An Investigation on the Effects of Contact in MEMS Oscillators

We investigate the effects of contact in MEMS oscillators by fabricating, testing, and simulating a simple device featuring bilinear stiffness. When the shuttle oscillation exceeds a given threshold, contact with an elastic beam is activated. We first discuss the standard one-cycle response that displays a strongly hardening hysteresis loop. Then, we show that other periodic solutions exist, characterized by multiple cycles and impacts. These are stable only for limited ranges of forcing amplitudes and frequencies and are associated to period doubling bifurcations. The spectrum of the measured and simulated displacements shows an increasingly rich collection of tones similar to what is known as frequency combs in optics.