Hi Nidhi,

I've tried evaporating other materials onto PDMS, and I always observed the
buckling films that you've described.  Others have been able to deposit
smooth films on PDMS with an e-beam evaporator because their set up included
a temperature controller that allowed them to cool the PDMS when they were
doing their deposition.

If you want a thin film of gold on a PDMS slab, you might try one of the
following:

-Deposit the gold without an adhesion layer onto a silicon substrate.  Then
bring the PDMS slab into conformal contact with the film and lift it off the
silicon.  The gold should adhere preferentially to the PDMS.

-Whitesides et al.  have absorbed a photoinitiator into the PDMS and then
exposed the material to UV light to further cross-link the PDMS and increase
its elastic modulus.  The paper is here:
http://pubs.acs.org/doi/full/10.1021/la991302l

-If you don't need PDMS specifically, there are other silicone materials
commercially available that have high elastic moduli and won't buckle after
you deposit a thin film on top.  Look into Dow Corning's WL-5000 series of
silicones.

Hope this helps.


Joshua Tice

Graduate Research Assistant
Kenis Research Group
Dept. of Chemical & Biomolecular Engineering
University of Illinois at Urbana-Champaign
Roger Adams Laboratory, Room 216A, Box C3
600 South Mathews Avenue
Urbana, IL 61801
217-333-2442 (office)
217-244-8068 (fax)


On Wed, Jun 3, 2009 at 2:24 AM, nidhi maheshwari  wrote:

> Hi,
>
> Barbara, thanks for your reply.  I tried reducing the thickness of PDMS
> to around 200-300 microns by spin coating it onto a glass wafer. After
> curing and plasma oxidation I tried sputter of Chrome and Gold. But it
> still showed the same cracked layer. Can you or someone else please
> suggest as to what I should be doing to avoid these cracked metal
> films.
>
> warm regards,
> Nidhi