Stretchable Traces for Flexible Circuits

Electronic components are getting smaller and smaller, but the printed circuit boards we usually mount them on haven’t changed much. Stiff glass-epoxy boards can be a limiting factor in designing for environments where flexibility is a requirement, but a new elastic substrate with stretchable conductive traces might be a game changer for wearable and even implantable circuits.

qxMo1DResearchers at the Center for Neuroprosthetics at the École Polytechnique Fédérale de Lausanne are in the business of engineering the interface between electronics and the human nervous system, and so have to overcome the mismatch between the hardware and wetware. To that end, [Prof. Dr. Stéphanie P. Lacour]’s lab has developed a way to apply a liquid metal to polymer substrates, with the resulting traces capable of stretching up to four times in length without cracking or breaking. They describe the metal as a partially liquid and partially solid alloy of gallium, with a gold added to prevent the alloy from beading up on the substrate. The applications are endless – wearable circuits, sensors, implantable electrostimulation, even microactuators.

Looks like progress with flexibles is starting to pick up, what with the conductive silicone and flexible phototransistors we’ve covered recently. We’re excited to see where work like this leads.

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Blinky LED Bike Bag

Bicycle riders can never be too visible: the more visible you are, the less chance there is someone will hit you. That’s the idea behind the Arduibag, a neat open-source project from [Michaël D’Auria] and [Stéphane De Graeve]. The project combines a joystick that mounts on the handlebars with a dot matrix LED display in a backpack. By moving the joystick, the user can indicate things such as that they are turning, stopping, say thank you or show a hazard triangle to warn of an accident.

The whole project is built from simple components, such as an Adafruit LED matrix and a Bluno (an Arduino-compatible board with built-in Bluetooth 4.0) combined with a big battery that drives the LED matrix. This connects to the joystick, which is in a 3D printed case that clips onto the handlebars for easy use. It looks like a fairly simple build, with the larger components being mounted on a board that fits into the backpack and holds everything in place. You then add a clear plastic cover to part of the backpack over the LED matrix, and you are ready to hit the road, hopefully without actually hitting the road.

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Mechatronic Cat Ears For The Rest Of Us

Every now and then you see a project that makes you smile. It may not be something that will deliver world peace or feed the hungry, but when it opens in your browser in the morning you go to work a bit happier for the experience.

Just such a project is [Radomir Dopieralski’s] set of wearable mechatronic cat ears. A cosplay accessory that moves as you do. Very kawaii, but fun.

You may have seen the commercially available Necomimi brainwave activated mechatronic ears. [Radomir’s] version does not share their sophistication, instead he’s using an accelerometer to detect head movement coupled to an Arduino Pro Mini driving a pari of servos which manipulate the ears. He provides the source code, and has plans for a miniaturised version using an ATtiny85 on its own PCB.

Amusing cuteness aside, there are some considerations [Radomir] has had to observe that apply to any a head-mounted wearable computer. Not least the problem of putting the Pro Mini and its battery somewhere a little more unobtrusive and weatherproof than on top of his head. He also found that the micro-servos he was using did not have enough range of movement to fully bend the ears, something he is likely to address in a future version with bigger servos. He’s yet to address a particularly thorny problem: that a pair of servos mounted on your head can be rather noisy.

We’ve covered quite a few cosplay stories over the years. This is not even our first cat ear story. More than one example of a Pip Boy, a HAL 9000 costume, and a beautifully made Wheatley puppet have made these pages, to name a few. So scroll down and enjoy [Radomir’s] video demonstration of the ears in action.

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Ski Buddy Jacket Uses Arduino to Teach Youngsters to Ski

Snow skiing looks easy, right? You just stay standing, and gravity does the work. The reality is that skiing is difficult for beginners to learn. [19mkarpawich] loves to ski, but he was frustrated seeing crying kids on skis along with screaming parents trying to coach them. Inspired by wearable electronics, he took an Arduino, an old jacket, some LEDs, and created Ski Buddy.

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Smart Sweatbands

If you’ve ever known anyone who has to monitor their blood glucose level, you know it is annoying to have to prick your finger with a lancet to draw blood for each measurement. A new sweatband that incorporates flexible electronics can measure glucose–as well as sodium, potassium, and lactate–from your sweat, without a painful pin prick.

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ATtiny Watch is Tiny

[陳亮] (Chen Liang) is in the middle of building the ultimate ring watch. This thing is way cooler than the cheap stretchy one I had in the early 1990s–it’s digital, see-through, and it probably won’t turn [陳]’s finger green.

watch-gutsThe current iteration is complete and builds upon his previous Arduino-driven watch building experiences. It runs on an ATtiny85 and displays the time, temperature, and battery status on an OLED. While this is a fairly a simple build on paper, it’s the Lilliputian implementation that makes it fantastic.

[陳] had to of course account for building along a continuous curve, which means that the modules of the watch must be on separate boards. They sit between the screw bosses of the horseshoe-shaped 3D-printed watch body, connected together with magnet wire. [陳] even rolled his own coin cell battery terminals by cutting and doubling over the thin metal bus from a length of bare DuPont connector.

If you’re into open source watches but prefer to wear them on your wrist, check out this PIC32 smart watch or the Microduino-based OSWatch.

Remote-Controlled Eyebrows for Your Birthday

We’re not sure that [Alec]’s dad actually requested remote-controlled eyebrows for his birthday, but it looks like it’s what he got! As [Alec] points out, his father does have very expressive eyebrows, and who knows, he could be tired of raising and lowering them by himself. So maybe this is a good thing? But to us, it still looks a tiny bit Clockwork Orange. But we’re not here to pass judgement or discuss matters of free will. On to the project. (And the video, below the break.)

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An ATmega328 (otherwise known as cheap Cloneduino Alec wrote that the 328 was from a real Arduino) is trained to run motors in response to IR signals. An L293D and a couple of gear motors take care of the rest. Sewing bobbins and thread connect the motors to the eyebrows. And while it’s not entirely visible in the photo, and veers back into not-sure-we’d-do-this-at-home, a toothpick serves as an anchor for the thread and tape, secured just underneath the ‘brows for maximum traction.

We have to say, we initially thought it was going to be a high-voltage muscle-control hack, and we were relieved that it wasn’t.

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