Circuit Boards You Can Stretch: Liquid Metal Nanomaterials Make A Strange Flex

November 19, 2020 by Dan Maloney 9 Comments

If you think polyimide-based flexible PCBs are cool, wait until you get a load of what polymerized liquid metal networks can do.

Seems like [CNLohr] has some pretty cool friends, and he recently spent some time with a couple of them who are working with poly LMNs and finding out what they’re good for. Poly LMNs use a liquid metal composed of indium and gallium that can be sprayed onto a substrate through a laser-cut stencil. This results in traces that show the opposite of expected behavior; where most conductors increase in resistance when stretched, pol LMNs stay just as conductive no matter how much they’re stretched.

The video below shows [CNLohr]’s experiments with the stuff. He brought a couple of traditional PCB-based MCU circuits, which interface easily with the poly LMN traces on a thick tape substrate. Once activated by stretching, which forms the networks between the liquid metal globules, the traces act much like copper traces. Attaching SMD components is as simple as sticking them to the tape — no soldering required. The circuits remain impressively stretchy without any apparent effect on their electrical properties — a characteristic that should prove interesting for wearables circuits, biological sensors, and a host of real-world applications.

While poly LMNs aren’t exactly ready for the market yet, they don’t seem terribly difficult to make, requiring little in the way of exotic materials or specialized lab equipment. We’d love to see someone like [Ben Krasnow] pick this up and run with it — it seems right up his alley.

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Laser-Induced Graphene Supercapacitors From Kapton Tape

November 11, 2020 by Dan Maloney 47 Comments

From the sound of reports in the press, graphene is the miracle material that will cure all the world’s ills. It’ll make batteries better, supercharge solar panels, and revolutionize medicine. While a lot of applications for the carbon monolayer are actually out in the market already, there’s still a long way to go before the stuff is in everything, partly because graphene can be very difficult to make.

It doesn’t necessarily have to be so hard, though, as [Zachary Tong] shows us with his laser-induced graphene supercapacitors. His production method couldn’t be simpler, and chances are good you’ve got everything you need to replicate the method in your shop right now. All it takes is a 405-nm laser, a 3D-printer or CNC router, and a roll of Kapton tape. As [Zach] explains, the laser energy converts the polyimide film used as the base material of Kapton into a sort of graphene foam. This foam doesn’t have all the usual properties of monolayer graphene, but it has interesting properties of its own, like extremely high surface area and moderate conductivity.

To make his supercaps, [Zach] stuck some Kapton tape to glass slides and etched a pattern into with the laser. His pattern has closely spaced interdigitated electrodes, which when covered with a weak sulfuric acid electrolyte shows remarkably high capacitance. He played with different patterns and configurations, including stacking tape up into layers, and came up with some pretty big capacitors. As a side project, he used the same method to produce a remarkable effective Kapton-tape heating element, which could have tons of applications.

Here’s hoping that [Zach]’s quick and easy graphene method inspires further experimentation. To get you started, check out our deep-dive into Kapton and how not every miracle material lives up to its promise.

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Spider Silk, Spider Silk, Made Using A Strain Of Yeast

November 6, 2020 by Brian McEvoy 25 Comments

Companies spend thousands developing a project for the market, hoping their investment will return big. Investing like this happens every day and won’t shock anyone. What may surprise you is someone who spends more than a decade and thousands of their own dollars to make an open-source version of a highly-marketable product. In this case, we’re talking about genetically modified yeast that produces spider silk. If that sounds like a lead-in to some Spiderman jokes and sci-fi references, you are correct on both accounts. [Justin Atkin] had some geneticist work under his belt when he started, so he planned to follow familiar procedures like extracting black widow DNA, isolating and copying the silk genes, and pasting them into a yeast strain. Easy peasy, right? Naturally, good science doesn’t happen overnight.

There are a few contenders for the strongest spider silk among which the golden silk orb-weaver gets the most attention, but the black widow’s webbing is nearly as strong, and [Justin] is happy to wear black widow inspired bling, whereas the golden orb-weaver looks like it crawled out of Starship Troopers. His first attempt to extract DNA starts with a vial of preserved ~~nightmare fuel~~ spider specimens because that is a thing you can just go online and buy. Sadly, they were candied in alcohol, and that obliterates DNA, so he moved to dried specimens from breeders, which also failed to produce results, and those were just the landmark hangups.

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The Potatoes Of DOOM

October 13, 2020 by Matthew Carlson 25 Comments

Over the years, the 1993 classic Doom has gained an almost meme-like status where it can seemingly run on anything. Everything from printers to smartwatches has been shown off running the now-iconic first level of Doom. Looking to up the bar, [Equalo] set out to run Doom on potatoes. However until we develop full biological computers, he had to settle for running Doom on a device powered by potatoes. (Video, embedded below.)

As we’ve seen with other hacks before, potatoes are a decent power source that just requires potato, zinc, and copper. Some have attempted to make it easier to scale potato power and others have focused on making the individual potatoes more powerful. The biggest obstacle when working with potatoes as a battery is that even though each potato can put out almost a volt, the current is laughably small.

The lack of current is what drove [Equalo] to dramatically scale up the typical potato battery. With a target device of a Raspberry Pi Zero requiring around 100 mA at 4.5V, this means he needed over 700 potato slices. After boiling hundreds of potatoes and with a bit of help from friends and family, the giant potato battery was constructed, and we can’t help but marvel at the sheer scale and audacity. The challenge of scaling up a potato battery is that by the time you’re wiring up the 400th potato, your first potato has already started to corrode.

Next time you’re looking for some inspiration for a monumental task, perhaps watch the tale of [Equalo’s] giant potato battery and remember what can be accomplished with some determination and a hundred pounds of spuds.

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Friendly Fiberglassing: Can Hide Glue Replace Epoxy?

September 11, 2020 by Brian McEvoy 40 Comments

Hide glue has been around for thousands of years, and some of it is holding wood pieces three thousand years after application. It is made from animal protein, so vegetarians may want to stick to the petroleum-based adhesives. [Surjan Singh] wanted to see if its longevity made it a contender with modern epoxy by casting a couple of fiberglass car parts with the competing glues. In short, it doesn’t hold up in this situation, but it is not without merit.

Musical instrument makers and antique restorers still buy and use hide glue, but you would never expose it to heat or moisture. To its credit, hide glue doesn’t require a ventilator. All you need is boiling water and a popsicle stick, and you are in business. [Surjan] writes his findings like a narrative rather than steps, so his adventures are a delight to read. He found that a car part made with fiberglass and epoxy will withstand the weather better than the alternative because heat and humidity will soften hide glue. His Saab 96 isn’t the right application, but since it is nearly as strong as epoxy once set, you could make other fabric shapes, like a flannel nightstand or a lace coffee table, and you could shape them in the living room without toxifying yourself

No matter how you want to work with glues and substrates, Bil Herd has you covered, and here is an excellent tip for a cheap degassing setup.

3D-Printed Thermite Brings The Heat, And The Safety

September 10, 2020 by Kristina Panos 15 Comments

Thermites are a double-edged sword. Packing a tremendous energy density, and eager to produce tremendous heat when ignited, thermite is great for welding train tracks. But sometimes you might be looking for a little more finesse. A new approach to 3D printing thermites might just be able to tame the beast.

Most of us do our soldering while sitting safely indoors in a comfortable climate. The biggest dangers we’re likely to face are burnt fingertips, forgetting the heat shrink, or accidentally releasing the smoke monster. But outside of our homes and workshops, there’s a lot of extreme joining of metals going on. No matter where it’s done, welding and brazing in the field requires a lot of equipment, some of which is unwieldy and even more difficult to move around in harsh conditions.

Welding railroad tracks with thermite. Image via YouTube

The utility of brazing is limited by all the complex scaffolding of hardware required to support it. This limiting factor and the discovery of thermite led to exothermic welding, which uses an energetic material to provide enough heat to melt a filler metal and join the pieces. Energetic materials can store a lot of chemical energy and forcefully release it in a short period of time.

Thermites are made of metal oxide and metal powder, often iron oxide and aluminium. When ignited by a source of high heat, thermite compounds undergo an exothermic reduction-oxidation (redox) reaction as the aluminium reduces the number of electrons in the iron oxide atoms. More heat makes the reaction run faster, generating more heat, and so on. The result is molten iron and aluminium oxide slag.

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A 3D Printed Magnetic Stirrer For Your DIY Chemistry Projects

September 3, 2020 by Lewin Day 20 Comments

When mixing or agitating delicate solutions in the chemistry lab, a magnetic stirrer is often the tool of choice. They’re able to be easily sterilized and cleaned, while maintaining isolation between the mechanical parts and the solutions in question. While they can be purchased off the shelf, [Max Siebenschläfer] whipped up a design that can easily be built at home.

The build consists of a 3D printed base, containing a simple brushed motor. This is hooked up to a motor controller fitted with a simple potentiometer for adjusting the speed of rotation. The motor is then fitted with a small 3D printed spinner containing two magnets. A similar 3D printed part acts as a stirrer, and is fitted with a matching pair of magnets, and dropped into the solution. The magnets in the stirrer are attracted to the ones on the end of the motor, and so when the motor spins, the stirrer spins in the solution, with no physical contact required.

It’s a simple way to build a magnetic stirrer at home without having to shell out big money for a laboratory grade unit. We imagine this could be put to fun use for stirring coffee or cocktails, too – if built with a food-grade spinner. More advanced designs are also possible for the eager home scientist. Video after the break.

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