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piezoelectric MEMS multyphysics modeling
Posted Jun 24, 2010, 8:51 a.m. EDT 3 Replies
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Good evening.
I want to simulate a piezoelectric MEMS device. I want to take confidence with COMSOL Multiphysics and thus I am trying to model a simple silicon cantilever with on top a PZT layer sandwiched by two conductive layers acting as electrodes.
I tryed using the "Piezo Solid" module in the "MEMS module -> structural mechanics" category (smpz3d) alone but when I clamp on one side my structure and I deform it on the other side I got a voltage gradient inside the conductive layer which is obviously nonsense.
I then thought that electrical conduction is not taken into account in that module so I tried a "multiphysics" simulation, adding the "Conductive Media DC" module in the "MEMS module -> Electrostatics" category. Now no voltage gradient inside the electrodes but still nonsensical results: even if I let the two electrodes floating I get zero voltage on both. I tried also to keep one grounded and the other floating but I got the same result.
Anyone has an idea of which can be the problem or where I can find more details about multiphysics simulations? In the manuals I found only built-in cases...
Thanks a lot and have a nice day.
I want to simulate a piezoelectric MEMS device. I want to take confidence with COMSOL Multiphysics and thus I am trying to model a simple silicon cantilever with on top a PZT layer sandwiched by two conductive layers acting as electrodes.
I tryed using the "Piezo Solid" module in the "MEMS module -> structural mechanics" category (smpz3d) alone but when I clamp on one side my structure and I deform it on the other side I got a voltage gradient inside the conductive layer which is obviously nonsense.
I then thought that electrical conduction is not taken into account in that module so I tried a "multiphysics" simulation, adding the "Conductive Media DC" module in the "MEMS module -> Electrostatics" category. Now no voltage gradient inside the electrodes but still nonsensical results: even if I let the two electrodes floating I get zero voltage on both. I tried also to keep one grounded and the other floating but I got the same result.
Anyone has an idea of which can be the problem or where I can find more details about multiphysics simulations? In the manuals I found only built-in cases...
Thanks a lot and have a nice day.
3 Replies Last Post Jun 30, 2010, 3:48 a.m. EDT
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Posted:
1 decade ago
Hi
not sure I fully understand what you really get, but one thing to be aware of, in PZT mode, is that the dielectric and PZT tensor order are different (default to IEE E convention) than for classical structural stress tensor, check the documentation (in V4 it is reminded, but one must read carefully the xy yx yz zy ... orders.
This makes easily erors in what truely is the coordinate transform one are using for the material definition, and as the custom coordinate one defined are not easily visulaised, these are also easy to get all wrong.
These two are the most common error I have had, for the rest COMSOl is working nicely for PZT simulations (actually 3.5a, my exprience with v4 and PZT is still limited)
Have fun Comsoling
Ivar
not sure I fully understand what you really get, but one thing to be aware of, in PZT mode, is that the dielectric and PZT tensor order are different (default to IEE E convention) than for classical structural stress tensor, check the documentation (in V4 it is reminded, but one must read carefully the xy yx yz zy ... orders.
This makes easily erors in what truely is the coordinate transform one are using for the material definition, and as the custom coordinate one defined are not easily visulaised, these are also easy to get all wrong.
These two are the most common error I have had, for the rest COMSOl is working nicely for PZT simulations (actually 3.5a, my exprience with v4 and PZT is still limited)
Have fun Comsoling
Ivar
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Posted:
1 decade ago
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Thanks a lot everybody
My goal is to model a PZT thin film with an interdigitated structure upon it. Thus I coupled the "MEMS module -> Piezo Solid" application mode together with the "MEMS module -> Conductive Media DC"; with the first in the "unsymmetric, electrostatic" electrical formulation mode (to make it compatible with the conductive media DC application mode, as stated in the manual).
Piezo solid application mode is active only for the piezoelectric material and Conductive media DC only for the electrodes. In order to model the electric contact I placed at this interface the "electric potential" boundary setting, and I used the dependent variable "V" as value.
Now there's no voltage gradient inside, but there's never voltage difference between the electrodes, indipendently of
a) deformation of the structure
b) both electrodes floating or one grounded.
Anybody has an idea about which could be my mistake? It seems weird to me since every piezoelectric MEMS needs at least one electrode. Which is the correct way to model this?
PS: attached you can find my model
Thanks a lot everybody...
My goal is to model a PZT thin film with an interdigitated structure upon it. Thus I coupled the "MEMS module -> Piezo Solid" application mode together with the "MEMS module -> Conductive Media DC"; with the first in the "unsymmetric, electrostatic" electrical formulation mode (to make it compatible with the conductive media DC application mode, as stated in the manual).
Piezo solid application mode is active only for the piezoelectric material and Conductive media DC only for the electrodes. In order to model the electric contact I placed at this interface the "electric potential" boundary setting, and I used the dependent variable "V" as value.
Now there's no voltage gradient inside, but there's never voltage difference between the electrodes, indipendently of
a) deformation of the structure
b) both electrodes floating or one grounded.
Anybody has an idea about which could be my mistake? It seems weird to me since every piezoelectric MEMS needs at least one electrode. Which is the correct way to model this?
PS: attached you can find my model
Thanks a lot everybody...
Attachments: