New Transistor Uses Metal And Air Instead Of Semiconductors

December 3, 2018 by Al Williams 59 Comments

The more things change, the more things stay the same. Early electronic devices used a spark gap. These have been almost completely replaced with tubes and then semiconductor devices such as transistors. However, transistors will soon reach a theoretical limit on how small they can be which is causing researchers to find the next thing. If the Royal Melbourne Institute of Technology has its way, we’ll go back to something that has more in common with a spark gap than a conventional transistor. You can find the source paper on the Nano Papers website although the text is behind a paywall.

The transistor uses metal, but instead of a semiconductor channel — which is packed with atoms that cause collisions as electrons flow through the channel — the new device uses an air gap. You might well think that if fewer atoms in the channel are better, why not use a vacuum?

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Simple, Low-Cost Rig Lets The Budding Biohacker Run DNA Gels

December 1, 2018 by Dan Maloney 12 Comments

We all the know the basic components for building out an electronics lab: breadboards, bench power supply, a selection of components, a multimeter, and maybe an oscilloscope. But what exactly do you need when you’re setting up a biohacking lab?

That’s the question that [Justin] from The Thought Emporium is trying to answer with a series of videos where he does exactly that – build a molecular biology lab from scratch. In the current installment, [Justin] covers the basics of agarose gel electrophoresis, arguably the fundamental skill for aspiring bio-geeks. Electrophoresis is simply using an electric field to separate a population of macromolecules, like nucleic acids and proteins, based on their sizes. [Justin] covers the basics, from building a rig for running agarose gels to pouring the gels to doing the actual separation and documenting the results. Commercial grade gear for the job is priced to squeeze the most money out of a grant as possible, but his stuff is built on the cheap, from dollar-store drawer organizers and other odd bits. It all works, and it saves a ton of money that can be put into the things that make more sense to buy, like fluorescent DNA stain for visualizing the bands; we’re heartened to see that the potent carcinogen ethidium bromide that we used back in the day is no longer used for this.

We’re really intrigued with [Justin]’s bio lab buildout, and it inspires us to do the same here. This and other videos in the series, like his small incubators built on the cheap, will go a long way to helping others get into biohacking.

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72 Tranducers For Acoustic Levitation

November 28, 2018 by Zoe Skyforest 9 Comments

Levitation has a way of arousing curiousity and wonder wherever it appears. There’s a multitude of ways to do it, each with their own strengths and weaknesses and ideal use cases. [Julius Kramer] tried his hand at acoustic levitation, and decided to share his build.

The build relies on an astounding number of ultrasonic transducers – 72, in fact. The device operates at 40 kHz to be well above the human range of hearing. 36 each are placed in the top and bottom shells of the device’s 3D printed chassis. Through careful construction, the transducers are placed an integer multiple of half the wavelength apart. This allows the device to create a standing wave, with several low-energy nodes in which small objects can be levitated. In this case, [Julius] uses small scraps of styrofoam, but notes that water droplets can also be used if one is careful to avoid spilling any on the electronics.

The transducers are energised with a square wave generated by an Arduino Nano. This allows the possibility of the frequency and phase of the wave to be altered, which can help tune the device and allow some movement in the vertical axis. Unfortunately, movement in the other axes isn’t possible as the transducers appear to be connected in parallel. However, this could be a good upgrade in a later revision.

This project shows that a device relying on incredibly precise measurement and control can now be constructed at home with a 3D printer and some off the shelf electronics.

Now that you’ve whet your whistle, perhaps you’d like to tackle laser levitation?

[Thanks to Baldpower for the tip!]

Sci-Hub: Breaking Down The Paywalls

November 27, 2018 by Steven Dufresne 125 Comments

There’s a battle going on in academia between the scientific journal publishing companies that have long served as the main platform for peer review and spreading information, and scientists themselves who just want to share and have access to the work of their fellows. arxiv.org launched the first salvo, allowing researchers in physics to self-publish their own papers, and has gained some traction in mathematics and computer science. The Public Library of Science journals focus on biology and medicine and offer peer review services. There are many others, and even the big firms have been forced to recognize the importance of open science publication.

But for many, that’s still not enough. The high prestige journals, and most past works, are stuck behind paywalls. Since 2011, Sci-Hub has taken science publishing open by force, illegally obtaining papers and publishing them in violation of copyright, but at the same time facilitating scientific research and providing researchers in poorer countries with access that their rich-world colleagues take for granted. The big publishing firms naturally fought back in court and won, and with roughly $20 million of damages, drove Sci-Hub’s founder underground.

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The Metal That Never Forgets: Nitinol And Shape-Memory

November 23, 2018 by Mike Szczys 13 Comments

You’ve likely heard of Nitinol wire before, but we suspect the common base knowledge doesn’t go much beyond repeating that it’s a shape-memory alloy. [Bill Hammack], the Engineer Guy, takes us on a quick journey of all the cool stuff there is to know about Nitinol and shape-memory alloys.

The name itself is like saying Kleenex when you mean tissue, or using the V-word when you mean hook and loop fasteners. The first few letters of Nickel Titanium Naval Ordnance Laboratories combine to form the name of what is essentially a nickel-titanium alloy developed in 1962: Nitinol. It’s called shape-memory because you can stretch or bend it at room temperature and it will return to the original shape when heated at around 75 C (167 F). This particular metal can do that because its bonds form a “twinned structure” of rhombus shapes — bending or stretching moves those rhombuses (or rhombi, take your pick) but doesn’t change which atoms are bonded to one another.

Has this material science excursion bored you to tears yet? That’s why we love [Bill’s] work. He has always done a fantastic job of demystifying common mysticism and this is no different. The video below does a much better job of illustrating what we’ve described above, but also pull out a Nitinol engine for added wow-factor. A straight piece of Nitinol is bent into a loop around two pulleys. The lower pulley is submerged in hot water, causing the Nitinol to want to straighten out, but it loops back to the top pulley, bending and cooling in the air and creating a lever effect that drives the engine. We saw a more complex version of this concept last year.

You know those eyeglass frames you can bend in any way and they’ll pop back to the original shape? They’re taking advantage of the super-elasticity of Nitinol. [Bill] also recounts uses as stents for medical applications, and oddball engineering tricks in the automotive industry.

It’s great to see the Engineer Guy back. Favorites of ours have been the science behind disposable diapers and the aluminum beverage can. More recently he released Faraday’s lecture series, wrote a book on airships, appeared on Outlaw Tech on the Science Channel, and started a family. Thanks for fitting these illustrative videos in when you can [Bill]!

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The Kilogramme Will Cease To Be A Physical Entity

November 16, 2018 by Jenny List 72 Comments

One of the most illuminating high school courses no doubt for many readers as much as for your scribe, was the series of physics lessons during which the SI units were explained. That glorious sense of having the order of the universe unlocked into an interlocking series of units whose definitions could all be derived in terms of a series of base units was mind-blowing in those early teen years, and even though the explanations might have been at a for-the-children level that has been blown out of the water by later tiers of learning it’s still a bedrock that will serve an engineer or scientist life-long.

The definitions of the SI base units have evolved with scientific advancement to the point at which they are no longer tied to their original physical entity definitions. Of all the base units though there is still one that has resisted the urge to move away from the physical: the kilogramme (giving it its French spelling to preserve context) is still defined in terms of a metal cylinder in a laboratory just outside Paris. Kg diehards have not much time left to cling onto their platinum-iridium alloy though, for a new definition has been adopted in which it is derived from Planck’s Constant. From next May this will become the official kilogram, at which point concerns over microscopic erosion of the metal standard become irrelevant, and an SI kilogram can be replicated by any laboratory with the means to do so.

The piece of apparatus that makes this definition possible is the Kibble balance, a balance in which the force required to overcome the effect of gravitational force on a given mass is measured in terms of the electrical power required to do so. The gravitational force at a given point can be measured accurately and is defined in terms of the other SI units, while the electrical power can be derived from a Josephson junction, a superconducting junction whose current is defined in terms of Planck’s constant. As a result, the kilogram can be measured solely in terms of the constant and other SI units, consigning the metal cylinder to history.

This high-end metrology and physics make for interesting reading, but it’s fairly obvious that the de facto kilogram we all use will not change. Our everyday measures of everything from sugar to PLA filament will be the same today as they will be next May. But that’s not the point, everyday measurements do not need the extreme accuracy and reproducibility of a laboratory. The point of it all comes in as yet unforseen applications, as an example would the ability to synchronise timing to create GPS or digital radio have been possible were the second to be still defined in terms of astronomical movements rather than atomic states?

Standard kilogramme replica picture: Japs 88 [CC BY-SA 3.0]

Supercon: Designing Your Own Diffractive Optics

November 16, 2018 by Brian Benchoff 15 Comments

Kelly Peng is an electrical and optical engineer, and founder of Kura AR. She’s built a fusion reactor, a Raman spectrometer, a DIY structured light camera, a linear particle accelerator, and emotional classifiers for likes and dislikes. In short, we have someone who can do anything, and she came in to talk about one of the dark arts (pun obviously intended): optics.

The entire idea of Kura AR is to build an immersive augmented reality experience, and when it comes to AR glasses, there are two ways of doing it. You could go the Google Glass route and use a small OLED and lenses, but these displays aren’t very bright. Alternatively, you could use a diffractive waveguide, like the Hololens. This is a lot more difficult to manufacture, but the payoff will be a much larger field of view and a much more immersive experience.

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