Holograms: The Future Of Speedy Nanoscale 3D Printing?

April 9, 2023 by Dave Rowntree 7 Comments

3D printing by painting with light beams on a vat of liquid plastic was once the stuff of science fiction, but now is very much science-fact. More than that, it’s consumer-level technology that we’re almost at the point of being blasé about. Scientists and engineers the world over have been quietly beavering away in their labs on the new hotness, nanoscale 3D printing with varying success. Recently IEESpectrum reports some promising work using holographic imaging to generate nanoscale structures at record speed.

Current stereolithography printers make use of UV laser scanned over the bottom of a vat of UV-sensitive liquid photopolymer resin, which is chemically tweaked to make it sensitive to the UV frequency photons. This is all fine, but as we know, this method is slow and can be of limited resolution, and has been largely superseded by LCD technology. Recent research has focussed on two-photon lithography, which uses a resin that is largely transparent to the wavelength of light concerned, but critically, can be polymerized with enough energy density (i.e. the method requires multiple photons to be simultaneously absorbed.) This is achieved by using pulsed-mode lasers to focus to a very tight point, giving the required huge energy density. This tight focus, plus the ability to pass the beam through the vat of liquid allows much tighter image resolution. But it is slow, painfully slow.

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CNC Intaglio-Esque Engraving

March 24, 2023 by Dave Rowntree 3 Comments

Intaglio is an ancient carving technique for adding details to a workpiece, by manually removing material from a surface with only basic hand tools. If enough material depth is removed, the resulting piece can be used as a stamp, as was the case with rings, used to stamp the wax seals of verified letters. [Nicolas Tranchant] works in the jewelry industry, and wondered if he could press a CNC engraving machine into service to engrave gemstones in a more time-efficient manner than the manual carving methods of old.

Engraving and machining generally work only if the tool you are using is mechanically harder than the material the workpiece is made from. In this case, this property is measured on the Mohs scale, which is a qualitative measurement of the ability of one (harder) material to scratch another. Diamond is the hardest known material on the Mohs scale and has a Mohs hardness of 10, so it can produce a scratch on the surface of say, Corundum — Mohs value 9 — but not the other way around.

[Nicolas] shows the results of using a diamond tip equipped CNC engraver on various gemstones typical of Intaglio work, such as Black Onyx, Malachite, and Amethyst with some details of the number of engraving passes needed and visual comparison to the same material treated to traditional carving.

Let’s be clear here, the traditional intaglio process produces deep grooves on the surface of the workpiece and the results are different from this simple multi-pass engraving method — but limiting the CNC machine to purely metal engraving duties seemed a tad wasteful. Now if they can only get a suitable machine for deeper engraving, then custom digitally engraved intaglio style seal rings could be seeing a comeback!

Intaglio isn’t just about jewelry of course, the technique has been used in the typesetting industry for centuries. But to bring this back into ours, here’s a little something about making a simple printing press.

Ondol: Korean Underfloor Heating

March 23, 2023 by Dave Rowntree 49 Comments

One of the many aspects of the modern world we often take for granted is the very technology that keeps our accommodation at a habitable temperature. Examples of this include centralized heating systems using hot-water circulation, or blown air ducted to multiple rooms from a central furnace. Certainly in Europe, once the Romans shipped out, and before the industrial revolution, we were pretty cold unless someone lit a fire in the room. Every room. But not in Korea. The Ondol heating principles have been used constantly from about 5000 BC to only a few decades ago, keeping your average Korean countryman nice and toasty.

Having said that, the sophistication has improved a bit. Initially, the idea was to simply heat up a bunch of rocks in the fire, and bring them indoors, but Ondol quickly became part of the building itself. As will be seen from the video embedded below, the house sits on top of an elaborate double stack of serpentine channels, that circulate the hot combustion products from the furnace as thoroughly as possible, slowing down the gases and allowing their heat to transfer into the structure of the floor, and then radiate into the space above. It does bear more than a passing resemblance to the Roman hypocaust system, ruined examples of which can be found all over the UK and Europe. The skill demonstrated in the video is considerable, but must surely be an expensive build reserved for the most culturally aware Koreans who wish to live in simpler (and less hectic) locations in their country.

Maybe for the vast majority of us, this kind of thing is not viable, and we’re more likely to benefit from a more centralized approach, perhaps using waste heat from data centers or geothermal activity. (See: Iceland)

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Who Needs Gasoline When You’ve Got Sodium?

March 23, 2023 by Dave Rowntree 58 Comments

YouTuber and serial debunker [Thunderf00t] was thinking about the use of sodium to counteract global warming. The theory is that sodium can be used as a fuel when combusted with air, producing a cloud of sodium hydroxide which apparently can have a cooling effect if enough of it is kicking around the upper atmosphere. The idea is to either use sodium directly as a fuel, or as a fuel additive, to increase the aerosol content of vehicle emissions and maybe reduce their impact a little.

One slight complication to using sodium as a fuel is that it’s solid at room temperature, so it would need to be either delivered as pellets or in liquid form. That’s not a major hurdle as the melting point is a smidge below 100 degrees Celsius and well within the operating region of an internal combustion engine, but you can imagine the impact of metal solidifying in your fuel system. Luckily, just like with solder eutectic mixes, sodium-potassium alloy happens to remain in liquid form at handleable temperatures and only has a slight tendency to spontaneously ignite. So that’s good.

Initial experiments using ultrasonic evaporators proved somewhat unsuccessful due to the alloy’s electrical conductivity and tendency to set everything on fire. The next attempt was using a standard automotive fuel injector from the petrol version of the Ford Fiesta. Using a suitable container, a three-way valve to allow the introduction of fuels, and an inert argon feed (preventing spontaneous combustion in the air), delivering the liquid metal fuel into the fuel injector seems straightforward enough.

[Thunderf00t] started with ethanol, then worked up to pentane before finally attempting to use the feisty sodium-potassium, once the bugs had been shaken out of the high-speed video setup. [Thunderf00t] does stress the importance of materials selection when handling this potential liquid metal fuel, since it apparently just bursts into flames in a violent manner on contact with incompatible materials. Heck, this stuff even reacts with PTFE, which is generally considered a very resistant material. We’re totally convinced we’d not like to see this stuff being pumped from a roadside gas station, at all, but it sure is a fun concept to think about.

Sodium-Potassium alloy doesn’t feature on these pages too often, but here’s a little fountain of the stuff, just because why not?

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Supercon 2022: Irak Mayer Builds Self-Sustainable Outdoor IoT Devices

March 13, 2023 by Dave Rowntree 4 Comments

[Irak Mayer] has been exploring IoT applications for use with remote monitoring of irrigation control systems. As you would expect, the biggest challenges for moving data from the middle of a field to the home or office are with connectivity and power. Obviously, the further away from urbanization you get, the sparser both these aspects become, and the greater the challenge.

[Irak] solves his connectivity problem by assuming there is some WiFi network within range, building a system around the Blues Wireless WiFi note card. Substituting their cellular card would be an option for applications out of WiFi range, but presumably without changing too much on the system and software side of things. Leveraging the Adafruit FeatherWing INA219, which is a bidirectional current sensor with an I²C interface, for both the power generation and system consumption measurements. For control, [Irak] is using an Adafruit ESP32 board, but says little more about the hardware. On the software side, [Irak] is using the Blues Wireless NoteHub for the initial connection, which then routes the collected data onto the Adafruit IoT platform for collation purposes. The final part of the hardware is a LiPo battery which is on standby to soak up any excess power available from the energy harvesting. This is monitored by an LC709203f battery fuel gauge.

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SUPERCON 2022: Kuba Tyszko Cracks Encrypted Software

February 21, 2023 by Dave Rowntree 5 Comments

[Kuba Tyszko] like many of us, has been hacking things from a young age. An early attempt at hacking around with grandpa’s tractor might have been swiftly quashed by his father, but likely this was not the last such incident. With a more recent interest in cracking encrypted applications, [Kuba] gives us some insights into some of the tools at your disposal for reading out the encrypted secrets of applications that have something worth hiding. (Slides here, PDF.)

There may be all sorts of reasons for such applications to have an encrypted portion, and that’s not really the focus. One such application that [Kuba] describes was a pre-trained machine-learning model written in the R scripting language. If you’re not familiar with R, it is commonly used for ‘data science’ type tasks and has a big fan base. It’s worth checking out. Anyway, the application binary took two command line arguments, one was the encrypted blob of the model, and the second was the path to the test data set for model verification.

The first thing [Kuba] suggests is to disable network access, just in case the application wants to ‘dial home.’ We don’t want that. The application was intended for Linux, so the first port of call was to see what libraries it was linked against using the ldd command. This indicated that it was linked against OpenSSL, so that was a likely candidate for encryption support. Next up, running objdump gave some clues as to the various components of the binary. It was determined that it was doing something with 256-bit AES encryption. Now after applying a little experience (or educated guesswork, if you prefer), the likely scenario is that the binary yanks the private key from somewhere within itself reads the encrypted blob file, and passes this over to libssl. Then the plaintext R script is passed off to the R runtime, the model executes against the test data, and results are collated.

[Kuba]’s first attack method was to grab the OpenSSL source code and drop in some strategic printf() function calls into the target functions. Next, using the LD_PRELOAD ‘trick’ the standard system OpenSSL library was substituted with the ‘fake’ version with the trojan printfs. The result of this was the decryption function gleefully sending the plaintext R script direct to the terminal. No need to even locate the private key!

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A Low Budget DIY Vibrotactile Stimulator For Experimental CRS

February 18, 2023 by Dave Rowntree 7 Comments

Modern techniques of Coordinated Reset Stimulation (CRS), which is usually administered with invasive deep brain stimulation, can have a miraculous effect on those suffering from Parkinson’s disease. However, the CRS technique can also apparently be administered via so-called vibrotactile CRS (vCRS) which essentially means vibrating certain nerve endings corresponding to brain regions that have a large cortical representation.

An example is vibrating the tips of the fingers using special gloves. This is a medical technique and as such is governed by the FDA. With ongoing trials, patients all around the world will simply have to wait. [HackyDev] has been working with a group of people on developing an open source vCRS glove.

This neuromodulation technique seems so promising, that this upfront effort by hackers around the world is simply a joy to see. Patents be dammed; we can work around them. Interested parties can follow the (very long, tricky-to-follow) thread here.

The hardware [HackyDev] put together uses a nodeMCU as the controller, driving eight motor coils via MOSFETS. The finger-mounted actuators are constructed by ripping the electromagnet out of a relay and mounting it in a 3D printed frame, with a magnet suspended on a spring. This part is mounted on each finger. The nodeMCU presents a simple web form that enables the configuration of the pulse parameters.

A permanent magnet is housed in the spring’s top section

The way the gloves appear to work is due to the way the body perceives sensory input, with a massive bias towards the hands and mouth region, referred to as the cortical homunculus. Each finger has an individual haptic element, which is actuated in a specific sequence with a carefully formed pulse at approx. 250 Hz.

This appears to activate similar in-brain effects as traditional (and invasive) DBS therapy by effectively de-synchronizing certain over-synchronized brain pathways and alleviating the overactive ß-wave activity in the brain. And this calms the tremors as well as many other PD symptoms. It’s all very exciting stuff, and we’ll be following this story closely.

For more on the backstory check out the 2017 paper by Peter A. Tass, as well as this later one, and this one. We’ve seen some recent success with diagnosing or at least detecting PD, by smell as well as via audio, so the future might look a little brighter for quite a number of people.