SWIR sensors ideal for service robotics, automotive, consumer electronics sectors.
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Scientists make non-toxic quantum dots for shortwave infrared image sensors
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I should note that quantum-dot SWIR cameras are already on the market (https://www.swirvisionsystems.com/) though I don't know if they're lead-based. Still, for a single quantum dot layer it's far less total lead than the just the solder on the PCB would have had 20 years ago.
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I'm glad this technology is still advancing, and that it does not apparently include elements like the typical Cadmium, but these guys are WAY overpromising on the capabilities of shortwave infrared imaging.
SWIR typically cuts off at either 1.7um or 2.5um, depending on how you define it. These wavelengths are a little bit longer than visible wavelengths, but existing automotive microbolometer cameras already operate at ~10um (in LWIR). The primary advantage any of these have with atmospheric obscurants like dust, smoke, and fog come from imaging through particles that are smaller than the wavelengths they sense. Between 1-2.5um, the SWIR band isn't really gaining much benefit vs. visible/near-infrared.
The other big problem with typical quantum dot sensors is they are easily damaged by the sun. If you put one of these on a vehicle, it would need a shutter or strong filter during the day.
SWIR typically cuts off at either 1.7um or 2.5um, depending on how you define it. These wavelengths are a little bit longer than visible wavelengths, but existing automotive microbolometer cameras already operate at ~10um (in LWIR). The primary advantage any of these have with atmospheric obscurants like dust, smoke, and fog come from imaging through particles that are smaller than the wavelengths they sense. Between 1-2.5um, the SWIR band isn't really gaining much benefit vs. visible/near-infrared.
The other big problem with typical quantum dot sensors is they are easily damaged by the sun. If you put one of these on a vehicle, it would need a shutter or strong filter during the day.
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I don't think this is correct. I have worked in micro-optics and photonics for quite a bit. SWIR, MWIR, ect are expensive because they rely on other than silicon for the light sensitive materials. ROICS, (Read Out Integrated Circuits) are all silicon based, as is most of the semiconductor industry. Equipment and processes for silicon are much much more affordable compared to other material systems because they are so widely used. Fabrication of semiconductor components that rely on materials other that silicon is a primary reason of increases cost, NOT toxicity of the materials used. All of these micro fabrication methods use MANY very toxic chemicals.
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As non-toxic materials go tellurium is pretty toxic … notoriously, ingesting tellurium gives you worse-than-garlic breath that lasts for months; http://wavefunction.fieldofscience.com/2015/06/how-linus-pauling-almost-gave-matt.html
Not sure how stable Ag2Te would be to hydrolysis in an acid environment
Not sure how stable Ag2Te would be to hydrolysis in an acid environment
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The article says "In 2013, German physicists built the experimental equivalent of Maxwell's demon with a pair of interacting quantum dots"
However, the linked Scientific American article explicitly says the researchers did not build it. From the linked article --
ETA, "I haven't actually built it, but I'm optimistic it'll work" is a very researcher-y thing to say. Just give me some more funding boss, and a couple of grad students.
However, the linked Scientific American article explicitly says the researchers did not build it. From the linked article --
ETA, "I haven't actually built it, but I'm optimistic it'll work" is a very researcher-y thing to say. Just give me some more funding boss, and a couple of grad students.
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Next up, Maxwell's demon uses silver hammer to create quantum dot-matrix printer...
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I wonder if this is like those cameras that came out quite a while back that can use IR to view underneath bathing suits. Maybe this will do a better job?
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Photon_plumber
Ars Tribunus Militum
Quantum dots. The toxic material usage is only half the issue we were worried about at the time during our research. The other was the size of particles we were utilizing in the lab. They're small enough to slip through the blood-brain barrier, and likely cause some as of yet unspecified medical issues. I have yet to hear of anyone who was accidentally exposed.
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Ars should write an article about QDEL screen technology currently being prototyped by Sharp. Quantum dots that directly take in electricity and convert it to light (no LCD layer and no backlight are involved). Seems to hold as much promise as microLED but without the manufacturing difficulties.
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I was wondering why lead and mercury seem to always be considered toxic? Other toxic elements seem to be rendered safe when in used in a compound. For instance, fluor is toxic, but fluoride in toothpaste is safe and beneficial.
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Miners in high tellurium mines (eg Telluride Colorado) used to get extra pay for "tellurium breath", as the local ladies of the night used to charge extra for their services.
Silver telluride is undoubtedly very stable to hydrolysis, as all of the silver chalconides are extraordinarily insoluble, and I would expect that in service they would never see the kind of drastically acidic conditions which would be needed for hydrolysis to be problem. What I would worry about is oxidation of the telluride to tellurate, with silver, which can have oxidation levels of 0, +1 +2 or +3 acting as a catalyst, especially if electric currents are also involved. Once the silver starts donating electrons to atmospheric oxygen, the microenvironment could become highly oxidizing, and then the telluride will start being oxidized by peroxide radicals.
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The silver in silver telluride is already oxidized (+1), so I'm not sure this is going to be much of a problem - it's not going to be donating electrons at that point.
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I think you have reassured me; the higher oxidation levels of silver tend to require heroic conditions (the preparation for KAgF4 has 'heat to 400C in a sealed container pressurised with fluorine gas for 24 hours' to get to +3, +2 merely requires treating Ag2O with elemental fluorine).
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Heroic or insane conditions - it's a close call. (I'll add it to my collection of things that go FOOF!)
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