First see whether the structure moves by wiggling it with a probe tip.
Hopefully it does!
Try driving it with an sine wave at half of the resonant frequency.
Because the electrostatic force is proportional to the square of the
voltage, the applied force is at twice the applied frequency.
Alternatively, you can add a larger DC voltage to an AC signal at the
resonant frequency, which also gives a force at the resonant frequency.
See the book "An Introduction to Microelectromechanical Systems Engineering,
2nd Edition," pp. 201-202 for the math and more details.
    --Kirt Williams

----- Original Message -----
From: "Behraad Bahreyni" 
To: 
Sent: Tuesday, August 17, 2004 10:34 AM
Subject: [mems-talk] Comb-drive resonators in MUMPS


> Hello all,
>
>   When you send a design for fabrication for fabrication in MUMPS
> technology, a regular comb-drive resonator is often fabricated at the
> edge of your die as a test structure regardless of your design. This
> device is exactly the same as the comb-drive resonator in CaMEL library
> available from Cronos (15 40um fingers, 3um gap/width, 150um beams, and
> 2um thickness).
>
>   I wanted to know if anybody has tested such device and could actually
> drive them into observable (optically or electrically) resonance? The
> simulated resonant frequency of the device is about 24.7kHz, but I have
> been unable to make the device resonate. I am wondering if I am doing
> something fundamentally wrong in my experiments.
>
>   I highly appreciate any help, comments, and experiences.
>
>   Thanks,
>   Behraad
>
>
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