Hackaday Prize Entry: Open-source Pulse Oximetry

Chances are pretty good you’ve had a glowing probe clipped to your fingertip or earlobe in some clinic or doctor’s office. If you have, then you’re familiar with pulse oximetry, a cheap and non-invasive test that’s intended to measure how much oxygen your blood is carrying, with the bonus of an accurate count of your pulse rate. You can run down to the local drug store or big box and get a fingertip pulse oximeter for about $25USD, but if you want to learn more about photoplethysmography (PPG), [Rajendra Bhatt]’s open-source pulse oximeter might be a better choice.

PPG is based on the fact that oxygenated and deoxygenated hemoglobin have different optical characteristics. A simple probe with an LED floods your fingertip with IR light, and a photodiode reads the amount of light reflected by the hemoglobin. [Rajendra]’s Easy Pulse Plugin receives and amplifies the signal from the probe and sends it to a header, suitable for Arduino consumption. What you do with the signal from there is up to you – light an LED in time with your heartbeat, plot oxygen saturation as a function of time, or drive a display to show the current pulse and saturation.

We’ve seen some pretty slick DIY pulse oximeters before, and some with a decidedly home-brew feel, but this seems like a good balance between sophisticated design and open source hackability. And don’t forget that IR LEDs can be used for other non-invasive diagnostics too.

The 2015 Hackaday Prize is sponsored by:

Arduino Radar Watches You Breathe

We’ve all likely watched an episode of “Star Trek” and admired the level of integration on the sick bay diagnostic bed. With its suite of wireless sensors and flat panel display, even the 1960s imagining of the future blows away the decidedly wired experience of a modern-day ICU stay. But we may be getting closer to [Dr. McCoy]’s experience with this radar-based respiration detector.

[Øyvind]’s build, which takes the origin of the term “breadboard” to heart, is based on a not-inexpensive Xethru module, which appears to be purpose-built for detecting respiration. The extra-thick PC board seems to house the waveguides internally, which is a neat trick but might limit how the module can be deployed. The module requires both a USB interface and level shifter to interface the 2.8V levels of the module to the 5V Arduino Uno. In the video below, [Øyvind]’s prototype simply lights an RGB LED in response to the chest movement it detects, but there’s plenty of potential for development here. We’ve seen a laser-based baby breathing monitor before; perhaps this systems could be used to the same end without the risk of blinding your tyke. Or perhaps better diagnostics for sleep apnea patients than an intrusive night in a sleep study lab.

Clocking in at $249 for the sensor board and USB interface, this build is not exactly for the faint of heart or the light of wallet. But as an off-the-shelf solution to a specific need that also has a fair bit of hacking potential, it may be just the thing for someone. Of course if radar is your thing, you might rather go big and build something that can see through walls.

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We Should 3D Scan People

In a perfect futuristic world you have pre-emptive 3D scans of your specific anatomy. They’d be useful to compare changes in your body over time, and to have a pristine blueprint to aid in the event of a catastrophe. As with all futuristic worlds there are some problems with actually getting there. The risks may outweigh the rewards, and cost is an issue, but having 3D imaging of a sick body’s anatomy does have some real benefits. Take a journey with me down the rabbit hole of 3D technology and Gray’s Anatomy.

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The Biohacking Movement And Open Source Insulin

In March of 2014, I knew my eight year old daughter was sick. Once borderline overweight, she was now skeletally thin and fading away from us. A pre-dawn ambulance ride to the hospital gave us the devastating news – our daughter had Type 1 diabetes, and would be dependent on insulin injections for the rest of her life.

This news hit me particularly hard. I’ve always been a preparedness-minded kind of guy, and I’ve worked to free myself and my family from as many of the systems of support as possible. As I sat in the dark of the Pediatric ICU watching my daughter slowly come back to us, I contemplated how tied to the medical system I had just become. She was going to need a constant supply of expensive insulin, doled out by a medical insurance system that doesn’t understand that a 90-day supply of life-saving medicine is a joke to a guy who stocks a year supply of toilet paper. Plus I had recently read an apocalyptic novel where a father watches his 12-year old diabetic daughter slip into a coma as the last of her now-unobtainable insulin went bad in an off-grid world. I swore to myself that I’d never let this happen, and set about trying to find ways to make my own insulin, just in case.

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University Peristaltic Pump Has Hacker Heritage

A team at [Vanderbilt University] have been hacking together their own peristaltic pumps. Peristaltic pumps are used to deliver precise volumes of fluid for research, medical and industrial applications. They’re even occasionally used to dose fish tanks.

pumpThey work by squeezing the fluid in a flexible tube with a series of rollers (check out the awesome gif from Wikipedia to the right). We’ve seen 3D printed peristaltic pumps before, and cheap pumps have been appearing on eBay. But this build is designed to be lab grade, and while the cheap eBay devices can deliver ~20ml/min this one can deliver flow rates in the microliter/min range. It also has a significant cost advantage over commercial research grade pumps which typically cost thousands of dollars, each of these pumps costs only fifty bucks.

The pump has a clear hacker heritage, using an Arduino Uno, Adafruit Motor shield, and 3D printed mechanical parts. So it’s particularly awesome that they’ve also made their design files and Arduino code freely available!

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Hackaday Prize Entry: Online Bone Marrow Cytometry Aid

Simple blood tests can lead a doctor toward a diagnosis of blood cancers, like leukemia, lymphoma and myeloma, but to really see what’s going on, he or she needs to go to the source of the problem: the bone marrow. Examining maturing blood cells from the marrow with a microscope is an important step in staging the disease and developing a plan for treatment, but it’s a tedious and error-prone process that requires a doctor to classify and tally a dozen or so different cells based on their size, shape and features. Automated systems like flow cytometry and image analysis software can help, but in an austere environment, a doctor might not have access to these. Luckily, there’s now an on-line app to assist with bone marrow cytometry.

Thanks to [Eduardo Zola], a doctor can concentrate on classifying cells without looking up from the microscope, and without dictating to an assistant. Keys are assigned to the different cell morphologies, and a running total of each cell type is kept. With practice, the doctor should be able to master the keying for the various cells; we suspect the generation of physicians that grew up with the WASD keying common in PC-based gaming might have a significant advantage over the older docs when it comes to learning such an app.

[Eduardo]’s app seems like a simple way to improve on an important medical procedure, and an enabling technology where access to modern instrumentation is limited. To that end, one area for improvement might be a standalone app that can run on a laptop without internet access, or perhaps even a version that runs on a smart phone. But even as it is, it’s a great entry for the 2015 Hackaday Prize.

The 2015 Hackaday Prize is sponsored by:

Pump Up The Volume With The 3D Printed Syringe Pump Rack

Syringe pumps are valuable tools when specific amounts of fluid must be dispensed at certain rates and volumes. They are used in many ways, for administering IV medications to liquid chromatography (LC/HPLC). Unfortunately, a commercial pump can cost a pretty penny. Not particularly thrilled with the hefty price tag, [Aldric Negrier] rolled up his sleeves and made a 3D-printed version for 300 USD.

[Aldric] has been featured on Hackaday before, so we knew his latest project would not disappoint. His 3D Printed Syringe Pump Rack contains five individual pumps that can operate independently of each other. Five pieces are 3D-printed to form the housing for each pump. In addition, each pump is composed of a Teflon-coated lead screw, an Arduino Nano V3, a Pololu Micro stepper motor driver, and a NEMA-17 stepper motor. The 3D Printed Syringe Pump Rack runs on a 12V power supply using a maximum of 2 amps per motor.

While the standard Arduino IDE contains the Stepper library, [Aldric] wanted a library that allowed for more precise control and went with the Accelstepper library. The 3D Printed Syringe Pump Rack has a measured accuracy of 0.5µl in a 10ml syringe, which is nothing to laugh at.

Syringe pump racks like [Aldric’s] are another great example of using open source resources and the spirit of DIY to make typically expensive technologies more affordable to the smaller lab bench. If you are interested in other open source syringe pump designs, you can check out this entry for the 2014 Hackaday Prize.

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