A Microneedle Vaccine Patch Printer For Thermostable MRNA Vaccines

April 30, 2023 by 95 Comments

What if you could get vaccinated with the ease of putting on an adhesive bandage? This is the promise of microneedle patches (MNP), which are essentially what they sound like. These would also have uses in diagnostics that might one day obliviate the need for drawing blood. The one major issue with MNPs is their manufacturing, which has been a laborious and highly manual process. In a recent paper in Nature Biotechnology researchers detail the construction and testing of a MNP printer, or microneedle vaccine printer (MVP) that can print dissolving polymers containing stabilized mRNA vaccine.

These mRNA strands are as usual encapsulated in a liquid nanoparticle container, which is mixed with the soluble and biocompatible polymer. This mixture is then added to a mold and dried, after which it retains the microneedle structure of the mold. On tests involving pig skin, the MNPs were capable of penetrating the skin and delivering the vaccine contained in the needles. Produced patches were shown to be shelf-stable for at least six months, which would make these ideal for vaccine distribution in areas where refrigeration and similar are problematic.

Using MNPs for delivering vaccines has previously been researched for e.g. delivering rotavirus and poliovirus vaccine, and a 2021 study in Nature Biomedical Engineering looked at the viability of using MNPs to rapidly sample protein biomarkers in interstitial fluid, which could make diagnostics for certain biomarkers as uncomplicated as putting on the patch, removing it and examining it, removing the need for drawing blood or sampling large amounts of interstitial fluid for external analysis.

If the concept of the MVP and similar MNP printers can be commercialized, it might make it possible to strongly shorten the supply chain for vaccines in less developed regions, while also enabling diagnostics that are very costly and cumbersome today.

Embed Hardware Into 3D Prints, But Not In The Way You’re Thinking

April 30, 2023 by 9 Comments

[Christopher Helmke] is doing fantastic work in DIY systems for handling small hardware like fasteners, and that includes robotic placement of hardware into 3D prints. Usually this means dropping nuts into parts in mid-print so that the hardware is captive, but that’s not really the story here.

The really inventive part we want to highlight is the concept of reducing packaging and labor. Instead of including a zip-lock bag of a few bolts, how about embedding the bolts into a void in the 3D print, covered with a little snip-out retainer? Skip ahead to 1:54 in the video to see exactly what we mean. It’s a pretty compelling concept that we hope sparks a few ideas in others.

As clever as that concept is, the rest of the video is also worth a watch because [Christopher] shows off a DIY system that sits on top of his 3D printer and takes care of robotically placing the hardware in mid-print. He talks all about the challenges of such a system. It’s not perfect (yet), but seeing it in action is very cool.

We’ve recently seen a lot of fascinating stuff when it comes to [Christopher Helmke]’s automated handling of fasteners and similar hardware. His system makes rapid and accurate dispensing of bolts look easy, and his work on using compressed air to zip pieces around seems effective.

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Add A Little Quindar To Your Comms For That Apollo-Era Sound

April 30, 2023 by 9 Comments

If there’s one thing that ties together all the media coming out of the Apollo era, it’s probably the iconic Quindar tones. These quarter-second beeps served as control tones for the globe-spanning communications network needed to talk to the Apollo astronauts, and any attempt to recreate the Apollo-era sound would be glaringly wrong without them. And that’s why [CuriousMarc] whipped up this Quindar tone system.

The video below starts with a detailed treatment of what Quindar tones are and why they were used, a topic we’ve covered ourselves in the past. To recap, Quindar tones are a form of in-band signaling, with a 2,525-Hz pure sine wave intro tone that signaled the transmitters connected to Mission Control in Houston over leased telephone lines to key up. The 2,475-Hz outro tone turned off the transmitters and connected the line to the receivers.

To recreate the sound quality of the original circuitry, and to keep in the retro vibe, [Marc]’s Quindar homage avoided digital circuitry as much as possible, opting instead to generate the two tones with an XR-2206 function generator chip. The chip can rapidly switch back and forth between two frequencies, making it perfect for FSK applications or, in this case, reproducing the two slightly different tones. [Marc] added a dual mono-stable multi-vibrator to pulse the tone, giving the 250-ms pulse, and an audio gate, which uses a MOSFET to switch the tone into an audio stream. All this got soldered up to a piece of perf board and stuffed in the base of a cheap intercom microphone, which while not period accurate still has a cool retro look — and now, a retro sound, too.

Hats off to [CuriousMarc] and his merry band for probing the mysteries of Apollo-era comms and keeping the accomplishments of all those engineers alive. The methods they used are still relevant after all these years, and there seems to be no end to what we can learn from them.

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When Your Smart Light Switches Stop Working, Build Your Own

April 30, 2023 by 14 Comments

If you want smart light switches in your house, you can buy from any one of hundreds of manufacturers. [Brian Boyle] had kitted out his home with TP Link devices, but after a few years of use, he found they all suddenly failed within a few months of each other. Decrying the state of things, he set about building his own instead.

[Brian]’s switches use the ESP32 for its handy in-built WiFi hardware. His aim was to produce smart switches that would fit neatly into standard “Decor” style switch boxes. The design uses two PCBs. One is charged with handling the mains power side of things. It carries an SPDT relay for switching AC power, and a DC power supply to run the ESP32 itself. The controller board holds the microcontroller, a Neopixel as a status indicator, and a pair of buttons — one for switching the lights on and off, the other for resetting to default settings. The physical housing is 3D printed, and looks great with the glowing status indicator in the middle of the switch.

[Brian]’s switches are triggerable via MQTT, a web interface, and the physical button onboard the device itself. Having built the devices on his own, he’ll be well-placed to troubleshoot any usability or reliability issues that crop up in the future. That’s a lot more than we can say about most smart devices on the market!

USB Borescope Lets Doctors Hone Intubation Skills On The Cheap

April 30, 2023 by 8 Comments

One of the most critical skills in emergency medicine is airway management. Without a patent airway, a patient has about four minutes to live, so doctors and paramedics put a huge amount of effort into honing their intubation skills. They have to be able to insert an endotracheal tube quickly and efficiently, without damaging sensitive structures like the vocal cords. It’s a tricky skill to master without a ton of practice.

The perfect tool to practice these skills is a video laryngoscope, but these are wildly expensive and reserved for clinical use. Luckily, with a little ingenuity and a cheap USB borescope, [Dr. Adam Blumenberg] and [Dr. Erin Falk] were able to come up with this low-cost video-assisted laryngoscopy setup to reach as many students as possible. The idea is to use a single-use laryngoscope blade, which replicates the usual tool used to visualize the patient’s vocal cords. The blade is made from clear plastic, which makes it perfect for the application. The borescope is passed through an opening in the blade and affixed to it with adhesives. A little Dremel work might be necessary to get the optical axes of the blade and the camera to line up; failing that, there’s always the option to disassemble the camera to get a better angle.

The chief advantage of this setup, aside from being cheap, is that it’s something that it’s not intended to be used on patients. Along with an airway manikin, the tricked-out borescope can sit in a conference room waiting for students to have a go. Using a large screen allows the whole group to watch the delicate procedure and learn from the mistakes of others. It may not be as detailed a simulation environment as some, but “blade time” is really what counts here.

RP2040 Gets Intellikeys Keyboard Up And Running

April 29, 2023 by 7 Comments

The Spectronic Intellikeys was an innovative keyboard-like accessibility device that used special plastic overlays that change its functionality. While a USB version of the accessible keyboard exists, it doesn’t work like a normal HID device, so it’s not plug and play as you might expect. It’s also no longer in production or supported by the manufacturer. Where industry falls down, the community steps in, right? To that end, Adafruit has built a tool for interfacing with these useful accessibility devices.

The key is the way the Intellikeys was intended to work with a computer. It was designed to download its firmware from the host machine, using special drivers that are only compatible with certain versions of Windows. That means you can’t use it with iPads or Chromebooks, for example.

To get around this, Adafruit used an RP2040 Feather configured as a USB host to talk to the Intellikeys. It queries the device, determines which overlay it currently has installed, and provides it the necessary firmware. On the other end, the Feather enumerates as a regular USB HID device. That allows it to work with a wide variety of tablets, computers, and even smartphones.

If you’ve got an Intellikeys USB device and miss using it, this could be just the thing you need. Meanwhile, you can check out some of the other interesting keyboard designs we’ve featured over the years.

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Don’t Let The Baluns Float Over Your Head

April 29, 2023 by 5 Comments

Most ham radio operators will build an antenna of some sort when they first start listening or transmitting, whether it’s a simple dipole, a beam antenna like a Yagi, or even just a random wire vertical antenna. All of these will need to be connected feedline of some sort, and in the likely event you reach for some 50-ohm coax cable you’ll also need a balun to reduce noise or unwanted radiation. Don’t be afraid of extra expenses when getting into this hobby, though, as [W6NBC] demonstrates how to construct an “ugly balun” out of the coax wire itself (PDF).

The main purpose of a balun, a contraction of “balanced-unbalanced” is to convert an unbalanced transmission line to a balanced one. However, as [W6NBC] explains, this explanation obscures much of what baluns are actually doing. In reality, they take a three-wire system (the coax) and convert it to a two-wire system (the antenna), which keeps all of the electrical noise and current on the shield wire of the coax from interfering with the desirable RF on the interior of the coax.

This might seem somewhat confusing on the surface, as coax wires only have a center conductor and a shield wire, but thanks to the skin effect which drives currents to the outside of the conductor, the shield wire effectively becomes two conductors when taking into account its inner and outer surfaces. At these high frequencies the balun is acting as a choke which keeps these two high-frequency conductors separate from one another, and keeps all the noise on the outside of the shield wire and out of the transmitter or receiver.

Granted, the world of high-frequency radio circuits can get quite complex and counter-intuitive and, as we’ve shown before, can behave quite unexpectedly when compared to DC or even mains-frequency AC. But a proper understanding of baluns and other types of transformers and the ways they interact with RF can be a powerful tool to have. We’eve even seen other hams use specialty transformers like these to make antennas out of random lengths and shapes of wire.

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