Unlike all the previous posts I’ve read about bonding PDMS-PDMS I’m
trying
to prevent it.  I’m attempting to bond all but a small section of a PDMS
device to another PDMS device.  I have tried masking and do not believe this
is working (the pressure required

to unpeel the 2 pieces initially is just too high, about 2.5 atm).  As far
as I can see from the chemistry of PDMS, if 1 piece is masked then neither
piece should bond.  I am fairly sure that the mask is in good contact with
the PDMS and I have tried a number of different masking materials.

I don’t know whether there is something that I haven’t understand
about the
surface chemistry of PDMS (have read quite a bit on it, so don’t think so)
or if it is something more annoying like ozone, from the UV/O2 system we use
to oxidise the surface and make the PDMS bond, diffusing through the bulk
and activating the surface behind the mask.  I don’t think so as for one
of
the structures

masked it would have to diffuse 500 um within 3 minutes (the treatment
time).  I do have other options, but masking is certainly the easiest,
fastest and most accurate of the alternatives.

I really don’t feel like masking all but the small section of PDMS I need
unbonded, but any other hints would be much much appreciated.

Cheers all in advance.

Matt Davies
Research Student