37C3: The Tech Behind Life With Quadraplegia

January 9, 2024 by Elliot Williams 21 Comments

While out swimming in the ocean on vacation, a big wave caught [QuadWorker], pushed him head first into the sand, and left him paralyzed from the neck down. This talk isn’t about injury or recovery, though. It’s about the day-to-day tech that makes him able to continue living, working, and travelling, although in new ways. And it’s a fantastic first-hand insight into how assistive technology works for him.

If you can only move your head, how do you control a computer? Surprisingly well! A white dot on [QuadWorker]’s forehead is tracked by a commodity webcam and some software, while two button bumpers to the left and right of his head let him click with a second gesture. For cell phones, a time-dependent scanner app allows him to zero in successively on the X and Y coordinates of where he’d like to press. And naturally voice recognition software is a lifesaver. In the talk, he live-demos sending a coworker a text message, and it’s almost as fast as I could go. Shared whiteboards allow him to work from home most of the time, and a power wheelchair and adapted car let him get into the office as well.

The lack of day-to-day independence is the hardest for him, and he says that they things he misses most are being able to go to the bathroom, and also to scratch himself when he gets itchy – and these are yet unsolved problems. But other custom home hardware also plays an important part in [QuadWorker]’s setup. For instance, all manner of home automation allows him to control the lights, the heat, and the music in his home. Voice-activated light switches are fantastic when you can’t use your arms.

This is a must-watch talk if you’re interested in assistive tech, because it comes direct from the horse’s mouth – a person who has tried a lot, and knows not only what works and what doesn’t, but also what’s valuable. It’s no surprise that the people whose lives most benefit from assistive tech would also be most interested in it, and have their hacker spirit awakened. We’re reminded a bit of the Eyedrivomatic, which won the 2015 Hackaday Prize and was one of the most outstanding projects both from and for the quadriplegic community.

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How To Refrigerate With Urine

January 9, 2024 by Maya Posch 13 Comments

It’s often said that the best science experiments are the ones which do not require any special devices or ingredients, which makes the use of what naturally comes out of one’s body clearly one of the winners. It’s also the beginning of yet another [Hyperspace Pirate] chemistry video that’s both fascinating and unforgettable — this time introducing a considerable collection of urine, and the many uses of the urea in it, including its use for refrigeration.

The respective cooling effect of a variety of compounds in solution. (Credit: Hyperspace Pirate)

As icky as this may sound, it doesn’t even rank in the top ten of quaint things people have historically done with urine, so extracting urea from it is rather benign. This is performed by adding sodium hydroxide to the starting component after heating, which creates gaseous ammonia (NH₃) which was then condensed into its liquid (dissolved) form. In order to create the target compound – being ammonium nitrate – nitric acid (HNO₃) had to be created first.

For this the older, but cheaper and easier Birkeland-Eyde process was used. This uses high-voltage electrical arcs to break down the nitrogen and oxygen in the air and cause the formation of nitric oxide (NO), that subsequently reacts with atmospheric oxygen to form nitrogen dioxide (NO₂). Running the NO₂ through water then creates the desired HNO₃, which can be combined with the ammonia solution to create ammonium nitrate. The resulting solution was then evaporated into solid ammonium nitrate, to use it in an aluminium cooling cylinder, with freshly added water.

This is the simplest way to use the cooling effect of such solutions (pictured), but the benefit of ammonium nitrate over the original urea seems minimal. The low efficiency of this cooling approach means that the next use of urine will involve a much more efficient vapor-absorption cycle, which we’re sure everyone is squeezing their legs together for in anticipation.

We’ve been covering the refrigeration experiments [Hyperspace Pirate] has been conducting for some time now. If you’re into the science of making things cold check out how seashells can be turned into dry ice, or what goes into building a home cryocooler.

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