Squeeze-film Effects in Modelling Dynamic MEMS Devices

This work studies the squeeze film effects in dynamic MEMS devices. The emphasis is on the development of compact analytical models due to their amenability in device level simulations using lumped parameters. To provide context to the current work first the computational efficacy of lumped parameter modelling of dynamic MEMS devices is demonstrated in MATLAB/Simulink software environment using a MEMS gyroscope and a MEMS microphone as examples. This is followed by a detailed comparative study of equivalent electrical circuit models for a MEMS microphone wherein the importance of accurate extraction of lumped mass, stiffness and damping due to squeeze film is brought into focus. Consistent expressions are derived for equivalent mass and stiffness of plate and beam structures using Rayleigh¿s energy methods. Discrepancies in modelling compressible squeeze film are brought out and the need for an in depth study of squeeze film behaviour is highlighted leading to a strong motivation for the development of compact squeeze film models.