A handful of parts used to form an Electrocardiogram

minimal-ecg

It’s difficult to image a more bare-bones approach to building an ECG. [Raul] used an Arduino nano to collect samples and push them to a computer for graphing.

An Electrocardiogram measures electrical activity around your heart. The white circles above are the sensors which he picked up in a box of fifty for 11 Euros (under $15). Stick them on your skin in just the right places and they’ll report back on what your heart is doing.

He used a AD8221 to amplify the signals. He mentions that this is an ins-amp, not an op-amp. We didn’t find a concise reference explaining what that is. It might be a good topic for the comments section. The signal from that chip feeds into an LM324 op-amp before being dumped into the Arduino.

Simplicity comes at a price. This measures very small electrical impulses and has very little in the way of shielding and filtering. Because of this you may need to do a rain dance, say a prayer, burn a candle, and stick needles into a doll to get a reliable signal on the other end.

Here’s another version that doesn’t require special sensors.

Measuring ketosis with an Arduino

key

A bit of biology and nutrition before we roll into this: Ketosis is when your body runs on fat reserves instead of carbohydrates. This is the basis of diets such as Atkins, and despite the connotations of eating hamburger patties and butter, you can actually lose weight on these diets. One problem with a keto diet is the difficulty of measure how many ketones your liver is processing; this can be done with a urine sample, but being able to measure small amounts of acetone in your breath would be the ideal way to measure ketosis. [Jens] came up with a device that does just that. It’s called Ketosense, and it will tell you how well your keto diet is doing by just having you blow into a sensor.

[Jens]‘ device consists of an Arduino, LCD display, and two sensors – one for acetone, and another for temperature and humidity. By carefully calibrating a TGS822 sensor, [Jens] was able to measure the acetone content of an exhaled breath along with temperature and pressure. This gave him a reading in parts per million, and with a short bit of math was able to convert that into something that made sense when talking about ketosis, mmol/l.

Without access to a lab that can measure blood ketone levels, it’s difficult to say if [Jens] device really works as intended. If he were to find his way into a lab, though, it would be possible to correlate his sensor’s values with blood ketone results and improve the accuracy of his sensor.

Building an IR mouse interface for the disabled

[Chris Young] has a physical disability that means he can’t use a mouse very well. He typically uses Dragon Naturally Speaking for moving his mouse using voice commands but has found that it lacks some features he needs and can crash at times.

His solution to this problem was to create a device that will translate IR signals from a simple remote into mouse actions and movements. He is using an Arduino micro for this task, and as you can see in the video it seems to have worked out well for him. He has code and schematics available on his site if you would like to recreate this yourself.

[Chris] has actually built several accessibility devices for himself and others. You should check out his blog for more, including his thoughts on the cost of commercial accessibility equipment vs DIY. If you think you would like to try making a device to help someone with a physical disability access a computer, hop on over to thecontrollerproject.com and join up on the forums.

 

via thecontrollerproject.com

[Ricky's] rugged DVD player

1Ge9hh

[Ricky] absolutely loves watching DVDs. He is epileptic and is cognitively functioning at a level roughly that of a 6 year old.  His younger brother [Ronnie] noticed that [Ricky's] DVDs as well as his DVD player never lasted very long due to some rough handling. [Ronnie] stepped up to make [Ricky's] life just a little bit easier by building this super rugged DVD watching station.

He started by ripping out the front pcb of the DVD player that has all the buttons. [Ricky] can wear through a set of standard buttons in no time, so [Ronnie] extended these to arcade buttons. Then he mounted everything into a custom cabinet that can withstand a considerable amount of abuse.

Now they can load 5 disks in and [Ricky] can watch what he pleases without worry of destroying the player.

[Ronnie] mentioned that he’d like to make a more complex control system using some kind of microcontroller, but frankly I find the simplicity of this to be perfect. Maybe a media pc loaded with movies might be a decent next step. You can see [Ronnie's] build log here.

If you’ve ever considered making something like this to improve someone’s life, you should check out thecontrollerproject.com where people with special needs can connect with people who can build interfaces.

Building custom game controllers for people with physical disabilities

Hold on tight. This is going to be a long post. I kept my temper in the video, but here I can just come out and let you know that I’m livid. Every time I start thinking about this, I feel so angry and helpless that my face gets hot and my hands get shaky.  I’m getting ahead of myself though, so lets just back up a little bit and talk about a pretty cool kid named [Thomas].

[Thomas] has muscular dystrophy. This means he’s going to gradually lose strength and control in his muscles over time. He has already lost his ability to stand, and even holding buttons on a game-pad for extended times can be difficult. Gaming, as you can imagine, is very important to [Thomas] and people like him. It offers a release of frustration, like it does for all of us, but also a level playing ground. When he’s in the game, he’s like everyone else.

[Read more...]

Modeling squid cells in code foregoes connecting voltage to animals

squid-cells-processing

[Kemper Smith] built a little piece of nature in Processing. He was inspired by a biology experiment that excited squid cells using electricity. The result is an interactive display that mimics that biology.

Last August we saw a peculiar experiment that forced Cyprus Hill music on the color changing cells of a squid. The cells make colors by stretching sacs of pigment; the larger they get the more of that color is shown. Normally this is used for camouflage. The image on the left is the reaction from connecting headphone wires while music is being played.

But we can’t all get our hands on this type of wet-ware — especially if life far inland. So [Kemper] got to work writing some Processing code. The result is seen on the right. It does a good job of replicating the motion and color palette of the original. He’s put together a web-based demonstration which you can interact with using your mouse cursor. But we also saw him demonstrate a Kinect based version at our local hackerspace.

[Read more...]

Superbly built walking cane

cane

This cane is fairly simple, and very beautiful. [Bill Lewey] made this and was nice enough to document the entire process in detail. There are tons of pictures of the build for you to ogle over, from cutting the rough shape all the way to the finish.

I’ve include a few of the images below, but you should really go to his site for all the details, you won’t be sorry.