disable Donut outputcache for mobile devices

Hi,

i am using Donut outputcache and it's doing problems with my mobile site,
it appears that when a mobile device goes to my site, it gets the cached version of a the desktop site.
only when i disable the Donut outputcache, the mobile gets the right version.

how can i disable the output cache just for the mobile site ?

Thanks,
Shay

any idea ?
it will improve performance a lot if it works.

Thanks,
Shay