Give Me A Minute, My Eyes Are Busy

September 11, 2020 by Brian McEvoy 3 Comments

Social cues are tricky, but humans are very good at detecting where someone is looking; that goes a long way toward figuring out where someone is placing their attention. All of this goes right out the window though, when you’re talking with somebody who uses eye-tracking software to speak. [Matthew Oppenheim] with Lancaster University, UK wants to give listeners the message of Give Me a Minute with an easy-to-recognize indicator. His choice is a microBit, which displays a rotating arrow on the LED array while someone composes their speech. He chose the microBit because they are readily available, and you can get cases to fit people’s personalities. After the break, you can see a demonstration, but the graphic appears scrambled because of the screen flicker. The rotating arrow is a clear indicator that someone is writing, whereas a clock might suggest a frozen computer, and a progress bar could not be accurate.

[Matthew] wrote a program for the interpreting computer which recognizes when a message is forming by monitoring the number of black pixels in the composition field. If it changes, someone must be composing a sentence. Many people will try to peek over the speaker’s shoulder and see if they are working, but we’re sure that most readers would join the users of such tech in being unhappy if someone blatantly looks at theirr computer screen while they are typing.

Wheelchairs don’t always have to come from a hospital or supply store, and they don’t have to stay on the ground.

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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 Orlando Hoilett 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.

Cerebral Palsy Tool Assistant

September 3, 2020 by Brian McEvoy 2 Comments

We all deserve to create. Some people seem to have the muses hidden in their pocket, but everyone benefits when they express themselves in their chose art form. Each of us has tools, from Dremels to paintbrushes, and many folks here build their own implements. Even if we don’t have our macro-enabled mechanical keyboard or a dual-extrusion printer, we can make due. But what if you couldn’t operate your drill, or mouse, or even a pencil? To us, that would be excruciating and is the reality for some. [Laura Roth] and [Christopher Sweeney] are art teachers designing a tool holder for their students with cerebral palsy so that they can express themselves independently.

On either side of this banner image, you can see pencil drawings from [Sara], who has spastic cerebral palsy. She made these drawings while wearing the tool holder modeled after her hand. Now, that design serves other students and is part of the 2020 Hackaday Prize. The tool holder wraps around the wrist like a wide bracelet. Ribbing keeps its shape, and a tube accepts cylindrical objects, like pencils, styluses, and paintbrushes.The result is that the tip of the pencil is not far from where it would have been if held in the hand, but this sidesteps issues with grip and fine control in hands and fingers.

The print is available as an STL and should be printed with flexible filament to ensure it’s comfortable to wear. Be mindful of digital styluses which may need something conductive between the barrel and user.

Hackers are familiar with the challenges of cerebral palsy, and we’ve enjoyed seeing a variety of solutions over the years like door openers, camera gimbals, and just being altogether supportive.

Fog-Free Mask Hack Solves Mask Versus Glasses Conundrum With Superb Seal

September 2, 2020 by Brian McEvoy 35 Comments

If you have worn a mask and glasses together for more than a quarter of a second, you are probably annoyed that we don’t have a magical solution for foggy lenses. Moisture-laden air is also a good indicator of where unfiltered air is escaping. Most masks have some flexible metal across the nose bridge that is supposed to seal the top, but it is woefully inadequate. The Badger Seal by [David Rothamer] and [Scott Sanders] from the University of Wisconsin-Madison College of Engineering is free to copy during the COVID-19 pandemic, even commercially. It works by running an elastic cord below the jaw and a formable wire over the nose to encourage contact all around both mouth and nose.

You can build your own in three ways. Each configuration is uniquely suited to a different situation. The first design is the easiest to make and should work for most people. The second is best for folks who need a better seal on the lower half of their face, like someone sporting a beard. It can also have ear loops, and that means your 3D printed ear savers have another use. The Madison campus of the University of Wisconsin also has fun with lock cracking and graphene experiments.
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Karting Hands-Free

September 1, 2020 by Brian McEvoy 3 Comments

Some of us have computer mice with more buttons than we have fingers, resolution tracking finer than a naked eye can discern, and forced-air vents. All these features presuppose one thing; the user has a functioning hand. [Federico Runco] knows that amyotrophic lateral sclerosis, ALS, or Lou Gehrig’s disease, will rob a person of their ability to use standard computer inputs, or the joystick on a motorized wheelchair. He is building EyesDrive for the 2020 Hackaday Prize, to restore that mobility to ALS patients. There are already some solutions, but this one focuses on a short bill of materials.

Existing systems are expensive and often track pupil location, which returns precise data, but EyesDrive only discerns, left, right, and resting. For these, we need three non-invasive electrodes, a custom circuit board with amplifiers, signal processing circuits, and a microcontroller. He includes a Bluetooth socket on the custom PCBs, which is the primary communication method. In the video below he steers a virtual kart around a knotty course to prove that his system is up to the task of an urban wheelchair.

EyesDrive by [Federico Runco] should not be confused with the HackadayPrize2015 winner, Eyedrivomatic, lead by two remarkable hackers, Steve Evans and Patrick Joyce.

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Read My Lips, Under This No-Sew Mask

August 30, 2020 by Brian McEvoy 5 Comments

Humans continuously communicate with our bodies, and face masks cover one of the most expressive parts. For some, this is a muffler on strangers, but devastating for people who rely on lip-reading. Several masks exist that have a clear window for precisely this purpose, but they’re specialty and high-demand. [Erin St Blaine] over at Adafruit shows how she makes windowed masks with stuff you may already have in your house. Even if your sewing machine is locked up the local maker-space, you are in luck, because you don’t need a single stitch. For the thread-inclined, it is easy to tweak the recipe.

The part of the mask that touches your face is terry cloth, but any breathable cotton towel should work. There is a PDF in the instructions where you can print templates in four sizes. You will also find a cutout for the plastic window salvaged from your cold soft drink cup. A water bottle should work too. Flexible glue holds the fabric together, but to attach the ear-loops, we fall back on our old friend, the red Swingline. If you don’t have that color and brand, any stapler will do in a pinch. Don’t forget to add some defogger and keep smiling.

Wear your homemade mask proudly and fasten it well, but not too fast.

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A New Spin On A Medical Test

August 28, 2020 by Brian McEvoy 5 Comments

Most of us can say that we have taken an obsolete hard drive out of a computer and felt it was a waste to toss it in the e-waste pile. Some of us have children’s drawings hung on the fridge with actuator magnets, or maybe a vast spreadsheet suspended on a steel filing cabinet. Let us not forget that there is also a high-speed, low-noise motor in there. On some models it is separate from the PCB, so grab an Electronic Speed Controller (ESC), your microcontroller of choice, and make yourself a salvaged HDD centrifuge like [Cave Man] has. His build uses the tray as a chassis, but he modeled and printed a new face in the same style as the original.

On top, he has an OLED screen for displaying the requested speed, measured speed, and runtime. Next to the display is a four-button pad with a customized legend for setting parameters. The video after the break shows the machine running through its paces. This version accommodates the tiny capillary tubes, microhematocrit tubes, for processing raw blood. This test can calculate the packed cell volume, which professionals use to determine things from dehydration to anemia.

There are other builds out there where people have modified an old drive into the kind of centrifuge that accepts larger diameter tubes, but this was a shining example of what is possible. One good turn deserves another, so we recommend a desktop bio-lab companion, or enlist some LEGO Mindstorms to help out.

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