Collective dynamics and pattern switching in an array of parametrically excited micro cantilevers interacting through fringing electrostatic fields

We report on an experimental observation of synchronization and abrupt transitions between standing wave patterns in arrays of micromechanical oscillators. The architecture of flexible cantilever arrays parametrically excited by and interacting through time-dependent fringing electrostatic fields allows tuning of an interaction potential and supports traveling waves. The arrays consisting of 500 μm long and 5 μm thick single crystal Si cantilevers were fabricated from silicon on insulator substrates. The out-of-plane resonant responses were visualized by time-averaged temporally aliased video imaging and measured by laser Doppler vibrometry. Our experimental and reduced order model results collectively demonstrate that under a slowly varying drive frequency the standing wave patterns remain unchanged in certain frequencies intervals, followed by an abrupt change in the pattern.