Memristors Are Cool, Radiation-resistant Memristors Even Moreso

October 5, 2024 by Donald Papp 9 Comments

Space is a challenging environment for semiconductors, but researchers have shown that a specific type of memristor (the hafnium oxide memristor, to be exact) actually reacts quite usefully when exposed to gamma radiation. In fact, it’s even able to leverage this behavior as a way to measure radiation exposure. In essence, it’s able to act as both memory and a sensor.

Being able to resist radiation exposure is highly desirable for space applications. Efficient ways to measure radiation exposure are just as valuable. The hafnium oxide memristor looks like it might be able to do both, but before going into how that works, let’s take a moment for a memristor refresher.

A memristor is essentially two conductive plates between which bridges can be made by applying a voltage to “write” to the device, by which one sets it to a particular resistance. A positive voltage causes bridging to occur between the two ends, lowering the device’s resistance, and a negative voltage reverses the process, increasing the resistance. The exact formulation of a memristor can vary. The memristor was conceived in the 1970s by Leon Chua, and HP Labs created a working one in 2008. An (expensive) 16-pin DIP was first made available in 2015.

A hafnium oxide memristor is a bit different. Normally it would be write-once, meaning a negative voltage does not reset the device, but researchers discovered that exposing it to gamma radiation appears to weaken the bridging, allowing a negative voltage to reset the device as expected. Exposure to radiation also caused a higher voltage to be required to set the memristor; a behavior researchers were able to leverage into using the memristor to measure radiation exposure. Given time, a hafnium oxide memristor exposed to radiation, causing it to require higher-than-normal voltages to be “set”, eventually lost this attribute. After 30 days, the exposed memristors appeared to recover completely from the effects of radiation exposure and no longer required an elevated voltage for writing. This is the behavior the article refers to as “self-healing”.

The research paper has all the details, and it’s interesting to see new things relating to memristors. After all, when it comes to electronic components it’s been quite a long time since we’ve seen something genuinely new.

Retrotechtacular: The Other Kind Of Fallout Show

April 16, 2024 by Dan Maloney 29 Comments

Thanks to the newly released Amazon Prime series, not to mention nearly 30 years as a wildly successful gaming franchise, Fallout is very much in the zeitgeist these days. But before all that, small-F fallout was on the minds of people living in countries on both sides of the Iron Curtain who would have to deal with the aftermath of a nuclear exchange.

“Uwaga! Pył promieniotwórczy“ (“Beware! Radioactive Dust”) is a 1965 Polish civil defense film from film studio Wytwórnia Filmów Oświatowych. While the Cold War turning hot was not likely to leave any corner of the planet unscathed, Poland was certainly destined to bear the early brunt of a nuclear exchange between the superpowers, and it was clear that the powers that be wanted to equip any surviving Polish people with the tools needed to deal with their sudden change in circumstances.

The film, narrated in Polish but with subtitles in English, seems mainly aimed at rural populations and is mercifully free of the details of both fallout formation and the potential effects of contact with radioactive dust, save for a couple of shots of what looks like a pretty mild case of cutaneous radiation syndrome.

Defense against fallout seems focused on not inhaling radioactive dust with either respirators or expedient facemasks, and keeping particles outside the house by wearing raincoats and boots, which can be easily cleaned with water. The fact that nowhere in the film is it mentioned that getting fallout on your clothes or in your lungs could be largely avoided by not going outside is telling; farmers really can’t keep things running from the basement.

A lot of time in this brief film is dedicated to preventing food and water from becoming contaminated, and cleaning it off if it does happen to get exposed. We thought the little tin enclosures over the wells were quite clever, as were the ways to transfer water from the well to the house without picking up any contamination. The pros and cons of different foods are covered too — basically, canned foods dobry, boxed foods zły. So, thumbs up for Cram, but you might want to skip the YumYum deviled eggs.

Dealing with the potential for a nuclear apocalypse is necessarily an unpleasant subject, and it’s easy to dismiss the advice of the filmmakers as quaint and outdated, or just an attempt to give the Polish people a sense of false hope. And that may well be, but then again, giving people solid, practical steps they can take will at least give them some agency, and that’s rarely a bad thing.

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Mobile Phones And The Question Of Declining Sperm Quality

November 28, 2023 by Lewin Day 105 Comments

In a world increasingly reliant on technology, a pressing question arises: can our dependence on gadgets, particularly mobile phones, be affecting our health in unexpected ways? A growing body of research is now pointing towards a startling trend – declining sperm quality in the human population – with mobile phones emerging as a potential culprit.

Recent studies have been sounding the alarm over a noticeable decline in sperm counts and quality across the globe. This decline isn’t just about quantity; it’s about the vitality, motility, and overall health of sperm cells. The implications of this trend are profound, affecting fertility rates and possibly even the long-term viability of populations. The situation is murky and complicated, but new studies suggest that cellular phones could have a role to play.

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Radioactive Water Was Once A (Horrifying) Health Fad

November 10, 2023 by Donald Papp 25 Comments

Take a little time to watch the history of Radithor, a presentation by [Adam Blumenberg] into a quack medicine that was exactly what it said on the label: distilled water containing around 2 micrograms of radium in each bottle (yes, that’s a lot.) It’s fascinatingly well-researched, and goes into the technology and societal environment surrounding such a product, which helped play a starring role in the eventual Food, Drug, and Cosmetic Act of 1938. You can watch the whole presentation in the video, embedded below the break. Continue reading “Radioactive Water Was Once A (Horrifying) Health Fad” →

Hackaday Links: November 5, 2023

November 5, 2023 by Dan Maloney 5 Comments

As I write this, Supercon 2023 is in full swing down in Pasadena — 80 degrees and sunny at the moment, as opposed to 50 and pouring rain where I am, not that I’m bitter. Luckily, though, we can all follow along with the proceedings thanks to the livestreams on the Hackaday channel, which of course will all be available once they’re edited in case you miss anything live. There are a ton of interesting talks coming up, so there’ll be a lot to catch up on when the dust settles. And that won’t be far from now; by the time this post publishes, Supercon will be all but over, which makes it the Thanksgiving dinner of cons — all that work and it’s over in just a few minutes.

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DIY Repair Brings An X-Ray Microscope Back Into Focus

September 22, 2023 by Dan Maloney 6 Comments

Aside from idle curiosity, very few of us need to see inside chips and components to diagnose a circuit. But reverse engineering is another story; being able to see what lies beneath the inscrutable epoxy blobs that protect the silicon within is a vital capability, one that might justify the expense involved in procuring an X-ray imager. But what’s to be done when such an exotic and expensive — not to mention potentially deadly — machine breaks down? Obviously, you fix it yourself!

To be fair, [Shahriar]’s Faxitron MX-20 digital X-ray microscope was only a little wonky. It still generally worked, but just took a while to snap into the kind of sharp focus that he needs to really delve into the guts of a chip. This one problem was more than enough to justify tearing into the machine, but not without first reviewing the essentials of X-ray production — a subject that we’ve given a detailed look, too — to better understand the potential hazards of a DIY repair.

With that out of the way and with the machine completely powered down, [Shahriar] got down to the repair. The engineering of the instrument is pretty impressive, as it should be for something dealing with high voltage, heavy thermal loads, and ionizing radiation. The power supply board was an obvious place to start, since electrostatically focusing an X-ray beam depends on controlling the high voltage on the cathode cup. After confirming the high-voltage module was still working, [Shahriar] homed in on a potential culprit — a DIP reed relay.

Replacing that did the trick, enough so that he was able to image the bad component with the X-ray imager. The images are amazing; you can clearly see the dual magnetic reed switches, and the focus is so sharp you can make out the wire of the coil. There are a couple of other X-ray treats, so make sure you check them out in the video below.

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