I also have no experience of such setups but if you are dropping a
voltage across a 20micron air gap, given the breakdown voltage of air
is 30kV/cm, you'll only be able to apply 60V before breakdown.
Maybe you can try it in a vacuum?

Gareth


On 28/06/2010, Ning Wu  wrote:
> Hi  Joe,
>
> I am not very sure to understand your setup and idea.  But the field
> (300V/20 microns) seems low to me to generate strong electrostatic forces.
> What  you can do is to calculate the force required to deform your membrane
> and see how large the field strength you will need to generate the
> sufficient force.
>
> Ning
>