucid Dream Communication Link. [Jae] hopes to create a link between the dream world and the real world. To do this, they are utilizing BioEXG, a device [Jae] designed to collect several types of biological signals. Data enters the system through several active probes. These probes use common pogo pins to make contact with the wearer’s skin. [Jae] says the active probes were able to read EEG signals even through their thick hair! Communication between dreams and the real world will be accomplished with eye movements. We haven’t heard from [Jae] in awhile – so we hope they aren’t caught in limbo!

bioloop[Qquuiinn] is working from a different angle to build bioloop, their entry in the 2015 Hackaday Prize. Rather than using EEG signals, [Qquuiinn] is going with Galvanic Skin Response (GSR). GSR is easy to measure compared to EEG signals. [Qquuiinn] is using an Arduino Pro Mini to perform all their signal acquisition and processing. This biofeedback signal has been used for decades by devices like polygraph “lie detector” machines. GSR values change as the sweat glands become active. It provides a window into a person’s psychological or physiological stress levels. [Qquuiinn] hopes bioloop will be useful both to individuals and to mental health professionals.

biomonitorFinally we have [Marcin Byczuk] with Biomonitor. Biomonitor can read both EEG and electrocardiogram (EKG) signals. Unlike the other projects on today’s Hacklet, Biomonitor is wireless. It uses a Bluetooth radio to transmit data to a nearby PC or smartphone. The main processor in Biomonitor is an 8 bit ATmega8L. Since the 8L isn’t up to a lot of signal processing, [Marcin] does much of his filtering the old fashioned way – in hardware. Carefully designed op-amp based active filters provide more than enough performance when measuring these types of signals. Biomonitor has already found it’s way into academia, being used in both the PalCom project, and brain-computer interface research.

If you want more brain hacking goodness, check out our brain hacking project list! Did I miss your project? Don’t be shy, just drop me a message on That’s it for this week’s Hacklet, As always, see you next week. Same hack time, same hack channel, bringing you the best of!

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:

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.