Hi! I’m just getting started with making a microfluidic chip and trying to gather materials. What supplier and product would you recommend for the Teflon coating, and what spin conditions?
I’m looking at Teflon AF 1600 from Sigma Aldrich dissolved to 1% wt/v in FC-40 solvent from Sigma Aldrich. I think someone else in my lab tried making Teflon AF 2400 to 6% wt/v and had trouble dissolving it.
A couple of studies have stated that spinning 1% Teflon AF 1600 in FC-40 at 3000 rpm gives a 200 nm thick coating. Another one says that spinning 1.2% Teflon AF at 2000 rpm gives a 50 nm coating, when one might expect (going by the first example) that it would be thicker than that. Has anyone measured actual film thicknesses? Is there a minimum thickness the hydrophobic layer should have? My understanding is that it is expected to break down under most standard actuation voltages.
Finally might anyone have recommendation for a cheaper hydrophobic coating that might be used?
Thanks a lot!!