Science

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Scanning electron micrograph of a microfabricated lens array

Getting A Fly’s-Eye View With Microfabricated Lens Arrays

September 7, 2021 by 11 Comments

Atomic force microscopy, laser ablation, and etching with a witches brew of toxic chemicals: sounds like [Zachary Tong] has been playing in the lab again, and this time he found a way to fabricate arrays of microscopic lenses as a result.

Like many of the best projects, [Zach]’s journey into micro-fabrication started with a happy accident. It happened while he was working on metal-activated chemical etching (MACE), which uses a noble metal catalyst to selectively carve high-aspect-ratio features in silicon. After blasting at a silver-coated silicon wafer with a laser, he noticed the ablation pits were very smooth and uniform after etching. This led him to several hypotheses about what was going on, all of which he was able to test.

The experiments themselves are pretty interesting, but what’s really cool is that [Zach] realized the smooth hemispherical pits in the silicon could act as a mold for an array of microscopic convex lenses. He was able to deposit a small amount of clear silicone resin into the mold by spin-coating, and (eventually) transfer the microlens array to a glass slide. The lenses are impressively small — hundreds of them over only a couple hundred square microns — and pretty well-formed. There’s always room for improvement, of course, but for an initial attempt based on a serendipitous finding, we’d call it a win. As for what good these lenses are, your guess is as good as ours. But novel processes like these tend to find a way to be useful, and the fact that this is coming out of a home lab doesn’t change that fact.

We find this kind of micro-fabrication fascinating. Whether it’s making OLED displays, micro-machining glass with plasma, or even rolling your own semiconductors, we can’t get enough of this stuff.

Continue reading “Getting A Fly’s-Eye View With Microfabricated Lens Arrays” →

Image of detonation engine firing

Japanese Rocket Engine Explodes: Continuously And On Purpose

September 2, 2021 by 62 Comments

Liquid-fuelled rocket engine design has largely followed a simple template since the development of the German V-2 rocket in the middle of World War 2. Propellant and oxidizer are mixed in a combustion chamber, creating a mixture of hot gases at high pressure that very much wish to leave out the back of the rocket, generating thrust.

However, the Japan Aerospace Exploration Agency (JAXA) has recently completed a successful test of a different type of rocket, known as a rotating detonation engine. The engine relies on an entirely different method of combustion, with the aim to produce more thrust from less fuel. We’ll dive into how it works, and how the Japanese test bodes for the future of this technology.

Deflagration vs. Detonation

Humans love combusting fuels in order to do useful work. Thus far in our history, whether we look at steam engines, gasoline engines, or even rocket engines, all these technologies have had one thing in common: they all rely on fuel that burns in a deflagration. It’s the easily controlled manner of slow combustion that we’re all familiar with since we started sitting around campfires. Continue reading “Japanese Rocket Engine Explodes: Continuously And On Purpose” →

Printing Ceramics Made Easier

August 30, 2021 by 3 Comments

Creating things with ceramics is nothing new — people have done it for centuries. There are ways to 3D print ceramics, too. Well, you typically 3D print the wet ceramic and then fire it in a kiln. However, recent research is proposing a new way to produce 3D printed ceramics. The idea is to print using TPU which is infused with polysilazane, a preceramic polymer. Then the resulting print is fired to create the final ceramic product.

The process relies on a specific type of infill to create small channels inside the print to assist in the update of the polysilazane. The printer was a garden-variety Lulzbot TAZ 6 with ordinary 0.15mm and 0.25mm nozzles.

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Fusion Ignition: What Does The NIF’s 1.3 MJ Yield Mean For Fusion Research?

August 30, 2021 by 37 Comments

Earlier this month, Lawrence Livermore National Laboratory (LLNL) announced to the world that they had achieved a record 1.3 MJ yield from a fusion experiment at their National Ignition Facility (NIF). Yet what does this mean, exactly? As their press release notes, the main advancement of these results will go towards the US’s nuclear weapons arsenal.

This pertains specifically to the US’s nuclear fusion weapons, which LLNL along with Los Alamos National Laboratory (LANL) and other facilities are involved in the research and maintenance of. This traces back to the NIF’s roots in the 1990s, when the stockpile stewardship program was set up as an alternative to nuclear weapons testing. Much of this research involves examining how today’s nuclear weapons degrade over time, and ways to modernize the existing arsenal.

In light of this, one may wonder what the impact of these experimental findings from the NIF are beyond merely ensuring that the principle of MAD remains intact. To answer that question, we have to take a look at inertial confinement fusion (ICF), which is the technology at the core of the NIF’s experiments.

Continue reading “Fusion Ignition: What Does The NIF’s 1.3 MJ Yield Mean For Fusion Research?” →

Turning Heat Into Electricity

August 28, 2021 by 7 Comments

You don’t really create energy, you convert it from one form to another. For example, many ways that we generate electricity use heat from burning or nuclear decay to generate steam which turns a generator. Thermocouples generate electricity directly from heat, but generally not very much. Still, some nuclear batteries directly convert heat to electricity, they just aren’t very efficient. Now researchers have developed a way of preparing a material that is better at doing the conversion: tin selenide.

Tin selenide is known to have good performance converting heat into electricity when in its crystal form. However, practical applications are more likely to use polycrystalline forms, which are known to have reduced conversion performance.

The material works well because it is not very thermally conductive and it has a favorable band structure that allows multiple bands to participate in charge transport. However, in polycrystal configurations, the results are not as good due to higher thermal conductivity. Yet crystalline tin selenide is difficult to manufacture and not very robust in real-world use.

The team worked out that the polycrystal material’s thermal properties were due to tin oxide films on the surface. Using a particular method of construction, you can remove the tin oxide and improve performance even better than the crystal version of tin selenide.

Creating this material might be beyond your garage lab, though. You need a fused silica oven that can reach a pretty tight vacuum. Although you might be able to swing it. Otherwise, you might stick with more conventional methods.

Ultrasonic levitation rig.

Phased Array Levitation Is Science In Action

August 18, 2021 by 8 Comments

Levitation may seem like magic. However, for certain objects, and in certain conditions, it’s actually a solved technology. If you want to move small particles around or do experiments with ultrasonic haptic feedback, you might find SonicSurface to be a useful platform for experimentation.

The build comes to us from [UpnaLab], and is no small feat of engineering. It packs in 256 ultrasonic emitters in a 16×16 grid, with individual phase control across the entire panel. This allows for the generation of complex ultrasonic wave fields over the SonicSurface board. Two boards can be paired together in a vertically opposed configuration, too. This allows the levitation of tiny particles in 3D space.

As you might expect, an FPGA is pressed into service to handle the heavy lifting – in this case, an Altera CoreEP4CE6. Commands are sent to the SonicSurface by a USB-to-serial connection from an attached PC.

The board is largely limited to the levitation of small spherical pieces of foam, with the ultrasonic field levitating them in midair. However, the project video shows how these tiny pieces of foam can be attached to threads, tapes, and other objects in order to manipulate them with the ultrasonic array.

It may not be a simple project, but it serves as a great basis for your own levitation experiments. Of course, if you want to start smaller, that’s fine too. If you come up with any great levitation breakthroughs of your own, be sure to let us know.

Golden Rice’s Appearance On Philippine Store Shelves And The Rise Of Biofortification

August 18, 2021 by 45 Comments

After decades in development, the Philippines became the first country on July 21st of this year to formally approve the commercial propagation of so-called golden rice. This is a rice strain that has been genetically engineered to produce beta-carotene in its grains. This is the same compound that has made carrots so famous, and is a significant source of vitamin A.

Getting enough vitamin A is essential for not only children and newborns, but also for pregnant and lactating women. Currently, vitamin A deficiency (VAD) is the primary cause of preventable childhood blindness and an important cause of infant mortality. While VAD is hardly the only major form of world-wide malnutrition, biofortification efforts like golden rice stand to dramatically improve the lives of millions of people around the globe by reducing the impact of VAD.

This raises questions of how effective initiatives like golden rice are likely to be, and whether biofortification of staple foods may become more common in the future, including in the US where fortification of foods has already become commonplace. Continue reading “Golden Rice’s Appearance On Philippine Store Shelves And The Rise Of Biofortification” →