Wearable Hacks

796 Articles

Wearable Sensors On Your Skin

November 7, 2020 by 10 Comments

An international team at Penn State led by [Larry Cheng] made a breakthrough in printing sensors directly on skin without heat. The breakthrough here is the development of a room-temperature sintering technique. Typical sintering of copper happens at 300 C, and can be further lowered to 100 C by adding nanoparticles. But even 100 C is too hot, since skin starts to burn at around 40 C.

You can obtain their journal article if you want the details, but basically their technique combines the ingredients in peelable face masks and eggshells. With this printed circuit is applied to the skin, the sintering process only requires a hair dryer on the cool setting, and results can bend and fold without breaking the connections. A hot shower will remove the circuit without damaging the circuit or your skin. [Larry] says the circuits can be recycled.

They are using these sensors to monitor temperature, humidity, blood oxygen levels, and heart performance indicators. They’ve even linked these various on-body sensors with a WiFi network for ease of monitoring. After reading this report, we’re left wondering, if the sensor is directly on your skin, can it be really called wearable?

We’ve written about printable inks before, but for printed circuit board applications.  We can’t help but wonder if this technology would help solve some problems inherent in that technology, as well. Thanks to [Qes] for the tip.

Tracking Your Run Over The Long Haul

October 9, 2020 by 5 Comments

The rise of smartphone and smartwatch fitness tracking has been an absolute boon for anyone interested in tracking their runs. However, it all falls short when you need a custom feature and start getting into serious long distance running, as most smartphone batteries simply won’t last. While there are devices out there for the ultra-running enthusiast, [Ivor Hewitt] decided he wasn’t willing to pay a monthly subscription for the pricy trackers or deal with the hassle of the generic cheap versions, and decided to roll his own.

The key pieces of this project are the A9G GPS module and the RDA8955 GRS/GPRS module. They’re both incredibly small and power efficient, perfect for a project that needs to be worn on your person with a long battery life. As an added bonus, the RDA8955 also includes a SoC that’s user-programmable. After battling the lackluster documentation and tooling, [Ivor] managed to get some software running on his new system. A power bug on the A9G GPS module was potentially show stopping, but thanks to some help by folks in the community, it was diagnosed and solved.

Further additions included adding a proper charging circuit (TP4056) and a beefy 2600 mAh battery scavenged from a Sony smartphone, giving the compact system around 38 hours of active battery life. An OLED screen was added to show upcoming aid stations and overall system status, driven by a custom display library. A snazzy translucent case makes the whole device slim and easy to carry. Now at the end of a long race or training session, [Ivor] has a wealth of tracked points that has already been uploaded to his own tracking website and a fully charged phone.

Next time you’re looking for a small compact GPS tracker or cellular logger take a look at this project’s code on GitHub or the A9G and RDA8955 modules.

Thanks [Ivor] for sending this one in!

Making A Halloween Costume Fit For 2020

October 6, 2020 by 13 Comments

All across the country, parents are wondering what to do about the upcoming Trick Or Treat season. Measures such as social distancing, contact free treats, or simply doing it at home are all being weighed as a balance of fun and safety. [BuildXYZ] has decided to lean into the challenges this year and incorporate a mask as part of the costume for his boys.

It started with a 3d printed mask, printed in two halves, and sealed with silicon caulk and N95 filter material in the inlet and outlet holes on the sides. The real magic of the mask is the small OLED screen mounted to the front that works along with a small electret microphone inside the mask. By sampling the microphone and applying a rolling average, the Arduino Nano determines if the mouth drawn on the display should be open or closed. A small battery pack on a belt clip (with a button to flash “Trick or Treat” on the screen) powers the whole setup and can be easily hidden under a cape or costume.

This isn’t the first hack we’ve seen for Halloween this year, such as this socially distant candy slide. We have a feeling that there will be many more as the month rolls on and people start to apply their ingenuity to the season.

Continue reading “Making A Halloween Costume Fit For 2020” →

Seek And Ye Shall Command

October 2, 2020 by 3 Comments

If we count all the screens in our lives, it takes a hot minute. Some of them are touchscreens, some need a mouse or keyboard, but we are accustomed to all the input devices. Not everyone can use the various methods, like cerebral palsy patients who rely on eye-tracking hardware. Traditionally, that only works on the connected computer, so switching from a chair-mounted screen to a tablet on the desk is not an option. To give folks the ability to control different computers effortlessly [Zack Freedman] is developing a head-mounted eye-tracker that is not tied to one computer. In a way, this is like a KVM switch, but way more futuristic. [Tony Stark] would be proud.

An infrared detector on the headset identifies compatible screens in line of sight and synchs up with its associated HID dongle. A headset-mounted color camera tracks the head position in relation to the screen while an IR camera scans the eye to calculate where the user is focusing. All the technology here is proven, but this new recipe could be a game-changer to anyone who has trouble with the traditional keyboard, mouse, and touchscreen. Maybe QR codes could assist the screen identification and orientation like how a Wii remote and sensor bar work together.

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Circuit Board Origami Puts You Face-to-Face With Low-Poly Electronics

September 21, 2020 by 16 Comments

Paper craft has been around almost as long as paper itself. It’s fun to mimic paper craft and origami with low-poly 3D prints, and [Stephen Hawes] wondered whether it could be done with copper-clad PCBs. Two years after the question arose, we have the answer in the form of a fantastical mask with light-up eyes. Check it out in the video below.

[Stephen] started with a model (Update: [kongorilla]’s 2012 low poly mask model from back in 2012 was the starting point for this hack) from the papercraft program Pepakura Designer, then milled out dozens of boards. Only a few of them support circuitry, but it was still quite the time-consuming process. The ATmega32U4 on the forehead along with the fold-traversing circuitry serve to light up the WS2812B eyes. Power runs up the copper tube, which doubles as a handy mounting rod to connect to the 3D printed base.

Continue reading “Circuit Board Origami Puts You Face-to-Face With Low-Poly Electronics” →

E4 Empatica device for measuring location, temperature, skin conductance, sleep, etc. on arm

Choosing The Optimal Sampling Rate For Your DIY Heart Rate Monitor

September 3, 2020 by 19 Comments

With wearables still trying to solidify themselves in the consumer health space, there are a number of factors to consider to improve the reliability of such devices in monitoring biometrics. One of the most critical such parameters is the sampling rate. By careful selection of this figure, developers can minimize errors in the measurement, preserve power, and reduce costs spent on data storage. For this reason, [Brinnae Bent] and [Dr. Jessilyn Dunn] wanted to determine the optimal sampling rate for wrist-worn optical heart rate monitors. We’ve shared their earlier paper on analyzing the accuracy of consumer health devices, so they’ve done a lot of work in this space.

The results of their paper probably don’t surprise anyone. The lower the sampling rate, the lower the accuracy of the measurement, and the higher the sampling rate the more accurate the measurement when compared to the gold standard electrocardiogram. They also found that metrics such as root mean square of successive differences (RMSSD), used for calculating heart rate variability, requires sampling rates greater than 64 Hz, the nominal sampling rate of the wearable they were investigating and of other similar devices. That might suggest why your wearable is a bit iffy when monitoring your sleeping habits. They even released the source code for their heart rate variability analysis, so there’s a nice afternoon read if you were looking for one.

What really stood out to us about their work is how they thoroughly backed up their claims with data. Something crowdfunding campaigns could really learn from.

A Tongue Operated Human Machine Interface

August 6, 2020 by 10 Comments

For interfacing with machines, most of us use our hands and fingers. When you don’t have use of your hands (permanently or temporarily), there are limited alternatives. [Dorothee Clasen] has added one more option, [In]Brace, which is basically a small slide switch that you can operate with your tongue.

[In]Brace consists of a custom moulded retainer for the roof of your mouth, on which is a small ball with an embedded magnet, that slides long wire tracks. Above the track is a set of three magnetic sensors, that can detect the position of the ball. On the prototype, a wire from the three sensors run out of the corner of the users mouth, to a wireless microcontroller (Which looks to us like a ESP8266) hooked behind the user’s ear. In a final product, it would obviously be preferable if everything were sealed in the retainer. We think there is even more potential if one of the many 3-axis hall effect sensors are used, with a small joystick of rolling ball. The device could be used by disabled persons, for physical therapy, or just for cases where a person’s hands are otherwise occupied. [Dorothy] created a simple demonstration, where she plays Pong, or Tong in this case, using only the [In]Brace. Hygiene and making sure that it doesn’t somehow become a choke hazard will be very important if this ever became a product, but we think there is some potential.

[Kristina Panos] did a very interesting deep dive into the tongue as an HMI device a while ago, so this isn’t a new idea, but the actual implementations differ quite a lot. Apparently it’s also possible to use your ear muscles as an interface!

Thanks for the tip [Itay]!