Hacking out of Necessity — Fixing Your Own CPAP Machine

Fixing a CPAP machine

One of our avid readers named [Felix] suffers from sleep apnea, and needs a CPAP machine in order to not suffocate while he sleeps — After a recent power-outage, his machine broke, so he decided to try his hand at fixing it.

A CPAP (Continuous Positive Airway Pressure) machine ensures people suffering from sleep apnea breath throughout the night, by preventing their throats from closing. As a medical device, they tend to be super expensive, which is why [Felix] wanted to try fixing his (at least until he gets a new machine covered by insurance).

Upon opening up the machine, it was easy to see the problem: the circuit board was completely fried. Luckily, the machine is pretty simple. It has a brushless DC motor (12V), and two chambers with air filters, along with an air pressure sensor. Since the motor is brushless, it’s not quite as simple as just hooking it up to a power supply. It had a whopping 8 separate leads.

[Read more...]

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.

 

Backyard Brains: Controlling Cockroaches, Fruit Flys, And People

[Greg Gage] and some of the other crew at Backyard Brains have done a TED talk, had a few successful Kickstarters, and most surprisingly given that pedigree, are actually doing something interesting, fun, and educational. They’re bringing neuroscience to everyone with a series of projects and kits that mutilate cockroaches and send PETA into a tizzy.

[Greg] demonstrated some of his highly modified cockroaches by putting a small Bluetooth backpack on one. The roach had previously been ‘prepared’ by attaching small electrodes to each of its two front antennas. The backpack sends a small electrical signal to the antennae every time I swiped the screen of an iPhone. The roach thinks it’s hitting a wall and turns in the direction I’m swiping, turning it into a roboroach. We seen something like this before but it never gets old.

Far from being your one stop shop for cockroach torture devices, Backyard Brains also has a fairly impressive lab in the basement of their building filled with grad students and genetically modified organisms. [Cort Thompson] is working with fruit flies genetically modified so a neuron will activate when they’re exposed to a specific pulse of light. It’s called optogenetics, and [Cort] has a few of these guys who have an ‘I’m tasting something sweet’ neuron activated when exposed to a pulse of red light.

Of course controlling cockroaches is one thing, and genetically engineering fruit flies is a little more impressive. How about controlling other people? After being hooked up to an EMG box to turn muscle actuation in my arm into static on a speaker, [Greg] asked for a volunteer. [Jason Kridner], the guy behind the BeagleBone, was tagging along with us, and stepped up to have two electrodes attached to his ulnar nerve. With a little bit of circuitry that is available in the Backyard Brains store, I was able to control [Jason]‘s wrist with my mind. Extraordinarily cool stuff.

There was far too much awesome stuff at Backyard Brains for a video of reasonable length. Not shown includes projects with scorpions, and an improved version of the roboroach that gives a roach a little bit of encouragement to move forward. We’ll put up a ‘cutting room floor’ video of that a bit later.

Open Source Glucose Monitoring on the Front Lines of Innovation

Cloud-based CGM

[John] is the parent of a diabetic child, and his efforts to expand the communication options for his son’s CGM (continuous glucose monitor) have grown into a larger movement: #wearenotwaiting.

After receiving a new monitor—a Dexcom G4—[John] set about decoding its communication protocols. The first steps were relatively simple, using a laptop to snag the data from the CGM and storing it on a Google doc which he could access as the day went along. The next step involved connecting the monitor and a cellphone for around-the-clock data gathering. [John] managed to develop an Android app to accomplish just that, and shortly after people began to take notice. Both [Howard Look], the CEO of Tidepool, and [Lane Desborough], engineer and father of a child with diabetes, have thrown in their support, leading to further developments such as Nightscout, an open source solution for storing CGM data in the cloud.

This project is a victory not only for those with diabetes, but also for the open source community. [John] admits his initial hesitation for developing for the medical device platform: litigation from a corporation could cause devastation for him and his family despite his intentions to merely improve his son’s and others’ quality of life. Those fears have mostly subsided, however, because the project now belongs to both no one and to everyone. It’s community-owned through an open source repository. Check out the overview of [John's] work for more pictures and links to different parts of the #wearenotwaiting community.

Converting CTs and MRIs Into Printable Objects

skullPeople get CT and MRI scans every day, and when [Oliver] needed some medical diagnostic imaging done, he was sure to ask for the files so he could turn his skull into a printable 3D object.

[Oliver] is using three different pieces of software to turn the DICOM images he received from his radiologist into a proper 3D model. The first two, Seg3D and ImageVis3D, are developed by the University of Utah Center for Integrative Biomedical Computing. Seg3D stitches all of the 2D images from an MRI or CT scan into a proper 3D format. ImageVis3D allows [Oliver] to peel off layers of his flesh, allowing him to export a file of just his skull, or a section of his entire face. The third piece of software, MeshMixer, is just a mesh editor and could easily be replaced with MeshLab or Blender.

[Oliver] still has a lot of work to do on the model of his skull – cleaning up the meshes, removing his mandible, and possibly plugging the top of his spinal column if he would ever want to print a really, really awesome mug. All the data is there, though, ready for digital manipulation before sending it off to be printed.

[Read more...]

Bluetooth Headphones For Hearing Aids

hearing

Cyborgs walk among us, but for the time being, it’s really only people with glasses, contact lenses, the occasional hearing aid and the infrequent prosthesis. As with all technology, these devices can be expanded into something they were not originally designed to do – in [Gertlex]‘ case, the superpower of listening to music through his hearing aids. he gets a few strange looks from wearing a Bluetooth headset around his neck, but the power to turn his hearing aids ito what are effectively in-ear monitors is a great application of modified electronics.

[Gertlex] began with a Bluetooth headset, his hearing aid, a few resistors, some wire, a 3.5mm audio connector, and an absurdly expensive DAI cable. The DAI cable – Direct Audio Input – is a pseudo-standardized feature on many hearing aids. as its name implies, it allows the wearer of a hearing aid to pipe audio directly into their ear.

By cutting up one of these $50+ DAI cables, [Gertlex] was able to construct a DAI to 3.5mm adapter cable. From there, it was simply a matter of installing a 3.5mm socket on a Bluetooth headset.

It’s a brilliant build, with the most expensive component being the DAI connector itself. [Gertlex] has a few ideas for making these connectors himself – they’re really only three pins and some plastic – and we’re hoping he gets around to that soon.

 

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!

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