Arduino Powered ECG Informs Users of Their Death

Just when you thought you’d seen an Arduino do everything, [birdyberth] built an Arduino powered Electrocardiogram (ECG or EKG). Electrocardiography is a non invasive method of studying the heart. For many of us that means a 10 minute test during our yearly physical exam. Medical grade ECGs can use up to 10 electrodes. To keep things simple [birdyberth] went the route of a few circuits we’ve seen before, and reduced it to two electrodes and a ground reference. [birdyberth] makes note that the circuit is only safe if battery power is used.

The “heart” of any ECG is an instrumentation amplifier. Instrumentation amplifiers can be thought of as super differential amplifiers. They have buffered inputs, low DC offset, low drift, low noise, high open loop gain, and high impedance among other favorable characteristics. The downside is cost. A typical op amp might cost 0.50 USD in single piece quantities. Instrumentation amplifiers, like [birdyberth’s] INA128 can cost $8.30 or (much) more each. The extra cost is understandable when one thinks about the signals being measured. The ECG is “picking up” the heart’s electrical signals from the outside on skin. On commonly used ECG graph paper, a 1mm square translates to about .1 mV. High gain and clean signals are really needed to get any meaningful data here.

Electrodes are another important part of an ECG. Medical grade ECG units typically use disposable adhesive electrodes that make a strong electrical connection to the skin, and hurt like heck when they’re ripped off by the nurse. [birdyberth] was able to make electrodes using nothing more than tin foil and paper clips. We think the real trick is in the shower gel he used to make an electrical connection to his skin. While messy, the gel provides a low resistance path for the tiny currents to flow.

The actual processing in [birdyberth’s] circuit is easy to follow. The signal from the instrumentation amplifier is sent through a low pass filter, through a 741 op amp, and then on to the Arduino. The Arduino uses a 16×2 LCD to display heart rate in beats per minute, along with a friendly message informing you if you are alive or dead. The circuit even provides audible feedback for heart beats, and the classic “flatline tone” when the users either disconnects the electrodes or expires. [birdyberth] has also plugged in his pocket oscilloscope just after the low pass filter. As his video shows, the familiar ECG waveform is clearly visible. We’d love to see a more complex version of this hack combined with [Addie’s] heart simulator, so we could know exactly which heart malady is killing us in real time!

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Wearing a Homemade EKG Whilst Base Jumping!


[Andrew Wilson] is a pretty extreme guy. He base jumps for fun, and is also a hacker. And while you can try to explain the awesome adrenaline rush that comes with this kind of extreme hobby, it’d be nice if you could show it off, you know, quantitatively. So, he decided to make his own EKG, pair it with his GoPro, and go for a jump!

An EKG is an electrocardiogram — a fancy term for a heart rate monitor — and [Andrew’s] has built his own using a small instrument amplifier circuit. This circuit amplifies the differential signal put out by your heart. The data are fed through an ADC on an Arduino Uno, and then saved to a SD card. He also added a piezo buzzer to try to help sync the data to the video — unfortunately it was too quiet for the GoPro to pick up. So for now he’s stuck with pressing record and start on his EKG at the same time.

Once he was satisfied with a few safe tests, he decided to take it for a base jump. For our viewing pleasure, he’s taken the data collected from the EKG and post-processed it into a nice scrolling graph overlay for the video.

We guarantee your hands will get sweaty as his heart rate goes up as he prepares to make the plunge.

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Immersion: Video Game Biofeedback


We’re not sure how scientific the following hack is, but it’s certainly interesting. Designer [Samuel Matson], interested in the correlation between gaming and stress, has pieced together a device that provides biofeedback during gameplay. He referenced this /r/gaming thread—which measured a player’s heart rate during a Halo session—as well as conducted his own tests that monitored the heart rate of gamers. After several iterations, [Samuel] had the above-pictured headset, which features the familiar and hackable pulse sensor placed by the earpiece.

The headset uses a TinyDuino and a Bluetooth TinyShield to communicate to the gamer’s computer in real time. He didn’t stop with simply monitoring heart rates, however; he integrated the signal into the game design. [Samuel] used indie-favorite game engine Unity3d to create a third-person shooter that reacts to the pulse sensor by raising the difficulty level when the player’s heart rate increases. It seems that his goal is to reduce or control stress among players, but we suspect inverting the model may be more effective: have the game cut you some slack when you’re stressed and present a challenge when you’re mellow.

[Thanks Ken]

The Berkeley Tricorder is now Open Source!

[Reza Naima] has just released the designs for his Berkeley Tricorder for the public to use. He’s been designing it since 2007 as his thesis work for his PhD, and since he’s done now (Congrats!), he decided to let it grow by making it open source!

We covered it almost 7 years ago now when it was in its first prototype form, and it has come a long way since then. The latest version features an electromyogram (EMG), an electrocardiograph (ECG), a bioimpedance spectrometer, a pulse oximeter, an accelerometer, and all the data is recorded to a micro SD card or sent via bluetooth to a tablet or smart phone for data visualization.

He’s released it in hopes that other researchers can utilize the hardware in their own research, hopefully springing up a community of people interested in non-invasive health monitoring. With any luck, the development of the Berkeley Tricorder will continue, and maybe some day, can truly live up to its name!

Unfortunately there’s no new video showing off the latest iteration, but we’ve attached the original video after the break, which gives a good narrative on the device by [Reza] himself.

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PhotoTransistor Based Eye-Tracking


The applications of eye-tracking devices are endless, which is why we always get excited to see new techniques in measuring the absolute position of the human eye. Cornell students [Michael and John] took on an interesting approach for their final project and designed a phototransistor based eye-tracking system.

We can definitely see the potential of this project, but for their first prototype, the system relies on both eye-tracking and head movement to fully control a mouse pointer. An end-product design was in mind, so the system consists of both a pair of custom 3D printed glasses and a wireless receiver; thus avoiding the need to be tethered to the computer under control . The horizontal position of the mouse pointer is controlled via the infrared eye tracking mechanism, consisting of an Infrared LED positioned above the eye and two phototransistors located on each side of the eye. The measured analog data from the phototransistors determine the eye’s horizontal position. The vertical movement of the mouse pointer is controlled with the help of a 3-axis gyroscope mounted to the glasses. The effectiveness of a simple infrared LED/phototransistor to detect eye movement is impressive, because similar projects we’ve seen have been camera based. We understand how final project deadlines can be, so we hope [Michael and John] continue past the deadline with this one. It would be great to see if the absolute position (horizontal and vertical) of the eye can be tracked entirely with the phototransistor technique.

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Acoustic Wayfinder for the Visually Impaired

Ideally, technology is supposed to enhance our lives. [Shane and Eileen], two seniors at Cornell have found a great way to enhance the lives of visually impaired individuals with their acoustic wayfinding device. In brainstorming for their final project, [Shane and Eileen] were inspired by this Hackaday post about robots as viable replacements for guide dogs. They sought to provide wearable, hands-free guidance and detection of (primarily) indoor obstacles—namely chairs, benches, and other inanimate objects below eye level.

The wayfinder comprises two systems working in tandem: a head-mounted navigation unit and a tactile sensor worn on the user’s finger. Both systems use Maxbotix LV-MaxSonar-EZ0 ultrasonic rangefinder modules to detect obstacles and vibrating mini-disc motors to provide haptic feedback at speeds proportionate to the user’s distance from an obstacle.

The head unit uses two rangefinders and two vibrating motors. Together, the rangefinders have a field of view of about 120 degrees and are capable of detecting obstacles up to 6.45 meters away. The tactile sensor comprises one rangefinder and motor and is used in a manner similar to a Hoover cane. The user sweeps their hand to detect objects that would likely be out of the range of the head unit. Both parts are ergonomic and  size-adjustable.

At power up, [Shane and Eileen]’s software performs a calibration of the tactile sensor to determine the distance threshold in conjunction with the user’s height. They’ve used an ATMega 1284 to drive the system, and handled real-time task scheduling between the two subsystems with the TinyRealTime kernel. A full demonstration video is embedded after the break.

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Machine Learning Used to Create an HIV Vaccine


When we think of machine learning it’s usually in the context of robotics—giving an algorithm a large set of input data in order to train it for a certain task like navigation or understanding your handwriting. But it turns out you can also train a nasty virus to go to sleep and never wake up again. That’s exactly what the Immunity Project has been doing. They believe that they have a viable HIV vaccine and are trying to raise about $25 million to begin human testing.

The vaccine hacks the Human Immunodeficiency Virus itself, forcing it to mutate into a dormant form that will not attack its human carrier. It sounds so simple, but a lot of existing knowledge and procedures, as well as new technology, went into getting this far. Last week we spoke with [Reid Rubsamen, M.D.] about the process, which began by collecting blood samples from a wide range of “Controllers“. Controllers are people who carry HIV but manage to suppress the virus’s progression to AIDS. How do you find these people? That’s another story which Scientific American covered (PDF); the short answer is that thanks to the work of [Bruce D. Walker, M.D.] there was already a database of Controllers available.

The information accumulated by [Walker] then underwent a data crunching exercise. The data set was so enormous that a novel approach was adopted. For the laymen this is described as a spam filter: using computers to look at large sets of email to develop a complex process for sifting real messages out of the noise. The task at hand is to look at the genotype of a Controller and compare it with the epitope— a short chain of proteins—in the virus they carry. The power of machine learning managed to whittle down all the data to a list of the  first six epitopes that have the desired dormant-mutation property. The vaccine consists of a cocktail of these epitopes. It does, however, require some clever delivery tactics to reach the parts of the world where it’s most needed. The vaccine must not require refrigeration nor any special skills to administer.

The vaccine’s production uses existing methods to synthesize the amino acid peptides, which are the epitopes themselves. The packaging, however, is a new concept. [Dr. Rubsamen’s] company, Flow Parma, Inc., is using microspheres to encapsulate the vaccine, which render it shelf-stable and allow it to be administered through a nasal spray. Learn more about the technology behind the production of microspheres from this white paper (PDF).

If the vaccine (which will be produced without profit) passes clinical trials, it could see mass distribution as early as 2017.

The $25M we mentioned earlier is a tall hill to climb, but think of the reward if the vaccine is successful. You can donate directly to help reach this goal. If you’re planning on giving gift cards this year, you can purchase them for many different retailers through Gyft, who is donating 100% of December proceeds to the project.