Sound Card ADCs For Electrocardiograms

Every few years, or so we’re told, [Scott] revisits the idea of building an electrocardiogram machine. This is just a small box with three electrodes. Attach them to your chest, and you get a neat readout of your heartbeat. This is a project that has been done to death, but [Scott]’s most recent implementation is fantastic. It’s cheap, relying on the almost absurd capability for analog to digital conversion found in every sound card, and the software is great. It’s the fit and finish that makes this project shine.

The hardware for this build is simply an AD8232, a chip designed to be the front end of any electrocardiogram. This is then simply connected to the microphone port of a sound card through a 1/8″ cable. For the exceptionally clever, there’s a version based on an op-amp. It’s an extraordinarily simple build, but as with all simple builds the real trick is in the software. That’s where this project really shines, with custom software with graphics, and enough information being displayed to actually tell you something.

We’ve seen a number of sound card ADCs being used for electrocardiograms in the past, including some from the Before Times; it makes sense, sound cards are the cheapest way to get a lot of analog data very quickly. You can check out [Scott]’s demo video out below.

Continue reading “Sound Card ADCs For Electrocardiograms”

Toilet Seat Could Save Your Ass

Our morning routine could be appended to something like “breakfast, stretching, sit on a medical examiner, shower, then commute.” If we are speaking seriously, we don’t always get to our morning stretches, but a quick medical exam could be on the morning agenda. We would wager that a portion of our readers are poised for that exam as they read this article. The examiner could come in the form of a toilet seat. This IoT throne is the next device you didn’t know you needed because it can take measurements to detect signs of heart failure every time you take a load off.

Tracking heart failure is not just one test, it is a buttload of tests. Continuous monitoring is difficult although tools exist for each test. It is unreasonable to expect all the at-risk people to sit at a blood pressure machine, inside a ballistocardiograph, with an oximeter on their fingers three times per day. Getting people to browse Hackaday on their phones after lunch is less of a struggle. When the robots overthrow us, this will definitely be held against us.

We are not sure if this particular hardware will be open-source, probably not, but there is a lesson here about putting sensors where people will use them. Despite the low rank on the glamorous scale, from a UX point of view, it is ingenious. How can we flush out our own projects to make them usable? After all, if you build a badass morning alarm, but it tries to kill you, it will need some work and if you make a gorgeous clock with the numbers all messed up…okay, we dig that particular one for different reasons.

Via IEEE Spectrum.

Simple ECG Proves You Aren’t Heartless After All

We don’t think of the human body as a piece of electronics, but a surprising amount of our bodies work on electricity. The heart is certainly one of these. When you think about it, it is pretty amazing. A pump the size of your fist that has an expected service life of nearly 100 years.

All that electrical activity is something you can monitor and–if you know what to look for–irregular patterns can tell you if everything is OK in there. [Ohoilett] is a graduate student in the biomedical field and he shares some simple circuits for reading electrocardiogram (ECG) data. You can see a video fo the results, below.

Continue reading “Simple ECG Proves You Aren’t Heartless After All”

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.
Continue reading “All About Biosignals”

Saving Lives With Open-Source Electrocardiography

A few months ago, MobilECG wowed us with a formidable electrocardiograph (ECG, also EKG) machine in the format of a business card, complete with an OLED display. We’ve seen business card hacks before, but that was the coolest. But that’s peanuts compared with the serious project that it supports: making an open-source ECG machine that can actually save lives by being affordable enough to be where it’s needed, when it’s needed.

The project, MobilECG, is an open-source, wearable device that supports all of the major ECG modes. In their talk, [Péter Isza] and [Róbert Csordás] taught us a lot about what that exactly entails and how the heart works. We learned a lot, and we’ll share some of that with you after the break.

Continue reading “Saving Lives With Open-Source Electrocardiography”

Android Based Wireless ECG

ECG

The title of [Nuclearrambo’s] post says it all, “Android based wireless ECG monitoring (Temperature sensor and glucometer included).” Wow! What a project!

The project is built around the HC-06 bluetooth module and the Stellaris LaunchPad from TI, an inexpensive ARM developer kit. Building an ECG is a great way to learn about instrumentation amplifiers, a type of differential amplifier used for its extremely high common mode rejection ratio (CMRR). Please be sure to keep in mind that there are a myriad of safety issues and regulation concerns for medical device, and there is no doubt that an ECG is considered a medical device. Sadly, [Nuclearrambo’s] post does not include all of the code and design files you need to build the system, which is understandable considering this is a medical device. That being said, he provides a lot of information about building high-quality ECG instrumentation and the web interface.

It would be great if [Nuclearrambo] could post the Android application code and Stellaris LaunchPad code. Even with these omissions, this post is still worth reading. Designing medical devices requires a lot of know-how, but who knows, maybe your next project can save your life!

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!

Continue reading “Arduino Powered ECG Informs Users Of Their Death”