Electroosmosis problems

I am having some problems with my electroosmosis device and I was hoping that people with more knowledge about the TEM chips might have some suggestions.  For these trials, I used membranes from a wafer labeled 412-S.  I am still using the PDMS device from my last post although now I have mini “clamps” that I made from pieces of a paperclip.  These help hold the PDMS pieces together.  I seemed to have solved the problem of filling the device but have replaced it with the problem of bursting the membrane.

To fill the device I place a TEM chip on one of the PDMS pieces and place one drop of 0.1M KCl solution on the surface.  I don’t let the drop fall, I let the water bead up on a syringe and touch the drop to the chip.  I put the two pieces together so that the openings line up.  Then I use the syringe pump to fill the device with the KCl solution at a rate of 1uL/min.  Air bubbles are still forming on the side of the chip opposite of the pump.  I have been able to remove these from some combination of gravity and transpiration (touching the end of the capillary tube to a paper towel to help pull the bubble).

At some point during these steps, I am breaking the membrane.  I know at least that the membrane is not breaking from the two pieces coming into contact because I have put the pieces together then taken them apart and observed that the membrane is still intact.  My guesses are that I’m pumping at too high of a rate, possibly putting too much pressure on the pieces when I hold them together or, although probably unlikely, using too high of a salt concentration.

I would love to hear thoughts and comments.  I know there are people out there that know more about these chips than me.