I think I'll try picking up some PTFE sheets and machining them into
wafers before trying the previous methods, as all I'm really looking
for in the spin-coat substrate right now is that its flat and smooth.
If the PTFE isn't flat/smooth enough, then I'll revisit the FDTS or
other fluorination methods mentioned.

I do have some more questions about the FDTS while on the topic. I'm
guessing that the bake of 110 for 2 hours doesn't bond, rather it
enables adsorbtion by driving off water, is that correct? Also how
many times do you think the FDTS lasts, i.e. how many times can you
peel off without needing to reapply?

On Mon, Mar 29, 2010 at 12:05 PM, Kevin Paul Nichols
 wrote:
> Piranha will make things much worse. The PDMS isn't sticking to the
> wafers because they're dirty. Piranha will temporarily decrease the
> contact angle (the opposite of what you want).
>
> If biocompatibility is your primary concern, you can just dip-coat in
> a Teflon FEP emulsion (and bake), or spin-coat Teflon AF (and bake).
> Both of those will solve your problem, but they'll leave micron scale
> defects on the mold (dots in the case of FEP, or ripples, in the case
> of Teflon AF).
>
> If you're using PDMS microchannels in the standard way though, you
> don't need to worry about FDTS toxicity. When you plasma clean before
> bonding, you'll blast whatever unbonded FDTS residue might be there.
> There are 100's of papers out there where people culture cells in PDMS
> chips. There are biocompatibility issues with using PDMS (absorption
> of small molecules -- see Beebe's work -- water, etc) but toxicitiy of
> the mold release isn't one I've ever heard of.
>
> - Kevin

--
-Nathan McCorkle
---
Rochester Institute of Technology
College of Science, Biotechnology/Bioinformatics