MEMS stress sensor - QuickField simulation example
MEMS sensor changes its shape under mechanical stress. The electrode plates come close and the variation in electrical capacitance is detected.
How can the MEMS sensor deformation and electrical capacitance in initial and deformed states be calculated?
Answer Typical applications Geometry
Given
Task
Solution
Results
Electric field distribution in the deformed stress sensor
Engineering question
Calculate the initial capacitance electrostatically, solve the sensor deformation under mechanical load, then recalculate capacitance for the deformed geometry.
MEMS stress sensors, capacitive MEMS sensors, microstructure stress detectors
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Simulation problem
Problem Type
Plane-parallel problem of electrostatics and stress analysis .
Young's
modulus
Poisson's
ratio
Silicon
130 GPa
0.1
Copper
140 GPa
0.34
Mechanical deformation and capacitance of a MEMS stress sensor before and after loading, linking structural displacement to the electrical sensing response.
Initially the electrostatic problem is simulated to calculate the native capacitance of the sensor.
Then deformed sensor profile is calculated in stress analysis problem. The profile is exported into the separate geometry model file using Stress Deform tool. That deformed shape model is then used to run another electrostatic analysis to calculate the deformed state capacitance.
Initial capacitance value 0.0026 pF
Capacitance in deformed state 0.0028 pF (+10%)
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