--- Log opened Sun May 09 00:00:49 2021
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01:48 < juri_> lsneff: indeed. not enough people doing stuff. :P
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10:17 < lsneff> http://www.gaudi.ch/OpenDrop/
10:17 < lsneff> Super interesting
10:18 < lsneff> It seems like this shouldn’t be too difficult to scale up to boards with a million cells
10:21 < lsneff> Yeah wow, this is fascinating
10:22 < lsneff> I wonder if I can get involved
11:18 < fenn> lsneff: didn't we already go over this? https://en.wikipedia.org/wiki/Optoelectrowetting#Single-sided_continuous_optoelectrowetting_(SCOEW)
11:30 < lsneff> I don't remember doing so
11:33 < lsneff> So, how can you do optoelectrowetting? Coating an lcd?
11:39 < fenn> that was my plan
11:40 < fenn> at worst you could use a projector and reducing lens
12:18 < lsneff> have you tried it?
12:36 < kanzure> https://www.bizjournals.com/boston/news/2021/05/06/george-church-founded-gene-therapy-startup-gets-1.html
12:36 < kanzure> lsneff: search logs for electrowetting
12:37 < kanzure> or in here https://diyhpl.us/~bryan/papers2/microfluidics/
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18:04 < lsneff> hmm
18:07 < lsneff> It does seem like the coatings are simpler in the case of regular electrowetting, but I've only got through a few papers about it so far.
18:07 < lsneff> fenn: what's your plan for synthesizing the surfaces?
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18:21 < lsneff> The one downside of optoelectrowetting I can think of is that it's probably more difficult to add heating functionality to independent cells
18:24 < fenn> i thought it was something reasonably off the shelf, like a sheet of transparent plastic with ITO deposited on one side
18:26 < fenn> the paper is in diyhpl.us/~bryan/papers2/microfluidics/ and they explain how to make the coatings in section 2
18:26 < fenn> Single-sided ... SCOEW ... 2010.pdf
18:29 < kanzure> https://www.zerohedge.com/political/derby-drug-bust-thoroughbred-roids-could-see-victory-revoked
18:30 < fenn> hm i guess specifically amorphous silicon is needed to convert light into electrical potential
18:31 < fenn> so you'd need to sputter it or do some kind of silane hydrogen bake out
18:32 < lsneff> "The device consists of a glass substrate coated witha 0.5 mm thick featureless hydrogenated amorphous silicon(a-Si:H) layer. Two 0.1 mm thick strip aluminium (Al) electrodesseparated by a 5 cm gap are deposited at two ends of this device,and a dc bias is applied to the two aluminium electrodes toprovide a lateral electric field across the entire SCOEW device.A1mm thick amorphous fluorocarbon polymer,
18:32 < lsneff> Cytop(CTL-809M), is spin-coated on the a-Si:H surface to providea hydrophobic dielectric layer. Aqueous droplets are positionedon top of the hydrophobic Cytop surface and immersed in oil."
18:33 < fenn> this is a bigger problem than i remembered, i guess i didn't understand something about how it worked before
18:35 < fenn> in order to use a LCD you'd need a very thin film with a photovoltaic substance coated on one side
18:36 < fenn> or at least something that changes resistance in response to light
18:37 < lsneff> could a sheet of amorphous silicon be pulled out of cheap solar panels?
18:38 < lsneff> or does it have to be transparent
18:38 < fenn> there's been some developments of simple water based perovskite deposition reactions in the intervening decade
18:38 < fenn> i don't think it has to be transparent, but it does have to be thinner than the pixel pitch
18:41 < lsneff> Isn't there some way to spray solar panels onto flat surfaces? Thin-film, etc
18:41 < lsneff> could that process be taken advantage of?
18:43 < fenn> yes it's done by sputtering in a vacuum chamber
18:44 < fenn> there's a whole field of physical vapor deposition and it's mostly voodoo as far as i can tell
18:44 < fenn> do look up perovskites as they should be much easier and cheaper to do
18:44 < fenn> you only need a photoresistor, not photovoltaic
18:47 < lsneff> do you have a link to a paper?
18:47 < fenn> no
18:48 < fenn> i haven't kept up with the field of perovskite solar cells since they were first discovered
18:49 < fenn> i only say "solar cells" because i can't think of a better word, but there's a whole array of magic crystals
18:49 < fenn> and many of them can be made with kitchen chemistry
18:50 < fenn> alternatively, maybe you can just buy photoresistor film
18:51 < fenn> (not "photoresist film")
18:54 < fenn> CdS photoresistors are made with cadmium sulfate, thiourea, and ammonium sulfate
18:55 < fenn> the problem is that depositing a relatively thick brittle film on a thin flexible substrate usually leads to the film flaking off
18:56 < fenn> in order to do contact optics (no lenses, just laminate to the front of an LCD) the substrate must be less than the pixel size
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18:57 < fenn> otherwise the pixels will blur as you get farther from the LCD surface
19:00 < gradstudentbot> That's the control group, right?
19:01 < lsneff> thankfully, this won't be a flexible substrate
19:02 < fenn> well i'm implicitly adding the constraint that there is a large number of pixels
19:02 < lsneff> also, is there any rhyme or reason for when that vkt goes off
19:02 < lsneff> Indeed
19:02 < fenn> the "gigaprinter" was supposed to do a billion base pairs in a single run or something like that
19:03 < fenn> in order to combine them into a single sequence we needed something like an iPad LCD which has a pretty high pixel density
19:04 < lsneff> That being said, even a high definition display has pixels that are something on the order of 0.1 mm per side
19:05 < lsneff> Which sounds pretty thick for a thin film
19:06 < fenn> another problem i just thought of: the large applied voltage to get the SCOEW to work might interfere with the active matrix electronics inside the LCD
19:06 < fenn> you don't typically put large high voltage electrode sheets on your LCD and expect it to still work
19:07 < fenn> it's in the tens of volts at least
19:08 < fenn> irritating lack of detail in the paper. they could have easily said how many volts were applied
19:10 < fenn> or what type of LCD it was
19:10 < fenn> or how thick the amorphous silicon layer was
19:10 < fenn> etc.
19:11 < lsneff> It's protection against people continuing their work, ironically
19:11 < fenn> reproducibility? what's that?
19:11 < lsneff> I have no idea how sensitive LCDs are to electric fields
19:13 < lsneff> I'm trying to think about whether the ability to selectively heat cells would be
19:13 < fenn> there's also OLED displays which have dense pixel pitch
19:13 < lsneff> Might be possible to do pcr on the surface if you can
19:13 < fenn> you can do that stuff from the other side with lasers
19:15 < lsneff> Sounds complicated
19:15 < fenn> btw why are you interested in this?
19:16 < fenn> for most operations there's an "ASIC" style chip made out of channels etched into glass
19:16 < fenn> like for pcr you have a spiral that passes over hot and cold sectors
19:17 < lsneff> well, in this case, you could do that without specialized hardware
19:17 < lsneff> it just sounds interesting to me
19:18 < fenn> do you know about optical tweezers?
19:19 < fenn> kind of a similar idea but with solids instead of droplets
19:20 < lsneff> I've heard of those
19:20 < fenn> also a lot of phone cameras now use oil interface lenses for focusing
19:22 < lsneff> interesting
19:23 < fenn> the lens is filled with oil and water. the shape of the interface between them changes with applied voltage, and since they have a different refractive index, this changes the optical properties of the system
19:23 < fenn> it's cheap, compact, low power, and has no delicate parts to break
19:24 < fenn> and it can move rapidly
19:24 < fenn> i can't remember the buzzword now
19:29 < lsneff> is this a project you've actually considered doing?
19:29 < fenn> feasibility only
19:30 < fenn> bibliography here has some relevant stuff to the liquid camera lenses http://nature.com/articles/srep06378
19:30 < fenn> you don't _need_ the pressure gradient
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19:31 < fenn> i suck at optics though
19:33 < fenn> the gigaprinter gene synthesis platform was contingent on doing a demo reproducing POSAM in the counter culture lab, but that fell through due to no fume hood being available in the forseeable future
19:34 < fenn> it made heavy use of acetonitrile for washes and dispensing solvent
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19:34 < fenn> it would also be useful for rudimentary DNA data storage on tape
19:35 < fenn> you need the SCOEW to combine large numbers of individual oligos from the DNA printer in an automated fashion
19:36 < fenn> it would be great to just print on some thin polymer film with all the SCOEW stuff on it already, then pass that over the LCD to do the gene assembly while the printer prints the next section of tape
19:38 < fenn> glass plates and projectors and lenses would also work, it's just clunky and not elegant
19:42 < fenn> for maximum throughput you'd want ~100 print heads and a narrow ~1cm tape so the heads don't have to move at all, everything is done by droplet timing alone and fixed light patterns to combine the drops
19:42 < fenn> or instead of light patterns you could have a fixed geometry electrode to control the droplets
19:43 < fenn> no weird coatings needed that way, but you lose the general purpose hackability
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--- Log closed Mon May 10 00:00:50 2021