Hi Joe,

In problems like this the sure way to go before u go to test ur membrance is to
simulate your design (the same dimensions as you have fabricated). You can do
analytical calcuations and the rest. Now there are powerful tools like ANSYS and
COMSOL among others that one can use to simulate the behavior of the mirror
before going to the lab to test the membrane.  It is hard to say if everything
is right; no short circuit, counter electrode overlaps the memebrane for the
right deformations, membrane thin enough so the electrostatic force can act on
it etc etc.  why a thin membrane will not deform of an electrostatic force.

Try first to simulate your design and then you can have a feeling what to
expect.

I hope this helps

nimo




________________________________
From: "[email protected]" 
To: [email protected]
Sent: Mon, June 28, 2010 5:07:39 AM
Subject: [mems-talk] About electrostatic actuation of Si membrane

Hi all,
    I'm working on a membrane mirror research, the mirror was fabricated by
anodic bonding of Pyrex 7740 glass to Si wafer.  My idea is, by applying voltage
between the Al electrodes patterned on glasss wafer and the Silicon membrane ,
the membrane will deform through the air gap under the electrostatic force. But,
terriblly, obviously no deformation was observed when even a 300 V voltage is
applied and the air gap is only 20 microns. I have tested the whole structure
and I'm sure that there is no short circuit between the membrane and the Al
electrode, now, I'm desperate and I hope anyone can save me.

Joe