Hi

I have a silicon wafer with SU-8 structures (pillars of 100 um - 400 um
diameter, 200um high). I cast PDMS around these structures, and finally, after
PDMS peel off,  would like to have fluid flowing through the resulting channels
in the PDMS. At present, in order to get an even top surface with the PDMS level
with the SU-8, I cast the PDMS and then use a thin polycarbonate sheet to
squeeze out excess PDMS and allow the sheet to lie on top of the SU-8 pillars.

The process works well in all aspects besides one. A thin membrane of PDMS
(probably about 10um) remains on top of the pillars. Presently I punch this
membrane to allow fluid flow, but this is not repeatable.

My question: is there an etch (or similar method) for removing PDMS, so that I
could etch the top 10um off my structure, thereby opening the channels?

Many thanks

Kevin