Update on using UV Ozone to bond PDMS and Glass

After posting my observed results from yesterday I came in today to find that one of the segment of the PDMS was strongly bound to the glass cover slip, so strong in fact that trying to remove it caused the cover slip to break. This result comes in response to the comment that Chris made on my previous post. In order to create the PDMS-glass bond the two bonding surfaces need to both be exposed to the UV ozone. To do this they must quickly be put together once the UV Ozone process is complete.

When I set up my experiment yesterday I did not think of this point and I simply laid pieces of PDMS on top of glass cover slips and put them in the chamber. When I took them out to see if they were bound I pulled most of the PDMS off the cover slips and finding them unbound either laied them back down as they had previously been or put them in a separate plastic dish. For  one piece of the PDMS I must have “accidentally” flipped it over onto a segment of cover slip that was exposed to the UV Ozone and thus a bond was formed.

I tried to repeat these results today using the same PDMS segments from yesterday but we were unable to produce any PDMS-glass bonds. I think the reason for this is that the PDMS was contaminated, having been open to the environment over night. Also, today we washed our cover slips in ethanol and DI-water prior to placing them in the chamber, a step we did not do yesterday. Karl has a lot of experience working with PDMS-glass bond formation and he says that he has always removed the PDMS from its cured mold and immediately placed it inside the UV Ozone system to minimize the chance of possible contamination.

Long story short, I made a new batch of PDMS and I am going to try to repeat the experiment later today or tomorrow and hopefully we can repeat the results we got yesterday, but we were able to get PDMS-glass bonding using UV Ozone.

Just a note, I am using the protocol posted on the blog for UV Ozone cleaning.