Dear Willie,

PDMS bonded to silicon can generally withstand only a few bar
overpressure before delamination. Depending on the flow the flow you
want to use in your channels, the pressure drop generated may very well
exceed the delamination pressure. I would advise estimating the pressure
drop.

Pressure drop correlations for rectangular geometries can be found
(amongst others) in:
Shah - Laminar Flow Forced Convection in Ducts (1978), Chapter 5

Because I do not know the exact geometry you are using, a paper on the
deformation of PDMS channels by pressure drop due to flow might also
interest you:
Gervais - Lab Chip 6 500 (2006)

Good luck. If you are having trouble, feel free to contact me.

Kind regards,

Dirk Renckens
Chem Eng PhD Candidate
Delft University of Technology

-----Original Message-----
From: willfeng@bu.edu [mailto:willfeng@bu.edu]
Sent: 02 April 2009 18:42
To: mems-talk@memsnet.org
Subject: [mems-talk] PDMS flow cell bonding to silicon

I am looking for advice to bond a PDMS flow cell to a silicon chip.
When I attempt to send fluid through the 20um wide and 120um high
channels, the PDMS lifts off the silicon wafer. I usually clean the
PDMS and the silicon using 20sscm flow of oxygen with an RIE, at 100W
50mTorr for 1 minute. The PDMS flow cell is approxiately 10mm x 5mm.
Has anyone had success with a PDMS sample of that size? Thank you for
your time.

Willie Feng