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saw sensor for pressure measurement
Posted Mar 1, 2012, 6:43 a.m. EST MEMS & Nanotechnology, MEMS & Piezoelectric Devices, Computational Fluid Dynamics (CFD), Parameters, Variables, & Functions Version 4.2a, Version 4.3, Version 4.3a 33 Replies
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i am designing a saw sensor for pressure measurement.can somebody suggest me which formula i need to use in comsol in order to measure pressure. it should be related to change in frequency of saw sensor by application of pressure.
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I don't think anybody can suggest a formula. The procedure will be:
1. Set up your model with proper electrical and mechanical boundary conditions
2. Apply pressure to the appropriate boundary
3. Determine the electrical frequency response of the system.
Put all this into a parametric study using pressure as the parameter.
This will give you the pressure-frequency relationship and you might try to fit this to an appropriate test function to obtain a formula. What the test function could look like depends on your SAW design.
Cheers
Edgar
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Thank you for your reply. I have designed the idt structure and given the boundary conditions also both mechanical and electrical.I am new to this comsol software so dont know much about it. Should i send you my model .If u review it and help me finding suitable solution i will be grateful to you sir.
Looking forward to your reply.
Regards
Rohan kumar
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Can you attach your file?
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How is your work ? i am also designing a saw sensor for pressure measurement. I have post some picture which I got.
I think we can exchange more.
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Thank you for your reply.yes we can exchange information about the design. So which version of COMSOL you are using ?What is the range of your pressure measurement ?
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Thanks for your enthusiasm. I use version 4.2, which i put pressure on the surface is 10kpa. i think i have simulated fairly accurately, but I do not understand why the input and output frequency does not change. Do you have trouble like me ?
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Thank you for your reply. Can you send me your simulation i will check it. There must be change in frequency. Let me check it if you don't have any problem.Waiting for your reply.
Regards
Rohan Kumar
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I'm glad because of your suggestion. Yes, this is my file. I have difficulty in placing pressure on the boundary condition to see the change of frequency that I put in.
Expecting your answer.
Nguyên Vinh
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I am also designing a SAW pressure Sensor.
I read that you are designing a SAW sensor, so it would be great that we could work together. Right now I am simulating a single cell of the IDT. I am working with 128 YX LiNBO3. I got the expect results, and now I am trying to simulate a ten electrodes IDT, but I have some issues with the PML boundaries.
Waiting for your answer
Regards,
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I also think it's a great idea for all of us. Yes, I am willing to exchange about this design. Can you post your file?. I do not know the domain that you analyze , because I think each region will have different boundary conditions. if you analyze the Eigenfrequency domain, I think I have a simulation that you can refer.
Andrés Guillermo Borrero, can you solve my problems ? I have difficulty in placing pressure on the boundary condition to see the change of frequency that I put in.
I'm very grateful if someone could help me ?
Expecting to soon get an answer.
Regards
Nguyên Vinh
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YOU SHOULD DESIGN THE SNGLE IDT STRUCTURE FIRST LIKE Andrés Guillermo Borrero. which papers you are following can you send them
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YOU SHOULD DESIGN THE SNGLE IDT STRUCTURE FIRST LIKE Andrés Guillermo Borrero. which papers you are following can you send them
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I also design original the single IDT structure first, I find the appropriate frequencies. I then analyzed in the time domain, I want to see the movement of the saw depends on time. I've put a sine wave on the electrodes of IDT. and I've seen results. however, now I want to put pressure on the surface of the sensor, and check the frequency that I applied to the sine wave equation has changed or not., my work did not as expected.
Rohan Kumar,How did you simulate on this change . is it like me ?
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yes i simulated the single idt .it is working . i did the frequency analysis of the structure . i found the resonant frequency of the idt 1st then applied the pressure to it . there was a frequency shift because of that.
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I simulated also like you. I have seen the frequency change. you do not work in the time domain analysis. in fact, we must apply the sine wave signal and determines the pressure through the change of output frequency.
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yes you are right. can you send the single idt structure.we have to do like this.
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Because of the large file size, I can not post up. I take a page so we can see that
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delete the study part from simulation and send it . or zip it and send it to my email id rohankumar03@gmail.com as i dont have office file in my i system
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I just created file as I did before. it is based on modules of COMSOL library. you can change the pressure (large enough) to see the frequency change
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Here are my files. IDT Celda Unitaria is a single IDT, I have performed a frequency analysis to see the admitance. I Also attached this graphic (Admitancia IDT celda con 60 Lambda) . Prueba SAW IDT is a 10 electrodes IDT, with this I have a problem with PML boundaries that I used to avoid the reflections on the material frontiers (The error i get from comsol is "Comsol could not find any spherical or cylindrical regions."). Al so I Attached the results about admitance (Admitancia IDT 10 Electrodos ...).
Please, let me know if you can resolve the problems with PML. I am using COMSOL 4.2a
I have not performed any simulations with pressure yet. How do you simulate the diaphragm bending??
Waiting for your reply.
Regards.
Guillermo Borrero
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it is a pity, I can not open your file. I used version 4.2.Can you capture images of what you did and send it to me ?
Regards.
Nguyên Vinh
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Sure I can send you the images. I try to put all necessary to understand what I do for each case. Let me know any doubt. In the ten electrodes IDT the PML regions do not work properly, they seems to be disconected of the entire system.
Let me know if you have any suggestion or comment.
Waiting your reply.
Regards
Guillermo Borrero
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I think that they seems to be disconected of the entire system is correct. My opinion, PML is a piezoelectric material, and what you simulate is for PML. the remaining components are not related to PML. I do not know how you put the fixed conditions for the model. Let me know this.
Guillermo Borrero,Can you tell me how you simulate the pressure conditions in your model ?
Regards
Nguyên Vinh
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I do not understand when you say that PML is a piezoelectric material. PML is a kind of boundary to avoid the reflections on the material frontiers.
What fixed conditions specifically do you refer ?
Currently I am not simulating pressure conditions, before I want to create the correct model of the IDT and next I will add the reflectors and I think I should put all in a kind of diaphragm, so with the pressure to generate a bending of it. And a change in propagation velocity and delay time.
Let me know what is your plan?
waiting for your answer and comments.
Regards.
PS : do you have facebook or anything so we can chat?
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I'm sorry I was a bit busy now.
My plan is I will put a sine wave on the electrodes, and I applied pressure to the surface. I want to see the change in frequency of the system. But that can not,I do not know what i have do now
www.comsol.com/community/forums/general/thread/14491/ . I think the information here will be useful for your simulation.
Regards
Nguyên Vinh
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Thanks, I already had seen that forum, but I was not able to fix my errors. Are you designing a delay line sensor or a saw resonator sensor?. Do you use PML?. Did you get the admitance of the device?. How do you plan see the frequency shift: either performing a time domain simulation or frequency domain simulation?
Can you send me your file?
Waiting for your reply.
Regards
Guillermo
PS: do you have facebook or something else so we can chat? and share the information easier.
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i am doing what you are planning to do . i have a elastic diaphragm on which the subsrate beam is placed on which the saw sensor is mounted. i am giving a pessure from he bottom of the diaphragm . i will send you the design of the structure tommorow.
Regards
Rohan
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Ok, thank you.
I really appreciate your help with this.
Regards
Guillermo
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did you worked out your PML problem? If yes, I am very interested: I am trying to model a SAW propagating on 128° YX LiNbO3 (by the way, thank you for the elastic, coupling and permittivity matrix, i could not make the rotated coordinate system work properly...); and I don't know how PML work... Did you finally understand and solve your problem?
Thanks a lot!
Sylvain
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In order to solve the problem with the PML's, I used rectangular structures on each side of the substrate, and then I defined them as PML, geometry type Cartesian. This way the PML's worked properly in my model.
Regards.
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Thank you for your answer, do you know what is the importance of PML scaling factor and PML order?
Regards,
Sylvain
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I am designing a SAW tire pressure sensor .I added mass to the surface of the substrate,the eigenfrequency changed , I am not sure this is correct. Could you please help me check it ,thanks..
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