Hi Matthew,

Matthew Davies wrote:
> I'm trying to create a regular array of 20 µm pillars of 40 µm height in
> PDMS by casting against an SU-8 master.  In one design the pillars are
> spaced 7.5 µm apart while in another they are spaced 25 µm apart.
>
> So far we have been unable to create good molds.  The holes are either:
> 1. ill-defined; 2. not full depth; or 3. tearing the PDMS pillars off.
[..]

Another problem might be air bubbles at the bottom of the SU-8 holes
so that the PDMS cannot enter further into the holes.
In this case you can try to apply vacuum to free the bubbles,
although I'm not sure this trick works for your dimensions, your
holes are rather small.

Or better - if you have the equipment - you cast the PDMS over
the SU-8 mold already in a vacuum chamber.

Good luck!

cu
Michi

--
Michael Riss
Parc Científic de B., Ed. Helix, IBEC
Universitat Politècnica de Catalunya
C/ Baldiri Reixac 15-21
08028 Barcelona, Spain

EMail: mriss@eel.upc.edu
Tel. +34 93 40 20 213
Fax. +34 93 40 20 183