[mems-talk] PDMS bubble formation...

[Huaibin Zhang]

---- Original message ----
>Date: Fri, 13 Oct 2006 13:32:56 -0700 (PDT)
>From: "g.balsubra manian" <gbalsu_2001 at yahoo.com>  
>Subject: [mems-talk] PDMS bubble formation...  
>To: mems-talk at memsnet.org
>
>Hi Everyone.,
>
>I degassed the PDMS for 1 hr using vacuum dessicator .
>
>I immediately cured the PDMS at same 120 degree
>celcius., no bubbles were found.
>
>When I repeated the same after 30 minutes after
>degassing, lot of bubbles got introduced.
>
>Whether PDMS again absorbs the air (from atmosphere)
>after degassing????

Hi,
I don't quite understand the situation you described. You mean the bubble in the channel when you introduce fluid or bubble inside the PDMS when you cure it. 
If you mean the bubble in the channel, it is important to know how you introduce fluid into your channel? Channel outgas technique is a good way to fill channel without generating bubble. 
One thing for sure is that PDMS is gas permeable. To me, there is some gas adsorped inside PDMS. In some cases, if you use vacuum to suck fluid into channel, bubbles may emerge from PDMS wall.

Huaibin Zhang