Photochromic Dye Makes Up This Novel Optical Memristor

Despite being much in the zeitgeist lately, we have to confess to still being a bit foggy about exactly what memristors are. The “mem” part of their name seems to be the important bit, implying a memory function, but the rest of the definition seems somewhat negotiable — enough so that you can make a memristor from a bit of photochromic dye.

Now, we’ll leave the discussion of whether [Markus Bindhammer]’s rather complex optical memory cell officially counts as a memristor to the comments below, and just go through the technical details here. The heart of this experimental device is a photochromic dye known as cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene, mercifully shortened to CMTE, which has the useful property of having two stable states. Transitioning from the open state to the closed state occurs when UV light shines upon it, while switching back to the closed state is accomplished with a pulse of green light. Absent the proper wavelength of light, both states are stable, making non-volatile information storage possible.

To accomplish this trick, [Markus] filled a quartz cuvette with a little CMTE-doped epoxy resin. Inside a light-tight enclosure, two lasers — one at 405 nm wavelength, the other at 532 nm — are trained on the cuvette through a dichroic mirror. On the other side of the CMTE resin, he placed a VEML7700 high-accuracy ambient light sensor. An Arduino Nano reads the light sensor and controls the lasers. Writing and erasing are accomplished by turning on the proper laser for a short amount of time; reading the state of the cell involves a carefully timed pulse from the 405 nm laser followed by a 532 nm pulse and watching the output of the sensor.

Is a one-bit memory device that uses a dye that goes for €300 per gram and a pair of laser diodes practical? Of course not, but it’s still pretty cool, and we appreciate all the effort and expense [Markus] went to with this one. Now, if you want some fuel for the “It’s not a memristor” fire, memristors might not even be a thing.

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Hack On Self: The Alt-Tab Annihilator

Last time, I told you about a simple script I made to collect data about my laptop activity, talked about why collecting data about yourself is a moral imperative, and shared the upgraded script with you alongside my plans for it. Today, I will show you a problem I’ve been tackling, with help of this script and the data it gives, and I also would love to hear your advice on a particular high-level problem I’m facing.

Today’s problem is as old as time – I often can’t focus on tasks I badly need done, even ones I want done for myself. This has been a consistent problem in my life, closing off opportunities, getting me to inadvertently betray my friends and family, hurting my health and well-being, reinforcing a certain sort of learned helplessness, and likely reinforcing itself as it goes, too.

It’s deeply disturbing to sit down fully intending to work on a project, then notice no progress on it hours later, and come to a gut-wrenching realization you’ve had hundreds of such days before – I think this screws with you, on a fundamental level. Over the years, I’ve been squeezing out lessons from this failure mode, making observations, trying out all sorts of advice, in search of a solution.

Join me today in non-invasive brain augmentation and reprogramming, as I continue trying to turn my life around – this time, with help of my laptop, a computer that I already spend a ton of time interfacing with. Ever notice that starting work on a task  is often the hardest part of it? It’s the same for me, and I decided to hack away at it.

Staying On Track

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Vehicle-To-Everything: The Looming Smart Traffic Experience

Much of a car’s interaction with the world around it is still a very stand-alone, analog experience, regardless of whether said car has a human driver or a self-driving computer system. Mark I eyeballs or equivalent computer-connected sensors perceive the world, including road markings, traffic signs and the locations of other road traffic. This information is processed and the car’s speed and trajectory are adjusted to ideally follow the traffic rules and avoid unpleasant conversations with police officers, insurance companies, and/or worse.

An idea that has been kicked around for a few years now has been to use wireless communication between cars and their environment to present this information more directly, including road and traffic conditions, independent from signs placed near or on the road. It would also enable vehicle-to-vehicle communication (V2V), which somewhat like the transponders in airplanes would give cars and other vehicles awareness of where other traffic is hanging out. Other than V2V, Vehicle-to-Everything (V2X) would also include communication regarding infrastructure (V2I), pedestrians (V2P) and an expansive vehicle-to-network (V2N) that gives off strong Ghost in the Shell vibes.

Is this is the future of road traffic? The US Department of Transport (DOT) seems to think that its deployment will be a good thing, but V2X has been stuck in regulatory hurdles. This may now change, with the DOT releasing a roadmap for its deployment.

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Towards Solderless PCB Prototyping

When we think of assembling a PCB, we’re almost always thinking about solder. Whether in paste form or on the spool, hand-iron or reflow, some molten metal is usually in the cards. [Stephen Hawes] is looking for a solderless alternative for prototyping, and he shows us the progress he’s made toward going solderless in this video.

His ulterior motive? He’s the designer of the LumenPNP open-source pick-and-place machine, and is toying with the idea of a full assembly based just on this one machine. If you strapped a conductive-glue extruder head on the machine in addition to the parts placer, you’d have a full assembly in one step. But we’re getting ahead of ourselves.

[Stephen] first tries Z-tape, which is really cool stuff. Small deformable metal balls are embedded in a gel-like tape, and conduct in only the Z direction when parts are pushed down hard into the tape. But Z-tape is very expensive, requires a bit of force to work reliably, and [Stephen] finds that the circuits are intermittent. In short, Z-tape is not a good fit for the PNP machine.

But what [Stephen] does find works well is a graphite-based conductive glue. In particular, he likes the Bare Conductive paint. He tries another carbon-based paint, but it’s so runny that application is difficult, while the Bare stuff is thick and sticky. (They won’t tell you their secret formula, but it’s no secret how the stuff is basically made.) That ends up looking very promising, but it’s still pretty spendy, and [Stephen] is looking to make his own conductive paste/paint pretty soon. That’s particularly appealing, because he can control the stickiness and viscosity, and he’ll surely let us in on the secret sauce.

(We’re armchair quarterbacking here, but the addition of a small amount of methyl cellulose and xanthan gum works to turn metal powder into a formable, printable metal clay, so it might make a carbon paste similarly adjustably sticky.)

We love the end-goal here: one machine that can apply a conductive paint and then put the parts into the right place, resulting in a rough-and-ready, but completely hands-off assembly. You probably wouldn’t want to use this technique if the joint resistance was critical, or if you needed the PCB to stand up to abuse. There’s a reason that everyone in industry uses molten metal, after all. But for verifying a quick one-off, or in a rapid-prototyping environment? This would be a dream.

We’ve seen other wacky ways to go solderless before. This one uses laser-cut parts to hold the components on the PCB, for instance. And for simply joining a couple wires together, we have many more solutions, many thanks to you all in the comments!

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Hackaday Links: October 6, 2024

Remember that time a giant cylindrical aquarium in a Berlin hotel bar catastrophically failed and left thousands of fish homeless? We sure do, and further recall that at the time, we were very curious about the engineering details of how this structure failed so spectacularly. At the time, we were sure there’d be plenty of follow-up on that score, but life happened and we forgot all about the story. Luckily, a faithful reader named Craig didn’t, and he helpfully ran down a few follow-up articles that came out last year that are worth looking at.

The first is from prosecutors in Berlin with a report offering three possibilities: that the adhesive holding together the acrylic panels of the aquarium failed; that the base of the tank was dented during recent refurbishment; or that the aquarium was refilled too soon after the repairs, leading to the acrylic panels drying out. We’re a little confused by that last one just from an intuitive standpoint, but each of these possibilities seems hand-wavy enough that the report’s executive summary could have been “Meh, Scheiße happens.”

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A Japanese-input macro pad with a display and color-coded light-up keys.

Introducing The KanaChord Plus Keyboard カナコード・プラス・キーボード

We love to watch your projects grow as much as you do. Really, we’re like proud grandparents around here. So it’s great to see that [Mac Cody] is back with the KanaChord Plus Keyboard, which supports an astounding 6,165 Kanji as well as 6,240 of the most common Japanese words that contain Kanji. This is all in addition to supporting the Kana characters, which make up the rest of Japanese writing (more on that in a minute).

If you need to input Japanese, this is a dream come true. If you’re trying to learn Japanese in the first place, this could be exactly what you need to become fluent.

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