How to extract the capacitance between deflected parallel plates ?

Dear all,

I have a problem extracting the capacitance between two parallel plates when one of them is deflected due to electrostatic force.
(1) The two parallel plates are made of Silicon and are biased at 0V & 1V.
(2) There is an Air layer in between the two plates.
(3) I used three physics to analyze the case : Solid Mechanics, Electrostatics and Moving Mesh.

So far, it seems I can only extract the capacitance when there is no electrostatic force induced deflection. The capacitance doesn't change with different electrostatic force (deflection). I think the main problem in my simulation is lack of a "Link" between Solid Mechanics and Electrostatic Physics which can bring the mechanical effect into the electrostatic analysis.

Can anyone help me with this problem ?
Please find my .mph file in the attached document.

Thank you so much !!!!

Pantani