A Compact Electrohydrodynamic Pump Using Copper And TPU

June 9, 2024 by Maya Posch 21 Comments

Electrohydrodynamics (EHD) involves the dynamics of electrically charged fluids, which effectively means making fluids move using nothing but electric fields, making it an attractive idea for creating a pump out of. This is the topic of a 2023 paper by [Michael Smith] and colleagues in Science, titled “Fiber pumps for wearable fluidic systems”. The ‘fiber pumps’ as they call the EHD pumps in this study are manufactured by twisting two helical, 80 µm thick copper electrodes around a central mandrel, along with TPU (thermoplastic polyurethane) before applying heat. This creates a tube where the two continuous electrodes are in contact with any fluids inside the tube.

For the fluid a dielectric fluid is required to create the ions, which was 3M Novec 7100, a methoxy-fluorocarbon. Because of the used voltage of 8 kV, a high electrical breakdown of the fluid is required. After ionization the required current is relatively low, with power usage reported as 0.9 W/m, with one meter of this pump generating a pressure of up to 100 kilopascals and a flowrate of 55 mL/minute. One major limitation is still that after 6 days of continuous pumping, the copper electrodes are rendered inert due to deposits, requiring the entire system to be rinsed. Among the applications the researchers see artificial muscles and flexible tubing in clothing to cool, heat and provide sensory feedback in VR applications.

While the lack of moving parts as with traditional pumps is nice, the limitations are still pretty severe. What is however interesting about this manufacturing method is that it is available to just about any hobbyist who happens to have some copper wiring, TPU filament and something that could serve as a mandrel lying around.

Thanks to [Aaron Eiche] for the tip.

Fourier, The Animated Series

June 5, 2024 by Al Williams 7 Comments

We’ve seen many graphical and animated explainers for the Fourier series. We suppose it is because it is so much fun to create the little moving pictures, and, as a bonus, it really helps explain this important concept. Even if you already understand it, there’s something beautiful and elegant about watching a mathematical formula tracing out waveforms.

[Andrei Ciobanu] has added his own take to the body of animations out there — or, at least, part one of a series — and we were impressed with the scope of it. The post starts with the basics, but doesn’t shy away from more advanced math where needed. Don’t worry, it’s not all dull. There’s mathematical flowers, and even a brief mention of Pink Floyd.

The Fourier series is the basis for much of digital signal processing, allowing you to build a signal from the sum of many sinusoids. You can also go in reverse and break a signal up into its constituent waves.

We were impressed with [Andrei’s] sinusoid Tetris, and it appears here, too. We’ve seen many visualizers for this before, but each one is a little different.

Mechanic Prince Of Tides

June 5, 2024 by Al Williams 2 Comments

Lord Kelvin’s name comes up anytime you start looking at the history of science and technology. In addition to working on transatlantic cables and thermodynamics, he also built an early computing device to predict tides. Kelvin, whose real name was William Thomson, became interested in tides in a roundabout way, as explained in a recent IEEE Spectrum article.

He’d made plenty of money on his patents related to the telegraph cable, but his wife died, so he decided to buy a yacht, the Lalla Rookh. He used it as a summer home. If you live on a boat, the tides are an important part of your day.

Today, you could just ask your favorite search engine or AI about the tides, but in 1870, that wasn’t possible. Also, in a day when sea power made or broke empires, tide charts were often top secret. Not that the tides were a total mystery. Newton explained what was happening back in 1687. Laplace realized they were tied to oscillations almost a century later. Thomson made a machine that could do the math Laplace envisioned.

We know today that the tides depend on hundreds of different motions, but many of them have relatively insignificant contributions, and we only track 37 of them, according to the post. Kelvin’s machine — an intricate mesh of gears and cranks — tracked only 10 components.

In operation, the user turned a crank, and a pen traced a curve on a roll of paper. A small mark showed the hour with a special mark for noon. You could process a year’s worth of tides in about 4 hours. While Kelvin received credit for the machine’s creation, he acknowledged the help of many others in his paper, from craftsmen to his brother.

We actually did a deep dive into tides, including Kelvin’s machine, a few years ago. He shows up a number of times in our posts.

Can You Hear Me Now? Try These Headphones

May 29, 2024 by Al Williams 12 Comments

When you are young, you take it for granted that you can pick out a voice in a crowded room or a factory floor. But as you get older, your hearing often gets to the point where a noisy room merges into a mishmash of sounds. University of Washington researchers have developed what they call Target Speech Hearing. In plain English, it is an AI-powered headphone that lets you look at someone and pull their voice out of the chatter. For best results, however, have to enroll their voice first, so it wouldn’t make a great eavesdropping device.

If you want to dive into the technical details, their paper goes into how it works. The prototype uses a Sony noise-cancelling headset. However, the system requires binaural microphones so additional microphones attach to the outside of the headphones.

Continue reading “Can You Hear Me Now? Try These Headphones” →

The Genius Of Slide Rule Precision

May 29, 2024 by Maya Posch 50 Comments

Most people have heard of or seen slide rules, with older generations likely having used these devices in school and at their jobs. As purely analog computers these ingenious devices use precomputed scales on slides, which when positioned to a specific input can give the output to a wide range of calculations, ranging from simple divisions and multiplications to operations that we generally use a scientific calculator for these days. Even so, these simple devices are both very versatile and can be extremely precise, as [Bob, the Science Guy] demonstrates in a recent video.

Slide rules at their core are very simple: you got different scales (marked by a label) which can slide relative to each other. Simple slide rules will only have the A through D scales, with an input provided by moving one scale relative to the relevant other scale (e.g. C and D for multiplication/division) after which the result can be read out. Of course, it seems reasonable that the larger your slide rule is, the more precision you can get out of it. Except that if you have e.g. the W1 and W2 scales on a shorter (e.g. 10″) slide rule, you can use those to get the precision of a much larger (20″) slide rule, as [Bob] demonstrates.

Even though slide rules have a steeper learning curve than punching numbers into a scientific calculator, it is hard to argue the benefits of understanding such relationships between the different scales, and why they exist in the first place.

Continue reading “The Genius Of Slide Rule Precision” →

Whole-Fruit Chocolate: Skipping The Sugar By Using The Entire Cacao Pod

May 28, 2024 by Maya Posch 34 Comments

Images of whole-fruit chocolate formulations after kneading at 31 °C and subsequent heating to 50 °C. The ECP concentration in the sweetening gel and the added gel concentrations into the CM are shown on the x and y axis, respectively. (Credit: Kim Mishra et al., Nature Food, 2024) — Images of whole-fruit chocolate formulations after kneading at 31 °C and subsequent heating to 50 °C. The ECP concentration in the sweetening gel and the added gel concentrations in the CM are shown on the X and Y axes, respectively. (Credit: Kim Mishra et al., Nature Food, 2024)

It’s hard to imagine a world without chocolate, and yet it is undeniable that there are problems associated both with its manufacturing and its consumption. Much of this is due to the addition of sugar, as well as the discarding of a significant part of the cacao pod, which harbors the pulp and seeds. According to a study by [Kim Mishra] and colleagues in Nature Food, it might be possible to ditch the sugar and instead use a mixture of cacao pulp juice (CPJC) and endocarp powder (ECP), which are turned into a sweetening gel.

This gel replaces the combination of sugar with an emulsifier (lecithin or something similar) in current chocolate while effectively using all of the cacao pod except for the husk. A lab ran a small-scale production, with two different types of whole-fruit chocolate produced, each with a different level of sweetness, and given to volunteers for sampling. Samples had various ECP ratios in the gel and gel ratios in the chocolate mixture with the cacao mass (CM).

With too much of either, the chocolate becomes crumbly, while with too little, no solid chocolate forms. Eventually, they identified a happy set of ratios, leading to the taste test, which got an overall good score in terms of chocolate taste and sweetness. In addition to being able to skip the refined sugar addition, this manufacturing method also cuts out a whole supply chain while adding significantly more fiber to chocolate. One gotcha here is that this study focused on dark chocolate, but then some chocolate fans would argue vehemently that anything below 50% cacao doesn’t qualify as chocolate anymore, while others scoff at anything below 75%.

Matters of taste aside, this study shows a promising way to make our regular chocolate treat that much healthier and potentially greener. Of course, we want to know how it will print. Barring that, maybe how it engraves.

Recycling Of Portland Cement And Steel In Electric Arc Furnaces

May 27, 2024 by Maya Posch 25 Comments

The use of concrete and steel have both become the bedrock of modern-day construction, which of course also means that there is a lot of both which ends up as waste once said construction gets demolished again. While steel is readily recyclable, the Portland cement that forms the basis of concrete so far is not. Although the aggregate from crushed concrete can be reclaimed, the remainder tends to end up in a landfill, requiring fresh input of limestone to create more cement. Now a team of researchers from the University of Cambridge claim to have found a way to recycle hydrated Portland cement by using it as flux during steel production in electric arc furnaces (EAFs).

Not only does this save a lot of space in landfills, it also stands to reduce a lot of the carbon dioxide produced during cement and steel production, which is primarily from the use of limestone for cement and lime-dolomite for steel. The details can be found in the open access paper in Nature by [Cyrille F. Dunant] and colleagues. Essentially reclaimed cement paste is mixed with some fresh material to form the flux that shields the molten steel in an EAF from the atmosphere. The flux creates the slag layer that floats on top of the molten steel, with this slag after cooling down being ground up and turned into cement clinker, which is then mixed to create fresh cement.

The process has been patented by Cambridge, who call the product ‘Cambridge Electric Cement‘, with the claim that if using low-carbon power sources for the EAF like hydro and nuclear, it would constitute ‘no emissions’ and ‘no landfill’ cement. We have to see how this works out on an industrial scale, of course, but it would definitely be nice to keep concrete and cement in general out of landfills, while cutting back on limestone mining, as well as questionable practices like adding heavy metal-laden fly ash as filler to concrete.

Thanks to [cscott] for the tip.