Enzymes Make Electricity From Thin Air

March 11, 2023 by Al Williams 17 Comments

There’s an old magic trick known as the miser’s dream, where the magician appears to pull coins from thin air. Australian scientists say they can now generate electricity out of thin air with the help of some enzymes. The enzyme reacts to hydrogen in the atmosphere to generate a current.

They learned the trick from bacteria which are known to use hydrogen for fuel in inhospitable environments like Antarctica or in volcanic craters. Scientists knew hydrogen was involved but didn’t know how it worked until now.

The enzyme is very efficient and can even work on trace amounts of hydrogen. The enzyme can survive freezing and temperature up to 80 °C (176 °F). The paper seems more intent on the physical mechanisms involved, but you can tell the current generated is minuscule. We don’t expect to see air-powered cell phones anytime soon. Then again, you have to start somewhere, and who knows where this could lead?

Microbial fuel cells aren’t new, of course. If you just want lights, you can skip the electricity altogether.

Making Dry Ice At Home Is Just As Hard As It Sounds

March 10, 2023 by Maya Posch 25 Comments

Along the road to developing his own cryocooler to produce liquid nitrogen, there are a number of interesting rabbit holes [Hyperspace Pirate] has found himself taking a look at. For example, using dry ice for a pre-cooling stage and subsequently wondering what it’d take to make this dry ice oneself.

Getting the CO₂ required for the dry ice is the easy part, requiring nothing more complicated than baking soda and a suitable acid (like hydrochloric acid). The other options to gather CO₂ include using yeast, capturing the gas from the air people breathe out, calcium hydroxide, etc., none of which are as easy or convenient.

The acid is mixed with the baking soda, with the produced gas led through a bubbler and subsequent dehumidification stage before being collected. For the more involved part of getting dry ice, a bit more science is needed. First, a compressor is used to get pressurized CO₂ into a previously evacuated tank at 160 psi (~12 bar). For the next phase the compressed gas has to be compressed further so that it condenses into a liquid. This involves a second compressor stage and a repurposed paintball tank. At the needed pressure of 1000 psi (69 bar), safety is essential.

With liquid carbon dioxide in the paintball tank, all it takes at this point is to turn the tank upside-down to get the liquid part near the exhaust valve and crank it open. Capturing the dry ice at this point is another fascinating challenge, which was partially solved by a 3D printed mold, with plenty of room for improvement still.

Given the cost and effort involved in producing it, just buying dry ice at the local store looks like it’s still the way to go for your Halloween fog machine this year. But it’s a fascinating experiment regardless, especially since it actually produced results — unlike some of the attempts we’ve covered previously.

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Supercon 2022: Alec Vercruysse Can See Through Murky Water

March 8, 2023 by Maya Posch 4 Comments

Detecting objects underwater isn’t an easy challenge, especially when things get murky and dark. Radio waves don’t propagate well, so most techniques rely on sound. Sonar is itself farily simple, simply send out a ping and listen for an echo, and that will tell you how far something is. Imaging underwater is significantly harder, because you would additionally need to know where each echo is coming from.

To answer the question of whether it is possible to put together an ultrasonic 3D imager that would cheaply enable anyone to image objects underwater, [Alec Vercruysse] and fellow team members at the Harvey Mudd College set out to create a system that does exactly that. You can read the presentation slides (PDF) or check out the entire project in the GitHub repository.

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Displaying The Time Is Elemental With This Periodic Table Clock

March 7, 2023 by Dan Maloney 8 Comments

We see a lot of clocks here at Hackaday, so many now that it’s hard to surprise us. After all, there are only so many ways to divide the day into intervals, as well as a finite supply of geeky and quirky ways to display the results, right?

That’s why this periodic table clock really caught our eye. [gocivici]’s idea is a simple one: light up three different elements with three different colors for hours, minutes, and seconds, and read off the time using the atomic number of the elements. So, if it’s 13:03:23, that would light up aluminum in blue, lithium in green, and vanadium in red. The periodic table was designed in Adobe Illustrator and UV printed on a sheet of translucent plastic by an advertising company that specializes in such things, but we’d imagine other methods could be used. The display is backed by light guides and a baseplate to hold the WS2812D addressable LEDs, and a DS1307 RTC module gives the Arduino Nano a sense of time. The 3D printed frame of the clock has buttons for setting the time and controlling the clock; the brief video below shows it going through its paces.

We really like the attention to detail [gocivici] showed here; that UV printing really gave some great results. And what’s not to like about the geekiness of this clock? Sure, it may not be as action-packed as a game of periodic table Battleship, but it would make a great conversation starter.

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What Does An Electron Look Like?

March 6, 2023 by Al Williams 23 Comments

In school, you probably learned that an atom was like a little solar system with the nucleus as the sun and electrons as the planets. The problem is, as [The Action Lab] points out, the math tells us that if this simplistic model was accurate, matter would be volatile. According to the video you can see below, the right way to think about it is as a standing wave.

What does that mean? The video shows a very interesting demonstrator that shows how that works. You can actually see the standing waves in a metal ring. This is an analog — still not perfect — for the workings of an atom. An input frequency causes the ring to vibrate, and at specific vibration frequencies, a standing wave develops in the ring.

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Graphene And Copper Nanowire Thermal Interface With Low Thermal Resistance

March 5, 2023 by Maya Posch 8 Comments

With the increasing waste heat production by today’s electronics in ever smaller spaces, drawing this heat away quickly enough to prevent thermal throttling or damage is a major concern. This is where research by Lin Jing and colleagues from Carnegie Mellon University’s Department of Mechanical Engineering demonstrates a thermal interface material (TIM) that should provide a significant boost here. In the article, published in ACS Nano (paywalled; open access preprint alternative) the construction of this copper and graphene ‘sandwich’ TIM is described, along with tests.

The general idea is to use pillars between the two surfaces that can quickly carry the heat from the hot surface to the cool one. Although pure copper versions exist and do work, they suffer from the complications of having to build up these copper pillars in place, and subsequent oxidation reducing the effectiveness. While graphene and similar materials have shown superior heat-transfer capabilities, interfacing these materials with copper and other metals has proven problematic.

What Lin Jing et al. demonstrate in this study is to use essentially the pure copper approach, but to combine it with earlier research by Raghav Garg et al. (2017), who demonstrated how to grow 3-dimensional graphene structures. By cladding the copper pillars with graphene, this material improves heat transfer by 60%, while preventing oxidation of the metal. While the challenge is obviously to transfer these findings to something that can be mass-produced for consumer devices, it demonstrates how much potential there is in the use of graphene, which is a relatively new material for such applications due to how hard it was to produce until recently.

Compact Ultrasonic Holographs For Single Step Assembly Of Matter In 3D

February 27, 2023 by Maya Posch 7 Comments

Creating three-dimensional shapes from basic elements or even cells is an important research topic, with potentially many applications in the fields of medicine and general research. Although physical molds and scaffolding can be used, the use of ultrasonic holographs is in many ways preferable. Using ultrasonic sound waves into a liquid from two or more transducers shaped to interact in a predetermined manner, any particulates suspended in this liquid will be pushed into and remain in a specific location. Recent research by [Kai Melde] and colleagues has produced some fascinating results here, achieving recognizable 3D shapes in a liquid medium.

These are some of the most concrete results produced, following years of research. What distinguishes ultrasonic holography from light-based xolography is that the latter uses photon interference between two light sources in order to rapidly 3D print an object within the print medium, whereas ultrasonic holography acts more as a ultrasonic pressure-based mold. Here xolography is also more limited in its applications, whereas ultrasonic holography can be used with for example biological tissue engineering, due to the gentle pressure exerted on the suspended matter.

For ongoing medical research such as the growing of organs (e.g. for transplantation purposes), scaffolding is required, which could be assembled using such a technique, as well as the manipulation and assembly of biological tissues directly.