Homebrew Electron Beam Lithography With A Scanning Electron Microscope

December 19, 2024 by 7 Comments

If you want to build semiconductors at home, it seems like the best place to start might be to find a used scanning electron microscope on eBay. At least that’s how [Peter Bosch] kicked off his electron beam lithography project, and we have to say the results are pretty impressive.

Now, most of the DIY semiconductor efforts we’ve seen start with photolithography, where a pattern is optically projected onto a substrate coated with a photopolymer resist layer so that features can be etched into the surface using various chemical treatments. [Peter]’s method is similar, but with important differences. First, for a resist he chose poly-methyl methacrylate (PMMA), also known as acrylic, dissolved in anisole, an organic substance commonly used in the fragrance industry. The resist solution was spin-coated into a test substrate of aluminized Mylar before going into the chamber of the SEM.

As for the microscope itself, that required a few special modifications of its own. Rather than rastering the beam across his sample and using a pattern mask, [Peter] wanted to draw the pattern onto the resist-covered substrate directly. This required an external deflection modification to the SEM, which we’d love to hear more about. Also, the SEM didn’t support beam blanking, meaning the electron beam would be turned on even while moving across areas that weren’t to be exposed. To get around this, [Peter] slowed down the beam’s movements while exposing areas in the pattern, and sped it up while transitioning to the next feature. It’s a pretty clever hack, and after development and etching with a cocktail of acids, the results were pretty spectacular. Check it out in the video below.

It’s pretty clear that this is all preliminary work, and that there’s much more to come before [Peter] starts etching silicon. He says he’s currently working on a thermal evaporator to deposit thin films, which we’re keen to see. We’ve seen a few sputtering rigs for thin film deposition before, but there are chemical ways to do it, too.

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Close up of a typewriter annex SMS-receiver

Back To The Future Of Texting: SMS On A Panasonic Typewriter

December 18, 2024 by 4 Comments

Among us Hackaday writers, there are quite a few enthusiasts for retro artifacts – and it gets even better when they’re combined in an unusual way. So, when we get a tip about a build like this by [Sam Christy], our hands sure start itching.

The story of this texting typewriter is one that beautifully blends nostalgia and modern technology. [Sam], an engineering teacher, transformed a Panasonic T36 typewriter into a device that can receive SMS messages, print them out, and even display the sender’s name and timestamp. For enthusiasts of retro gadgets, this creation bridges the gap between analog charm and digital convenience.

What makes [Sam]’s hack particularly exciting is its adaptability. By effectively replacing the original keyboard with an ESP32 microcontroller, he designed the setup to work with almost any electric typewriter. The project involves I2C communication, multiplexer circuits, and SMS management via Twilio. The paper feed uses an “infinite” roll of typing paper—something [Sam] humorously notes as outlasting magnetic tape for storage longevity.

Beyond receiving messages, [Sam] is working on features like replying to texts directly from the typewriter. For those still familiar with the art form of typing on a typewriter: how would you elegantly combine these old machines with modern technology? While you’re thinking, don’t overlook part two, which gives a deeper insight in the software behind this marvel!

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Survival mechanisms in Deinococcus radiodurans bacterium. (Credit: Feng Liu et al., 2023)

Bacterium Demonstrates Extreme Radiation Resistance Courtesy Of An Antioxidant

December 18, 2024 by 12 Comments

Extremophile lifeforms on Earth are capable of rather astounding feats, with the secret behind the extreme radiation resistance of one of them now finally teased out by researchers. As one of the most impressive extremophiles, Deinococcus radiodurans is able to endure ionizing radiation levels thousands of times higher than what would decisively kill a multicellular organism like us humans. The trick is the antioxidant which this bacterium synthesizes from multiple metabolites that combine with manganese. An artificial version of this antioxidant has now been created that replicates the protective effect.

The ternary complex dubbed MDP consists of manganese ions, phosphate and a small peptide, which so far has seen application in creating vaccines for chlamydia. As noted in a 2023 study in Radiation Medicine and Protection by [Feng Liu] et al. however, the D. radiodurans bacterium has more survival mechanisms than just this antioxidant. Although much of the ionizing radiation is neutralized this way, it can not be fully prevented. This is where the highly effective DNA repair mechanism comes into play, along with a range of other adaptations.

The upshot of this is the synthesis of a very effective and useful antioxidant, but as alluded to in the press releases, just injecting humans with MDP will not instantly give them the same super powers as our D. radiodurans buddy.

Featured image: Survival mechanisms in Deinococcus radiodurans bacterium. (Credit: Feng Liu et al., 2023)

Simple Fluorometer Makes Nucleic Acid Detection Cheap And Easy

December 18, 2024 by 9 Comments

Back in the bad old days, dealing with DNA and RNA in a lab setting was often fraught with peril. Detection technologies were limited to radioisotopes and hideous chemicals like ethidium bromide, a cherry-red solution that was a fast track to cancer if accidentally ingested. It took time, patience, and plenty of training to use them, and even then, mistakes were commonplace.

Luckily, things have progressed a lot since then, and fluorescence detection of nucleic acids has become much more common. The trouble is that the instruments needed to quantify these signals are priced out of the range of those who could benefit most from them. That’s why [Will Anderson] et al. came up with DIYNAFLUOR, an open-source nucleic acid fluorometer that can be built on a budget. The chemical principles behind fluorometry are simple — certain fluorescent dyes have the property of emitting much more light when they are bound to DNA or RNA than when they’re unbound, and that light can be measured easily. DIYNAFLUOR uses 3D-printed parts to hold a sample tube in an optical chamber that has a UV LED for excitation of the sample and a TLS2591 digital light sensor to read the emitted light. Optical bandpass filters clean up the excitation and emission spectra, and an Arduino runs the show.

The DIYNAFLUOR team put a lot of effort into making sure their instrument can get into as many hands as possible. First is the low BOM cost of around $40, which alone will open a lot of opportunities. They’ve also concentrated on making assembly as easy as possible, with a solder-optional design and printed parts that assemble with simple fasteners. The obvious target demographic for DIYNAFLUOR is STEM students, but the group also wants to see this used in austere settings such as field research and environmental monitoring. There’s a preprint available that shows results with commercial fluorescence nucleic acid detection kits, as well as detailing homebrew reagents that can be made in even modestly equipped labs.

Push For On, Hold For Off, AC Edition

December 18, 2024 by 18 Comments

A common theme in modern consumer electronics is having a power button that can be tapped to turn the device on, but needs to be held down when it’s time to shut it off. [R. Jayapal] had noticed a circuit design for this setup when using DC and decided to create a version that could handle AC-powered loads.

The circuit relies on a classic optoisolated triac to switch the AC line, although [R. Jayapal] notes that a relay would also work. The switch circuit consists of two transistors, a comparator, a flip flop and a monostable. As you might expect, the button triggers the flip flops to turn the triac on. However, if you hold the switch for more than a few seconds, a capacitor charges and causes the comparator to trip the output flip flop.

The DC circuit that inspired this one is naturally a bit simpler, although we might have been tempted to simply use the output of that circuit to drive a relay or triac. On the other hand, the circuit is set up to allow you to adjust the time delay easily.

Given the collection of parts, though, we wonder if you couldn’t press some 555s into service for this to further reduce the part count. If relays are too old-fashioned for you, you can always use a solid-state relay or make your own.

Upper Room UV-C Keeps Air Cleaner

December 18, 2024 by 59 Comments

2020 saw the world rocked by widespread turmoil, as a virulent new pathogen started claiming lives around the globe. The COVID-19 pandemic saw a rush on masks, air filtration systems, and hand sanitizer, as terrified populations sought to stave off the deadly virus by any means possible.

Despite the fresh attention given to indoor air quality and airborne disease transmission, there remains one technology that was largely overlooked. It’s the concept of upper-room UV sterilization—a remarkably simple way of tackling biological nastiness in the air.

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