Results
Add a plot to show how the sensor response varies with temperature. The response is computed at an applied pressure set by the value of the parameter p0, defined as 20 kPa.
1D Plot Group 11
1
In the Home toolbar, click Add Plot Group and choose 1D Plot Group .
2
In the Settings window for 1D Plot Group locate the Data section. From the Dataset list, choose Study 3/Solution 3.
3
On the 1D Plot Group 11 toolbar click Global .
4
In the Settings window for Global click Replace Expression in the upper-right corner of the y-Axis Data section. From the menu, navigate to Component 1 > Electrostatics > Terminals > es.C11 - Maxwell capacitance - F; then double click to select it.
5
Locate the y-Axis Data section. In the table, modify the first row to match the following settings:
Expression
Unit
Description
es.C11
pF
Capacitance
6
In the Model Builder click 1D Plot Group 11 .
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In the Settings window for 1D Plot Group locate the Title section.
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From the Title type list, choose Manual.
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In the Title text area, enter Model Capacitance vs Operating Temperature.
8
Locate the Plot Settings section.
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Select the x-axis label checkbox. In the associated text field, enter Operating Temperature (K).
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In the Label text field enter Capacitance vs Operating Temperature.
10
Click Plot .
At a pressure of 20 kPa the temperature sensitivity of the model is given by the gradient of this curve, approximately 3.5×10-3 pF/K (14×10-3 pF/K for the whole device). Given the pressure sensitivity of 25×10-6 pF/Pa at 20 kPa (for a single quadrant of the device) this corresponds to equivalent pressure of 140 Pa/K in the sensor output. Compared to the noise floor of the measuring circuit proposed in Practical MEMS (0.6 Pa) this number is very large. This model shows that a naive choice of packaging can have a highly detrimental effect on sensor performance.