# COMSOL Blog

## MEMS Tutorial: How to Simulate a Capacitive Pressure Sensor

##### Phil Kinnane | July 24, 2012

Looking for a tutorial on how to model a MEMS problem? We have recently added a video tutorial using the example of how to simulate a capacitive pressure sensor to our video gallery. For a brief overview of what you can model in the MEMS Module watch the trailer below, or go straight to the bottom of this post for a link to download the model files, which show how to produce this type of electromechanics model.

A capacitive pressure sensor uses the fact that pressure changes across a membrane, deflecting it as a result. The change in the air gap results in a change in capacitance of the sensor, which can be directly related to the pressure change that caused this. Modeling this requires coupling the structural mechanics of the device to the electrostatic potential that is used to compute the capacitance.

MEMS devices are, as the name implies, quite small. They are often shipped in a package, or a protective surrounding structure that also provides electrical interconnects. The packaging, which is often made of different (and cheaper) material than the MEMS device, can sometimes affect the operation of the device and care must be taken with the packaging process. This is also investigated in this example as thermal stresses from the package are introduced to the model.

### You Can Simulate a Capacitive Pressure Sensor in the MEMS Module

The capacitive pressure sensor is modeled as a 3D electromechanics problem using the COMSOL Multiphysics MEMS Module. This allows for the definition of the electrostatic, structural and thermal physics in an environment where moving boundaries need to be considered.

For in-depth instructions, watch this full video tutorial on how to model a capacitive pressure sensor. If you have a COMSOL Access account (it’s free and easy to sign up if you don’t already have an account), you may also download the Capacitive Pressure Sensor model, video, and documentation files in the Model Gallery.

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1. Firdaus Ali November 3, 2014   1:17 am

Is it possible to build a simulation on measuring air gap between two different plate (aluminium and stainless steel) using comsol?

Thank you.

2. Phil Kinnane November 3, 2014   11:21 am

Hi Firdaus,

If your question is about how to measure the gap between different deforming domains, then you can set the “Displacement Probes” for two points corresponding to the two domains of the different materials. Yet, if the gap is very small, we recommend to use the “Swept” mesh as done in this particular example for Capacitor Sensor. If you have a specific example where you are trying to do this, and are having difficulty, then you’re always welcome to contact our Support team, support@comsol.com.

Best regards,

Phil