Infant is wearing sensor vest as she is held by her mom. ECG, respiration, and accelerometry data is also showing.

Open Source Wearables For Infants

We’ve seen plenty of hacks that analyze biometric signals as measures of athletic performance, but maybe not as many hacks that are trying to study behavior. Well, that’s exactly what developmental psychologists at Indiana University and the University of East Anglia have done with their open-source, wireless vest for measuring autonomic function in infants.

infant biosensor vest for heart rate, motion, and respiratory rateTheir device includes a number of components we’ve seen already. There is an HC-05 Bluetooth module, AD8232 electrocardiography (ECG) analog front-end, LIS3DH 3-axis accelerometer, MCP73831 LiPo charger, a force-sensitive resistor for measuring respiration, and a Teensy microcontroller. Given how sensitive an infant’s skin can be, they opted for fabric electrodes for the ECG instead of those awful sticky ones that we’re accustomed to. They then interfaced the conductive fabric with copper plates using snap fasteners (or press studs or snap buttons, whichever terminology you’re more familiar with). The copper plates were connected to the circuit board using standard electrical wire. Then, they embedded the sensors into a vest they sewed together themselves. It’s basically a tiny weighted vest for infants but it seems well-padded enough to be somewhat comfortable.

They did a short test analyzing heart and breathing rates during a period of “sustained attention,” basically when you’re quietly fixated on a single object or activity for a period of a few minutes or longer. They were really pleased with the vest’s ability to collect consistent data and noted that heart and respiratory rate variability decreased during the sustained activity test, which was an expected outcome. Apparently, when you’re pretty fixated on a singular task, your body naturally calms down, so to speak, and the variability in some of your physiological responses decreases. Well, unless someone slowly walks up behind you and pinches you, of course.

They provided detailed instructions for recreating the vest, so be sure to check those out. They probably want their device to look a lot less than body armor though. Maybe the Sewbo can help them out with their next iteration.

A family of PixMob bracelets being coltrolled by an ESP32 with an IR transmitter attached to it. All the bracelets are shining a blue-ish color

PixMob Wristband Protocol Reverse-Engineering Groundwork

The idea behind the PixMob wristband is simple — at a concert, organizers hand these out to the concertgoers, and during the show, infrared projectors are used to transmit commands so they all light up in sync. Sometimes, attendees would be allowed to take these bracelets home after the event, and a few hackers have taken a shot at reusing them.

The protocol is proprietary, however, and we haven’t yet seen anyone reuse these wristbands without tearing them apart or reflashing the microcontroller. [Dani Weidman] tells us, how with [Zach Resmer], they have laid the groundwork for reverse-engineering the protocol of these wristbands.

Our pair of hackers started by obtaining a number of recordings from a helpful stranger online, and went onto replaying these IR recordings to their wristbands. Most of them caused no reaction – presumably, being configuration packets, but three of them caused the wristbands to flash in different colors. They translated these recordings into binary packets, and Dani went through different possible combinations, tweaking bits here and there, transmitting the packets and seeing which ones got accepted as valid. In the end, they had about 100 valid packets, and even figured out some protocol peculiarities like color animation bytes and motion sensitivity mode enable packets.

The GitHub repository provides some decent documentation and even a video, example code you can run on an Arduino with an IR transmitter, and even some packets you can send out with a  Flipper Zero. If you’re interested in learning more about the internals of this device, check out the teardown we featured back in 2019.

Build Your Own 3D Printed Bluetooth Headphones

A few years back, [Shannon Ley] wondered how hard it would be to build a pair of Bluetooth headphones from scratch. Today, we have our answer. The Homebrew Headphones website is devoted to just one thing: explaining how you can use common components and some 3D printed parts to build an impressively comprehensive pair of wireless headphones for around $50 USD.

The headphones pair a CSR8645 Bluetooth audio receiver with a TP4056 USB-C charging module, a 500 mAh LiPo pouch battery, a pair of Dayton Audio CE38MB-32 drivers, and replacement ear covers designed for the Bose QuietComfort QC15. Some perfboard, a couple buttons, a resistor, and an LED round out the parts list.

All of the components fit nicely into the meticulously designed 3D printed frame, and assembly is made as simple as possible thanks to an excellent step-by-step guide. It’s all so well documented that anyone with even basic soldering experience should be able to piece it together without too much fuss.

Of course, these aren’t the first 3D printed headphones we’ve ever seen. But the quality of the documentation and attention to detail really make these stand out.

Cool Face Mask Turns Into Over-Engineered Headache

Seeing his wife try to use a cool face mask to get through the pain of a migraine headache, [Sparks and Code] started thinking of ways to improve the situation. The desire to save her from these debilitating bouts of pain drove him to make an actively cooled mask, all the while creating his own headache of an over-engineered mess.

Void spaces inside the printed mask are filled with chilled water.

Instead of having to put the face mask into the refrigerator to get it cold, [Sparks and Code] wanted to build a mask that he could circulate chilled water through. With a large enough ice-filled reservoir, he figured the mask should be able to stay at a soothing temperature for hours, reducing the need for trips to the fridge.

[Sparks and Code] started out by using photogrammetry to get a 3D model of his wife’s face. Lack of a compatible computer and CUDA-enabled GPU meant using Google Cloud to do the heavy lifting. When they started making the face mask, things got complicated. And then came the unnecessary electronics. Then the overly complicated  and completely unnecessary instrumentation. The… genetic algorithms? Yes. Those too.

We won’t spoil the ending — but suffice it to say, [Sparks and Code] learned a cold, hard lesson: simpler is better! Then again, sometimes being over-complicated is kind of the point such as in this way-too-complex gumball machine.

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OpenJewelry, No Pliers Required

They say that if you want something done right, you gotta do it yourself. Oftentimes, that goes double for getting something done at all. Whereas some people might simply lament the lack of a (stable) Thingiverse-type site for, say, jewelry designs, those people aren’t Hackaday’s own [Adam Zeloof]. With nowhere to share designs among engineering-oriented friends, [Adam] took the initiative and created OpenJewelry, a site for posting open-source jewelry and wearable art designs as well as knowledge about techniques, materials, and processes.

[Adam] has seeded the site with a handful of his own beautiful designs, which run the gamut from traditional silversmithing techniques to 3D printing to fancy PCBs with working blinkenlights. You really should check it out, and definitely consider contributing.

Even if you don’t have any jewelry designs to share, the code is open as well, or you could even edit the wiki. Just be sure to read through the contribution guidelines first. If you don’t have the time for any of that, donations are welcome as well to help maintain the site.

We love wearable art around here, especially when it serves another purpose like this UV-sensing talisman, or this air quality necklace.

The Casio Smartwatch You Never Had

In a way, you have to feel a bit sorry for the engineers at Casio. They can produce the most advanced digital watches ever to grace the wrist, but their work will forever be associated with one of their more lowly creations. The Casio F91 is the archetypal digital watch — it’s affordable, it’s been in production since the Ark, it does the job so well that it’s become a design classic, and it remains a very tough act to follow.

If it has a flaw though, it’s that the functions of a watch from 1989 are very basic. Wouldn’t it be nice if a Casio F91 could be a modern smartwatch! Well thanks to [Pegor] it can, with a complete re-engineering of the classic watch’s internals. Now the simple classic timepiece is fully up-to-date!

All the Casio internals are removed, and a new movement holder supports a fresh PCB with an OLED display mounted via a flexible sub-PCB. The brains comes courtesy of a Texas Instruments CC2640 BLE microcontroller. This gives it a 15-day battery life, which is nothing like what the original watch would have but compares favorably to smartwatches. He admits that the software needs some work, but with hardware this well-executed we hope that others can contribute some improvements.

This is probably the most impressive F91 hack we’ve seen, but it’s by no means the first revamped Casio we’ve shown you.