NeverWet Spray-on superhydrophobic coat for "mini"-fluidics
107 views
Skip to first unread message
Luis Zaman
Dec 20, 2013, 4:35:54 PM12/20/13
to diy...@googlegroups.com
I'm fairly new to the DIY Bio stuff, and I'm incredibly new to micro/mini fluidics, but I wanted to share something that might be of use to the community. I picked up some "Rustoleum NeverWet" from the local hardware store and sprayed it on a few microscope slides to see what I could do with it. I tried taping off small regions, but the coat just peels off when I try to remove them. Just cutting out some shapes with a razor blade and another slide to make a clean edge worked nicely, probably because it is so easy to peel off. Here are a couple of pictures showing the resulting slide. I'm hoping this is useful, perhaps when sandwiched together?
Luis
Avery louie
Dec 20, 2013, 5:55:47 PM12/20/13
to diy...@googlegroups.com
The reason you have to cut it is because the basecoat makes a thin polymer layer for the hydrophobic layer to assemble on. This layer is continuous so you can tear it up. It also has pretty crappy chemical resistance, iirc. I think it has to do with poor basecoat adhesion.
--A
On Dec 20, 2013 5:06 PM, "Luis Zaman" <luis....@gmail.com> wrote:
I'm fairly new to the DIY Bio stuff, and I'm incredibly new to micro/mini fluidics, but I wanted to share something that might be of use to the community. I picked up some "Rustoleum NeverWet" from the local hardware store and sprayed it on a few microscope slides to see what I could do with it. I tried taping off small regions, but the coat just peels off when I try to remove them. Just cutting out some shapes with a razor blade and another slide to make a clean edge worked nicely, probably because it is so easy to peel off. Here are a couple of pictures showing the resulting slide. I'm hoping this is useful, perhaps when sandwiched together?Luis
--
-- You received this message because you are subscribed to the Google Groups DIYbio group. To post to this group, send email to diy...@googlegroups.com. To unsubscribe from this group, send email to diybio+un...@googlegroups.com. For more options, visit this group at https://groups.google.com/d/forum/diybio?hl=en
Learn more at www.diybio.org
---
You received this message because you are subscribed to the Google Groups "DIYbio" group.
To unsubscribe from this group and stop receiving emails from it, send an email to diybio+un...@googlegroups.com.
To post to this group, send email to diy...@googlegroups.com.
Visit this group at http://groups.google.com/group/diybio.
To view this discussion on the web visit https://groups.google.com/d/msgid/diybio/5fb1f376-4246-43ef-bd48-b68d4f9a688b%40googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.
Luis Zaman
Dec 20, 2013, 11:21:18 PM12/20/13
to diy...@googlegroups.com
I'm not sure about the chemical resistance, I'm sure it's not great. It did hold up to a standard 80% ethanol surface sterilization though, which is probably good enough for what I would be doing with it. Seems autoclaving wouldn't be a good idea... I would love an optically clear superhydrophobic coating for continuous culture devices, but so far it seems like thats only being produced in nano research labs.
Luis
Avery louie
Dec 20, 2013, 11:55:01 PM12/20/13
to diy...@googlegroups.com
Try rainx
To view this discussion on the web visit https://groups.google.com/d/msgid/diybio/f93eb186-34c6-4e99-a848-101dce00409d%40googlegroups.com.
Luis Zaman
Dec 21, 2013, 12:14:10 AM12/21/13
to diy...@googlegroups.com
Interesting, any experience autoclaving RainX treated glassware? Would be amazing if I could avoid biofilms from forming in chemostats with a little bottle of rainx!
Luis
You received this message because you are subscribed to a topic in the Google Groups "DIYbio" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/diybio/rqOC4cAySdM/unsubscribe.
To unsubscribe from this group and all its topics, send an email to diybio+un...@googlegroups.com.
To post to this group, send email to diy...@googlegroups.com.
Visit this group at http://groups.google.com/group/diybio.
To view this discussion on the web visit https://groups.google.com/d/msgid/diybio/CAL4KOmgucjT%2Bea3WCYo2BXoqp6nmj4rw%2BAodgsFbv7HRsZGv2w%40mail.gmail.com.
Avery louie
Dec 21, 2013, 12:17:40 AM12/21/13
to diy...@googlegroups.com
Mm...rainx is some kind of pdms or something- give it a try. Iirc it bonds to glass pretty well, and it should be food up to atleast 120c.
To view this discussion on the web visit https://groups.google.com/d/msgid/diybio/381164613D97406F854F144D2D9448EC%40gmail.com.
Luis Zaman
Dec 21, 2013, 12:20:24 AM12/21/13
to diy...@googlegroups.com
Will definitely try it out, we use it in the lab already to keep condensation from causing optical problems. Haven’t tried autoclaving it though.
To view this discussion on the web visit https://groups.google.com/d/msgid/diybio/CAL4KOmiJRc2st7yPNgP0B8y6Joih%2BpvNdPzJ0qeRMe2z0QDaJQ%40mail.gmail.com.
Jonathan Cline
Dec 21, 2013, 1:09:33 AM12/21/13
to diy...@googlegroups.com, jcline
Hello
Others mentioned Rain-x too. I used Rain-x as it was written as a published protocol in Lab On A Chip journal. (That journal might also be called the "'We'll publish near anything as long as it's slightly mentionable in Wired' Journal".) Deep in the supplementary notes for a few microfluidics experiments are references to Rain-X. Gee, wonder why that wasn't part of the abstract? Are postdocs afraid of mentioning a common auto-parts store product as the core of their experimental results? 8-D Certainly the P.I.'s jaw hit the floor when I finally mentioned what coating worked best in my experiments (I also tried some polymer thin films which didn't work as well).
Anyway,
The basic idea is to drop/spray/spin some quantity of Rain-x on glass or whatever surface you like. I used FR4 printed circuit board since I was doing electrowetting experiments which had copper traces pre-etched on the boards. Then you bake the coated substrate at a certain time & temp. I used my kitchen oven. It worked to some degree (no pun intended). Pics on my blog http://88proof.com/synthetic_biology/blog/archives/tag/microfluidics
Another alternative (also in the publications) is to paint saran-wrap (a good & cheap film-over-substrate) with the coating of choice. You can cut out the patterns of saran-wrap ahead of time with your desired channel pattern (positive image), paint them, then carefully place the film on your substrate, then bake at temp. The saran wrap will melt to the substrate at the right temp. I think doing a negative image as a resist for the coating would be really tough, or doing the paint-then-cut-out, like you describe, would also be tough.
Maybe you could try putting the coating liquid (i.e. rain-x) in an inkjet printer head and spraying it on your substrate (i.e. print out the desired positive of the channel image). Not sure if the nanoparticle stuff would print through an inkjet printer or not. Rain-x might spray but it also might clog the inkjet heads too.
As you suggest, once the coating gets chemically dirty, the substrate becomes sticky and the chip is toast. But you might try an emulsion on top of the substrate, i.e. do your experiment in water-in-oil; then the substrate is coated & washed in oil so it's more likely to remain usable for longer. Then the "is the coating compatible?" question may be less important. I thought I heard that the nano coatings fail in the presence of salts (maybe that's hearsay, just something I remember from somewhere, or maybe a lot of washing is required). One problem I encountered (with the electrowetting) was arcing due to high voltage, somewhat due to imperfections in the chips or for whatever reason, which would leave deposits on the chips thus destroy the coating.
What would be interesting now, since 3D printers have reached good enough resolution (sub-0.5mm), is to print chips-with-fluid-channels on demand, clean them, spray them with the hydrophobic coating, then use. By coating the channels, or maybe only certain channels, the flow of the reagents might get interesting (better mixing? or control flows across certain temp zones?). If you find a compatible plastic to print with, then running the chips through the dishwasher then an autoclave step then recoat might recycle them a few times.
Others mentioned Rain-x too. I used Rain-x as it was written as a published protocol in Lab On A Chip journal. (That journal might also be called the "'We'll publish near anything as long as it's slightly mentionable in Wired' Journal".) Deep in the supplementary notes for a few microfluidics experiments are references to Rain-X. Gee, wonder why that wasn't part of the abstract? Are postdocs afraid of mentioning a common auto-parts store product as the core of their experimental results? 8-D Certainly the P.I.'s jaw hit the floor when I finally mentioned what coating worked best in my experiments (I also tried some polymer thin films which didn't work as well).
Anyway,
The basic idea is to drop/spray/spin some quantity of Rain-x on glass or whatever surface you like. I used FR4 printed circuit board since I was doing electrowetting experiments which had copper traces pre-etched on the boards. Then you bake the coated substrate at a certain time & temp. I used my kitchen oven. It worked to some degree (no pun intended). Pics on my blog http://88proof.com/synthetic_biology/blog/archives/tag/microfluidics
Another alternative (also in the publications) is to paint saran-wrap (a good & cheap film-over-substrate) with the coating of choice. You can cut out the patterns of saran-wrap ahead of time with your desired channel pattern (positive image), paint them, then carefully place the film on your substrate, then bake at temp. The saran wrap will melt to the substrate at the right temp. I think doing a negative image as a resist for the coating would be really tough, or doing the paint-then-cut-out, like you describe, would also be tough.
Maybe you could try putting the coating liquid (i.e. rain-x) in an inkjet printer head and spraying it on your substrate (i.e. print out the desired positive of the channel image). Not sure if the nanoparticle stuff would print through an inkjet printer or not. Rain-x might spray but it also might clog the inkjet heads too.
As you suggest, once the coating gets chemically dirty, the substrate becomes sticky and the chip is toast. But you might try an emulsion on top of the substrate, i.e. do your experiment in water-in-oil; then the substrate is coated & washed in oil so it's more likely to remain usable for longer. Then the "is the coating compatible?" question may be less important. I thought I heard that the nano coatings fail in the presence of salts (maybe that's hearsay, just something I remember from somewhere, or maybe a lot of washing is required). One problem I encountered (with the electrowetting) was arcing due to high voltage, somewhat due to imperfections in the chips or for whatever reason, which would leave deposits on the chips thus destroy the coating.
What would be interesting now, since 3D printers have reached good enough resolution (sub-0.5mm), is to print chips-with-fluid-channels on demand, clean them, spray them with the hydrophobic coating, then use. By coating the channels, or maybe only certain channels, the flow of the reagents might get interesting (better mixing? or control flows across certain temp zones?). If you find a compatible plastic to print with, then running the chips through the dishwasher then an autoclave step then recoat might recycle them a few times.
-- ## Jonathan Cline ## jcl...@ieee.org ## Mobile: +1-805-617-0223 ########################
Nathan McCorkle
Dec 21, 2013, 5:11:00 AM12/21/13
to diy...@googlegroups.com
Also ozone or oxygen plasma pre-treatment is a good step prior to any bonding. An ionizer wind is better than nothing, but you can rig up an oxygen plasma bonder using a home microwave, vacuum pump, small oxygen cylinder, a section of 6 inch PVC pipe, gaskets, gas valves, and flat end pieces.
See this for a demo:
http://www.youtube.com/watch?v=N-R0_nXpc7I
You might also be able to use a fumed monolayer or thin-film of HMDS or FDTS, they can act as anti-stick and have pretty high contact angles (how hydrophobic coatings are often compared with each other).
interesting quote "Roughening a hydrophobic surface increases the effective contact angle" (also says Sandia has a formula that's $10/gal): http://www.ornl.gov/adm/partnerships/events/bridging_gap/presentations/Superhydrophobic_Materials.pdf
So basically I think they're attaching something cheap or fluoro/perfluoro-based and amplifying it via immense surface area of the fumed silica, pretty cool! I wonder if these guys are using the aerosil stuff... http://www.nbdnano.com/
Check out the fluoro compounds and superhydrophobic, I might end up trying some of the PERFLUORODECYL-1H,1H,2H,2H-DIMETHYLCHLOROSILANE ('FDTS', 5.0g/$36.00) as a release layer for my molds: http://www.gelest.com/goods/pdf/Hydrophobicity.pdf
And HMDS
http://www.2spi.com/catalog/chem/chem2a2.shtml
this pretty nice overview of the whole process starting with an exposed photoresist: http://diyhpl.us/~bryan/papers2/paperbot/Anti-stiction%20coating%20of% 20PDMS%20moulds%20for%20rapid% 20microchannel%20fabrication% 20by%20double%20replica%20moulding.pdf
--
-- You received this message because you are subscribed to the Google Groups DIYbio group. To post to this group, send email to diy...@googlegroups.com. To unsubscribe from this group, send email to diybio+un...@googlegroups.com. For more options, visit this group at https://groups.google.com/d/forum/diybio?hl=en
Learn more at www.diybio.org
---
You received this message because you are subscribed to the Google Groups "DIYbio" group.
To unsubscribe from this group and stop receiving emails from it, send an email to diybio+un...@googlegroups.com.
To post to this group, send email to diy...@googlegroups.com.
Visit this group at http://groups.google.com/group/diybio.
To view this discussion on the web visit https://groups.google.com/d/msgid/diybio/d9c3105a-cddb-4afc-840f-56e27beb9bc5%40googlegroups.com.
Reply all
Reply to author
Forward
0 new messages