Hi,
I'm looking for a stiffer/stronger alternative to PDMS (10:1 mix kit) for microfluidic channel moulding. I've been making something similar to figure 1 here http://www.nature.com/nphys/journal/v6/n6/abs/nphys1637.html , but my barrier is quite narrow and thus sensitive to the flow.
I would still prefer it to be transparent... One alternative I've looked at is PC (http://pubs.rsc.org/en/content/articlehtml/2011/lc/c0lc00658k), but I'm working with 10-400um-scale devices so that probably wouldn't work!
Thanks for any suggestions!
Maybe try NOA81 UV resist, you can mold it from PDMS structure and then glue it on glass afteward.
Try polyurethane rubber. It is available in a wide variety of durometers. We have used Clear Flex from Smooth-On in the past but you may also want to look into medical grade polyurethane rubbers depending on the application.
How much stronger? The mechanical properties of PDMS can be adjust over quite a range while still keeping the 10:1 ratio - see open access paper here: http://iopscience.iop.org/0960-1317/24/3/035017/article
I have etched microfluidic channels out of silicon which can make very fine channels and is very rigid but not transparent as you requested. How about casting in PMMA? Or (as someone else suggested) different varieties of PDMS? Varieties ranging from very, very soft to very hard can be found - try NuSil materials (avaialble from http://www.silicone-polymers.co.uk here in UK)
Depending on your need you can etch glass the same way as you do with silicon. (there is this paper from the research group I work with...although is in spanish: Técnicas de Fabricación de Micro-Estructuras Metálicas de Cobre y Aluminio Sobre Sustratos de Vidrio y Silicio, Alberto Unigarro Calpa et al. 2015)... However the principle is the same as with silicon. O the other hand, you can use this fro casting: (Rapid prototyping of glass microfluidic chips Frederik Kotz et al.). Finally, I myself have used multiple methods for casting of microestructures, I have used Rubber silicon (as used for normal casting), different polyethilen resins, Gel coat (as used in boats an glass fiber composites), wax... mainly any casting material that goes from liquid to solid
Well, there are few alternatives but the bigger question is what is your application? PDMS is not a particularly great material but it does many things well. It is optically transparent (to a certain extent) but many glass and glass like materials are still better. If optical transparency is what you need then go with etching glass (wet etching is pretty cheap but a bit dangerous) or quartz can be laser etched. Silica is a great material if you have the equipment to etch silica and the oxidized top layer.
If you are growing cells, PMMA is a great option and it still maintain some optical transparency.
If you want a gel-like material then you can use agarose (I have used it but it is messy). You can use poly styrene or poly ethylene but you may have to do a lot of heating or using a solvent which dissolves them well.
Some researchers do hot embossing of PMMA. You could also make mess-scale devices (mm scale) using double-sided scotch tape.
Good luck with your project!
OK,
Well, if the stiffness is the only concern you have, Youngs Modulus of PDMS can be altered by using different ratios of monomers to curing agent. To go stiffer, add more curing agent and mix longer then use a vacuum chamber to remove the bubbles.
Alternatively, PMMA is a stiff as it gets and it is transparent. You will have to use hot embossing to make the features you suggested. However, this can be done relatively easily.
Good luck.
PMMA would be an excellent way to go. If you can make a mould, it can be cast, like you would a PDMS version. Alternatively a solid piece can be CNC machined (to sub-micron-scale accuracy these days with the right tools) or laser-micromachined or (as Marion suggested) hot embossed.
Flexdym is a great alternative to PDMS, which saves you time and money.
The fabrication protocol is easy to use and only 2-15 minutes long, depending on your application. And because Flexdym is a thermoplastic, it can be recycled and re-molded. Check it out at https://eden-microfluidics.com/
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