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capacitive pressure sensor

Posted 29.06.2012, 11:31 GMT-4 MEMS & Nanotechnology, MEMS & Piezoelectric Devices Version 4.2a 2 Replies

Chenyang Wu
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I'm trying to simulate a parallel-plate capacitive pressure sensor. The plates are fixed along the edges, but the top plate can deflect under pressure; thus the capacitance changes.

I am using electrostatics and solid mechanics physics.The problem is, in order to compute the capacitance, I have to add air surrounding and also in between the plates. But air doesn't work in solid mechanics physics, as Young's modulus and poisson's ratio are required. And in fact, it is only vacuum between the parallel plates.

What should I do?
Thank you!
2 Replies Last Post 29.06.2012, 16:02 GMT-4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 29.06.2012, 15:12 GMT-4
Hi

Indeed air is not a structural material, although it is possible to cheat a bit and make air a soft material, hence to get the mesh to deform due to the true structural material deformation, but it's by far cleaner to use the ALE (first) then to have the structural deformation deform the air mesh, and analyse the ES on the ALE deformed mesh.

This is already what is put into the EMI physics, everything "pre-cooked" so that is the shortest way. There are a few examples by the model library, take a look and do a few similar examples first

--
Good luck
Ivar
Hi Indeed air is not a structural material, although it is possible to cheat a bit and make air a soft material, hence to get the mesh to deform due to the true structural material deformation, but it's by far cleaner to use the ALE (first) then to have the structural deformation deform the air mesh, and analyse the ES on the ALE deformed mesh. This is already what is put into the EMI physics, everything "pre-cooked" so that is the shortest way. There are a few examples by the model library, take a look and do a few similar examples first -- Good luck Ivar
Chenyang Wu
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Posted: 1 decade ago 29.06.2012, 16:02 GMT-4
Thank you!
Thank you!

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