Is That A Triboelectric Generator In Your Shoe?

The triboelectric effect is familiar to anyone who has rubbed wool on a PVC pipe, or a balloon on a childs’ hair and then stuck it on the wall. Rubbing transfers some electrons from one material to the other, and they become oppositely charged. We usually think of this as “static” electricity because we don’t connect the two sides up with electrodes and wires. But what if you did? You’d have a triboelectric generator.

In this video, [Cayrex] demonstrates just how easy making a triboelectric generator can be. He takes pieces of aluminum tape, sticks them to paper, and covers them in either Kapton or what looks like normal polypropylene packing tape. And that’s it. You just have to push the two sheets together and apart, transferring a few electrons with each cycle, and you’ve got a tiny generator.

As [Cayrex] demonstrates, you can get spikes in the 4 V – 6 V range with two credit-card sized electrodes and fairly vigorous poking. But bear in mind that current is in the microamps. Given that, we were suprised to see that he was actually able to blink an LED, even if super faintly. We’re not sure if this is a testament to the generator or the incredible efficiency of the LED, but we’re nonetheless impressed.

Since around 2012, research into triboelectric nanogenerators has heated up, as our devices use less and less power and the structures to harvest these tiny amounts of power get more and more sophisticated. One of the coolest such electron harvesters is 3D printable, but in terms of simplicity, it’s absolutely hard to beat some pieces of metal and plastic tape shoved into your shoe.

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A Look At 3D Printed Shoes: Hybrid, Fully Printed And Plain Weird

In the eternal quest to find more things to do with 3D printers, shoes have been in the spotlight for a while now. But how practical is additive manufacturing in this field really?

Adidas Ultra 4D running shoes with 3D printed midsole.
Adidas Ultra 4D running shoes with 3D printed midsole.

This is where [Joel Telling] of the 3D Printing Nerd YouTube channel puts in his two cents, with a look at a range of commercial and hobbyist ideas and products. Naturally, the first thing that likely comes to mind at the words ‘3D printed shoes’ is something akin to the plastic version of wooden clogs, or a more plastic-y version of the closed-cell resin of Crocs.

First on the list are the white & spiky Kaiju Gojira shoes from Fused Footwear, printed from TPE filament to order. TPE is softer to the touch and more flexible than TPU, but less durable. In contrast the Adidas Ultra 4D running shoes (from their 4D range) are a hybrid solution, with a standard rubber outsole, 3D printed midsole with complex structures and mostly fabric top part. Effectively a Nike Air in initial impression, perhaps.

Meanwhile ‘3D printed’ shoes ordered off Chinese store Shein turned out to be not 3D printed at all, while [Joel] seems to be really into fully 3D printed shoes from Zellerfeld, who appear to be using TPU. While it’s hard to argue about taste, the Adidas shoes might appeal to most people. Especially since they’d likely let your feet breathe much better, a fact appreciated not only by yourself, but also family members, roommates and significant others. So which of these (partially) 3D printed shoes would you pick, or do you have some other favorite?

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Combadge Project Wants To Bring Trek Tech To Life

While there’s still something undeniably cool about the flip-open communicators used in the original Star Trek, the fact is, they don’t really look all that futuristic compared to modern mobile phones. But the upgraded “combadges” used in Star Trek: The Next Generation and its various large and small screen spin-offs — now that’s a tech we’re still trying to catch up to.

As it turns out, it might not be as far away as we thought. A company called Vocera actually put out a few models of WiFi “Communication Badges” in the early 2000s that were intended for hospital use, which these days can be had on eBay for as little as $25 USD. Unfortunately, they’re basically worthless without a proprietary back-end system. Or at least, that was the case before the Combadge project got involved.

Designed for folks who really want to start each conversation with a brisk tap on the chest, the primary project of Combadge is the Spin Doctor server, which is a drop-in replacement for the original software that controlled the Vocera badges. Or at least, that’s the goal. Right now not everything is working, but it’s at the point where you can connect multiple badges to a server, assign them users, and make calls between them.

It also features some early speech recognition capabilities, with transcriptions being generated for the voices picked up on each badge. Long-term, one of the goals is to be able to plug the output of this server into your home automation system. So you could tap your chest and ask the computer to turn on the front porch light, or as the documentation hopefully prophesies, start the coffee maker.

There hasn’t been much activity on the project in the last year or so, but perhaps that’s just because the right group of rabid nerds dedicated developers has yet to come onboard. Maybe the Hackaday community could lend a hand? After all, we know how much you like talking to your electronics. The hardware is cheap and the source is open, what more could you ask for?

Dev Board Watch Takes Path Of Least Resistance

Building your own watch or clock is kind of a maker’s rite of passage. Once upon a time, if you went with a wrist watch, you’d typically work on producing your own compact PCB with everything crammed into a typical watch form factor, maybe relying on a simple binary output for compactness and simplicity. Times have changed, however, and [Arnov]’s design is altogether different in its construction.

The build relies on a XIAO ESP32-C3 microcontroller board as the brains of the operation. It’s paired with the XIAO expansion board. It’s designed as a carrier for the ESP32-C3, giving it a bunch of IO that’s accessible over readily-accessible connectors. It also features a display, a real-time clock, and a battery — pretty much the three main things you’d need to add to an ESP32 to turn it into a watch.

Thus, with the electronics pretty much done, it was simply up to [Arnov] to turn the device into a watch. He achieved this by screwing the frame and strap of an old Casio watch to a 3D printed carrier for the XIAO expansion board. With that done, it was simply a matter of writing the code to show the time from the RTC on the display. There’s no connectivity features, no smart stuff going on — just the time and date for your perusal.

Some might decry the project for simply slapping a watch band on a devboard. Or, you could look at how this indicates just how fast and easy development can be these days. Once upon a time, you could spend weeks trying to find a cheap display and then further weeks trying to get it working with your microcontroller. Now you can spend $20, get the parts in a few days, and get your project blasting along minutes later.

If you’ve done an altogether more ornate watch build of your own, we’d love to see that, too. Show us on the tipsline!

A Solar-Powered Wristwatch With An ATtiny13

Wristwatches come in many shapes, sizes, and types, but most still have at least one thing in common: they feature a battery that needs to be swapped or recharged somewhere been every other day and every few years. A rare few integrate a solar panel that keeps the internal battery at least somewhat topped up, as environmental light permits.

This “Perpetual” wristwatch designed by [Serhii Trush] aims to keep digitally ticking along using nothing but the integrated photodiodes, a rechargeable LIR2430 cell, and a power-sipping face that uses one LED for each hour of the day.

The face of the perpetual wristwatch. (Credit: Serhii Trush)
The face of the perpetual wristwatch. (Credit: Serhii Trush)

The wristwatch’s operation is demonstrated in the linked video (in Ukrainian, auto-generated subtitles available): to read out the current time, the button in the center is pressed, which first shows the hour, then the minutes (in 5 minute intervals).

After this the ATtiny13 MCU goes back to sleep, briefly waking up every 0.5 seconds to update the time, which explains why there’s no RTC crystal. The 12 BPW34S photodiodes are enough to provide 2 mA at 0.5 V in full sunlight, which together keep the LIR2430 cell charged via a Zener diode.

As far as minimalistic yet practical designs go, this one is pretty hard to beat. If you wish to make your own, all of the design files and firmware are provided on the GitHub page.

Although we certainly do like the exposed components, it would be interesting to see this technique paired with the PCB watch face we covered recently.

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A dress is shown in three shapes: the original, a slightly-heated A-line version, and a close-fitting body con version.

4D Knit Dress Skirts Waste

Regular 2D sewing of anything is inherently wasteful. You can align the pattern pieces however you want, but there’s going to be wasted everything — thread, fabric, and interfacing — whether you get it right the first time or not. Never mind the fact that people tend to create a muslin (prototype) first using inexpensive fabric (like muslin) for the purposes of getting the fit right.

A few examples of the lines than can be created.

The MIT Self-Assembly Lab x Ministry of Supply have come up with a 4D garment construction technique that minimizes waste while being pretty darn cool at the same time. They’ve created a knit dress that combines several techniques and tools, including heat-activated yarns, computerized knitting, and 6-axis robotic activation. The result is a dress that can be permanently molded to fit the body however and wherever you want, using a heat gun mounted on a 6-axis robotic arm.

As far as we can tell, a finished dress does not come off of the machine in the short demo video after the break. It looks like it still has to be sewn together, which creates some potential for waste, but absolutely nothing like conventional methods.

This is probably the coolest dress we’ve seen since the one covered in LCD panels.

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LED Choker Is A Diamond In The Junk Pile

Isn’t it great when you find a use for something that didn’t work out for the project it was supposed to? That’s the story behind the LED strips in this lovely blinkenlights choker by [Ted].

The choker itself is a 15 mm wide leather strap with holes punched in it. According to [Ted], the hole punching sounds like the absolute worst and hardest part to do, because the spacing of the holes must be greater than that of the LEDs to account for flex in the strap. [Ted] tested several distances and found that there is little margin for error.

Controlling those blinkenlights is a Seeed Xiao S3, which fits nicely behind the neck in what looks like a heat shrink tube cocoon. [Ted] chose this because there was one lying around, and it happens to be a good fit with its LiPo charge controller.

The choker runs on four 300 mAh LiPo batteries, which makes for more bulk than [Ted] would like, but again, sometimes it’s about what you have lying around. Even so, the batteries last around two hours.

Sometimes it’s about more than just blinkenlights. Here’s an LED necklace that reports on local air quality.