This Smart Watch Keeps An Eye On Ambient CO2 Levels

October 30, 2021 by Lewin Day 20 Comments

Human respiration takes in oxygen and in turn, we exhale carbon dioxide. Thus, an uptick of carbon dioxide levels around us can indicate we’re in the presence of other humans, and also, perhaps, the pathogens they carry. To explore this phenomenon, [C Scott Ananian] developed a mod for the Watchy open-source smartwatch, which lets it detect carbon dioxide.

The idea behind the build is simple. If you’re around increased CO2 levels, it may be because you’re surrounded by people, and thus more likely to be exposed to COVID-19. To detect CO2, the watch relies on a Sensiron SCD40 or SCD41 sensor. This is read by the Watchy’s ESP32 microcontroller, and results are graphed on the watch’s e-Paper display. The Watchy is also given a nice new aluminum case to fit the additional hardware.

It’s cool having a graph on your wrist of the ambient concentration of CO2, and at the very least, it could make a good talking point next time you’re at a particularly boring party. You’ll also be more than ready to advise other partygoers if the carbon dioxide level is reaching dangerous levels.

We’ve seen similar builds before, which are useful not only for pandemic safety but also for monitoring if you have any leaks from CO2 storage in the house. If you’ve been working on your own ways to track dangerous gases, be sure to drop us a line!

PineTime Smartwatch And Good Code Play Bad Apple

October 16, 2021 by Brian McEvoy 11 Comments

PineTime is the open smartwatch from our friends at Pine64. [TT-392] wanted to prove the hardware can play a full-motion music video, and they are correct, to a point. When you watch the video below, you should notice the monochromatic animation maintaining a healthy framerate, and there lies all the hard work. Without any modifications, video would top out at approximately eight frames per second.

To convert an MP4, you need to break it down into images, which will strip out the sound. Next, you load them into the Linux-only video processor, which looks for clusters of pixels that need changing and ignores the static ones. Relevant pixel selection takes some of the load off the data running to the display and boosts the fps since you don’t waste time reminding it that a block of black pixels should stay the way they are. Lastly, the process will compress everything to fit it into the watch’s onboard memory. Even though it is a few minutes of black and white pictures, compiling can take a couple of hours.

You will need access to the watch’s innards, so hopefully, you have the developer kit or don’t mind cracking the seal. Who are we kidding, you aren’t here for intact warranties. The video resides in the flash chip and you have to transfer blocks one at a time. Bad Apple needs fourteen, so you may want to practice on a shorter video. Lastly, the core memory needs some updating to play correctly. Now you can sit back and…watch.

Pine64 had a rough start with the single-board computers, but they’re earning our trust with things like soldering irons and Google-less Linux mobile phones.

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Several shirts side by side, each with a custom design

3D Print A Custom T-Shirt Design, Step-by-Step

October 15, 2021 by Donald Papp 14 Comments

Want to make a t-shirt with a custom design printed on it? It’s possible to use a 3D printer, and Prusa Research have a well-documented blog post and video detailing two different ways to use 3D printing to create colorful t-shirt designs. One method uses a thin 3D print as an iron-on, the other prints directly onto the fabric. It turns out that a very thin PLA print makes a dandy iron-on that can survive a few washes before peeling, but printing flexible filament directly onto the fabric — while more complicated — yields a much more permanent result. Not sure how to turn a graphic into a 3D printable model in the first place? No problem, they cover that as well.

Making an iron-on is fairly straightforward, and the method can be adapted to just about any printer type. One simply secures a sheet of baking paper (better known as parchment paper in North America) to the print bed with some binder clips, then applies glue stick so that the print can adhere. A one- or two-layer thick 3D print will stick to the sheet, which can then be laid print-side down onto a t-shirt and transferred to the fabric by ironing it at maximum temperature. PLA seems to work best for iron-ons, as it preserves details better. The results look good, and the method is fairly simple.

Direct printing to the fabric with flexible filament can yield much better (and more permanent) results, but the process is more involved and requires 3D printing a raised bed adapter for a Prusa printer, and fiddling quite a few print settings. But the results speak for themselves: printed designs look sharp and won’t come loose even after multiple washings. So be certain to have a few old shirts around for practice, because mistakes can’t be undone.

A very thin 3D print makes a decent iron-on that survives a few washes.

A 3D-printed bed adapter enables direct printing onto fabric for better results.

That 3D printers can be used to embed designs directly onto fabric is something many have known for years, but it’s always nice to see a process not just demonstrated as a concept, but documented as a step-by-step workflow. A video demonstration of everything, from turning a graphic into a 3D model to printing on a t-shirt with both methods is all in the short video embedded below, so give it a watch.

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Wearable colour eink display in watch format showing additional internal details

Bendable Colour EPaper Display Has Touch Input Too

October 12, 2021 by Dave Rowntree 8 Comments

The Interactive Media Lab at Dresden Technical University has been busy working on ideas for user interfaces with wearable electronics, and presents a nice project, that any of us could reproduce, to create your very own wearable colour epaper display device. They even figured out a tidy way to add touch input as well. By sticking three linear resistive touch strips, which are effectively touch potentiometers, to a backing sheet and placing the latter directly behind the Plastic Logic Legio 2.1″ flexible electrophoretic display (EPD), a rudimentary touch interface was created. It does look like it needs a fair bit of force to be applied to the display, to be detectable at the touch strips, but it should be able to take it.

The rest of the hardware is standard fayre, using an off-the-shelf board to drive the EPD, and an Adafruit Feather nRF52840 Sense board for the application and Bluetooth functionality. The casing is 3D printed (naturally) and everything can be built from items many of us have lying around. The video below shows a few possible applications, including interestingly using the display as part of the strap for another wearable. Here is also is a report on adding interactive displays to smart watches. After all, you can’t have too many displays.

Many wearables projects can be found in the HaD archives, including this dubious wearable scope, a method for weaving OLED fibres into garments. Finally, for a good introduction to wearable DIY tech, you could do worse than this Supercon talk from Sophy Wong.

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Hackers And China

October 9, 2021 by Elliot Williams 26 Comments

The open source world and Chinese manufacturing have a long relationship. Some fifteen years ago, the big topic was how companies could open-source their hardware designs and not get driven bankrupt by competition from overseas. Companies like Sparkfun, Adafruit, Arduino, Maple Labs, Pololu, and many more demonstrated that this wasn’t impossible after all.

Maybe ten years ago, Chinese firms started picking up interesting hacker projects and producing them. This gave us hits like the AVR transistor tester and the NanoVNA. In the last few years, we’ve seen open-source hardware and software projects that have deliberately targeted Chinese manufacturers, and won. We do the design and coding, they do the manufacturing, sales, and distribution.

But this is something else: the Bangle.js watch takes an essentially mediocre Chinese smartwatch and reflashes the firmware, and sells them as open-source smartwatches to the general public. These pre-hacked watches are being sold on Kickstarter, and although the works stands on the shoulders of previous hacker’s reverse engineering work on the non-open watch hardware, it’s being sold by the prime mover behind the Espruino JavaScript-on-embedded language, which it runs on.

We have a cheap commodity smartwatch, being sold with frankly mediocre firmware, taken over by hackers, re-flashed, re-branded, and sold by the hackers on Kickstarter. As a result of it being (forcibly) opened, there’s a decently sized app store of contributed open-source applications that’ll run on the platform, making it significantly more useful and hacker friendly than it was before.

Will this boost sales? Will China notice the hackers’ work? Will this, and similar projects, end up in yet another new hacker/China relationship? We’re watching.

Hackable Smart Watch Is Also Open Source

October 5, 2021 by Bryan Cockfield 16 Comments

When they first came to market, many detractors thought that smart watches would be a flop or that there wouldn’t be much use for them. Over the past few years, though, their sales continue to increase as people find more and more niche uses for them that weren’t previously considered. The one downside to most of these watches is unsurprisingly their lack of openness and hackability, but with some willpower and small circuit components there are a few options available for those of us who like to truly own our technology.

This smartwatch is the SMA Q3, the next version of this smartwatch that we saw at the beginning of last year. Like its predecessor, it boasts a sunlight-readible display powered by a Bluetooth SoC, but this time uses the upgraded nRF52840. All of the standard smartwatch features are available, but this version also includes SWD pins on the back, and additionally has support for Bangle.js and can run some of the apps from the app loader. Some details still need to be worked out for this specific hardware, but there are some workarounds available for the known problems.

The project is also on Kickstarter right now but is well past its funding goals. We’re excited to see adoption of an open-source smartwatch like this, and to that end all of the hardware details and software are freely available on the project’s page, provided you can order some of the needed parts from overseas. If you’re looking for something a little more BASIC, though, we have you covered there as well.

A shirt with carbon nanotube threads stitched into a shirt monitor the wearer's heart rate.

Sew-able Carbon Nanotube Thread Could Spin A Lot Of Awesome

September 28, 2021 by Kristina Panos 18 Comments

Plenty of people just plain dislike wearing jewelry, even (or especially) smart watches. Nevertheless, they’d like to have biofeedback like everybody else. Well, we watch-less ones have something to look forward to, because a group of graduate students at Rice University have created extremely strong conductive thread woven from carbon nanotubes, which can be sewn into standard athletic clothing and used as electrodes, antennas, or simply as ballistic protection.

At 22 microns wide, the original carbon nanotubes were too skinny to use as thread. Instead, the team braided together three bundles of seven ‘tubes each using the type of machine that model boat builders use to make tiny rigging. Then they zig-zag stitched the threads into a shirt, which gives the stitches added flexibility. This thread maybe as strong and conductive as metal, but the fibers are soft and flexible, and most importantly, machine-washable. Between its strength and conductivity, this thread could have a long list of applications from military down to civilian. Check out the introduction in the video after the break.

For now, the shirt has to be pretty snug, but future garments could easily have higher concentrations of nano-threads in order to get a better signal. Good thing, because we’re still carrying around our COVID nineteen — aka the weight we’ve gained since the longest March of anyone’s life, and never liked tight shirts anyway.

What else can carbon nanotubes do? Plenty, like keep 3D prints from delaminating.

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