Dear all,

    I have a structure that can only be fabricated with SU-8 in a positive
manner (that is, my SU-8 structure is the same as my final structure, instead of
being a negative as in most SU-8 mold fabrication). But I do need to have this
structure in PDMS. So my plan is to do regular PDMS molding using the SU-8
structure and get a negative PDMS mold. With the negative mold and a second PDMS
molding process, I should have a PDMS structure same as the original SU-8 one.
Has anyone done something like this before? How did you overcome the PDMS to
PDMS sticking problem? I am thinking about surface silanization on the PDMS
negative mold, however is concerning about how well the silanization can be done
on PDMS surface and how long it can last. So if anyone has previous experience
with similar procedure, please give some advice about if this is doable or not
(I do have high aspect ratio structure, 10um wide, 100um tall). Or, is there any
other material that I use to make a negative mold from SU-8 master so the
following PDMS mold maybe easy on that material?

    Any input is greatly appreciated and thx in advance.

Guocheng Shao