Vishwanath,

1) The purpose of O2 plasma treatment is creating a "wet" surface. You can place
a drop of water on that surface. You should see the water rapidly spread out. If
you have equipment for contact angles measurements, you can monitor this process
better and easiler.

2) If you use Sylgard 184 (Dow Corning), this curing condition is 4 hr at 65C.
Please check your product sheet for detail.

3) If you peel off the PDMS layer from the substrate (especially thin film
<50um) after curing or O2 treatment, it would NOT easy to bond. I have not
figured out why.

4) I did NOT have any problems to bond 2 PDMS layers after O2 plasma treatment.
I just push them together immediately after the O2 treatment.

Good luck,

Lydia