Discussion Forum

I want to calculate Y11 admittance and I want to draw admittance versus frequency plot for observing resonant frequency shift before and after exposure of the gas.apals let me know

what is the process of exposing SAW gas sensor to a gas in COMSOL?

Hi,

Check the application library model under Acoustics Module > Ultrasound > saw_gas_sensor.

Cheers Edgar

Sir, Thank you for th e reply .but i have already designed a model but iam unable to plot the admittance versus frequency plots which gives information about frequency shift.(resonance frequency before exposure to the gas and after exposure to the gas.)In the model which you suggested me to refer didnot find the admittance but they are able to tell that the resoance frequency shift .my doubt is how to plot the admiitance versus frequency plot.since so many days iam struggling for it but i couldnot get the result.pls help me.

Admittance is Current/Voltage. So you need to determine the voltage on the electrodes and the current flowing. This is probably easiest if the electrodes are setup as terminals.

Cheers Edgar

Sir, Thank you for the reply. In my model Iam using Interdigitated Electrode configuration.Iam treating electrodes as terminals as you have mentioned. As Iam new to COMSOL please let me know how to know voltage on the electordes and current flowing through the electrodes.

Iam herewith sending the comsol file pls let me know the modifications that are to be done for getting a proper admittance versus frequency curve.,resonance and antiresonance values from eigen frequency study.

my another doubt is how to apply sinusoidal voltgae to the IDE(Inter digitated Electrodes).

1. If you do frequency dependent analysis all signals are sinusoids.
2. Define one electrode as Terminal, another as Ground.
3. Create a Global Evaluation node, insert es.I0_1/es.V0_1, evaluate, and plot. (if the terminal is Terminal 2 then es.I0_2, etc.

D.W. Greve DWGreve Consulting

By the way, the .lock file isn't openable.

Sir, Thank you for the reply.I have followed the instructions as per the COMSOL for uploaidng the files.But even then I have tried to upload.After uploading Iam getting "Your upload timed out" meesage. Suggest me some way to upload my file.

Iam herewith attaching the image of my device for reference as there is a problem with the file upload. pls suggest some way to upload the file I will upload the file and I can have some suggestions from you.

Is frequency domain analysis is same as frequency dependent analysis?

As the configuration of IDT is in Interdigitated in fashion ho wto provide voltage as per your suggestion.Pls let me know.Iam eagerly waiting for your reply.

Is frequency domain analysis is same as frequency dependent analysis?

Yes.

I can't tell what the problem is with file upload. The image is no help in figuring out what your problem is.

In general I advise setting up and solving a simpler, smaller 2D problem before attempting a 3D solution.

DWG

Sir thank you for the reply.can i send the file to you by email.since so many days iam struggling to know what is the problem in the model and due to that unable to plot admittance versus frequency