Air damping as design feature in lateral oscillators

The damping of an oscillator is, next to the effective mass and the stiffness, one of the key parameters that determine its frequency response as well as its noise. Since there are numerous different applications for oscillating microstructures, there are also numerous requirements for the shape of the respective resonance peak. While fabricating the right mass and stiffness to obtain a desired resonance frequency is, in general, a basic task, designing a micro-oscillator featuring an intended damping is not trivial. We present a way of utilizing the surrounding air to adjust the passive damping of a laterally oscillating micromechanical system. This is shown to hold in a relatively wide range by comparing analytical models and finite volume method simulations with measurements of a number of micro-electro-mechanical test structures with optical readout.