# Discussion Forum

## Resistivity change vs deflection

 Topics: 4.3, MEMS, AC/DC Module
RSS feed   |   Turn on email notifications   |   4 Replies   Last post: March 16, 2013 3:46pm UTC

Agnita Sarfarash

March 14, 2013 5:41pm UTC

Resistivity change vs deflection

dear all,

How to plot the resistivity change of a simple piezoresistor vs deflection of a membrane in a MEMS sensor?

thanks

Ivar Kjelberg

March 14, 2013 10:11pm UTC in response to Agnita Sarfarash

Re: Resistivity change vs deflection

Hi

normally you can get impedance info from the defalt lumped port/terminal variables, and for the deflection you must define as a new variable with i.e. an integration of a point, or an average (coupling operator) over a bondary (often cleaner).

Then solve for a parametric seep such to scan your stress levels / displacements, and use a line plot of the resistance with a user defned x axis expression corresponding to your deflection.

You can also do it by plotting a table filled from a few derived variables, by using anual selction of columns

--
Good luck
Ivar

Agnita Sarfarash

March 15, 2013 12:25pm UTC in response to Ivar Kjelberg

Re: Resistivity change vs deflection

Hi Dear Ivar,
First of all I thank you so much for your answer. I simulat the deflection of the membrane but for calculating the resistivity of a resistor is there any example in COMSOl 4.3?

regards

Ivar Kjelberg

March 15, 2013 8:09pm UTC in response to Agnita Sarfarash

Re: Resistivity change vs deflection

Hi

you mean the electric resistance of a conducting media ? I believe so, even the joule heating uses that, implictely, the simples draw your conductor, add one terminal to GND, the second to a given V or I, then solve and plot V/I, it's as simple as that.

Now you can add HT and see it heat up, if your sigma conductance is T dependent you will get R(T), and if you add/replace EC by MEF you can get inductance included for a given frequency

It should be rather straihtforward, no ?

--
Good luck
Ivar

Agnita Sarfarash

March 16, 2013 3:46pm UTC in response to Ivar Kjelberg

Re: Resistivity change vs deflection

Hello Dear Ivar,
Thank you very very much. You solved my problem.

Best regards

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