Squeezed-Film Gas Damping in an Accelerometer
Application ID: 1432
Squeezed-film gas damping is a critical aspect of many MEMS transducers and actuators. In accelerometers, for example, inertia produces a motion that the device detects. A typical structure connects a large proof mass to surrounding structures with elastic beams, which forms a mechanical oscillator with a specific resonance frequency. However, in accurate motion-detection applications these resonances are unwanted, and the device should dampen the movements to produce smooth time-step and frequency responses.
In this model, a narrow gap formed by two solid horizontal plates restricts the displacement of the gas perpendicular to the surfaces. When the sensor squeezes the gap, the gas flows out from its edges. The narrow pathway restricts the flow, which causes gas pressure to increase, which decelerates the plates’ movement.
This example show how the squeezed film gas damping can be coupled to the mechanical displacements in a microsystem accelerometer. Specifically it uses a modeling interface that couples the linearized Reynolds equation, to displacements in the sensor.