Frequency-Comb-like Behavior in a Resonant MEMS Accelerometer Subject to Blue Sideband Excitation

This work reports an intriguing phenomenon discovered when subjecting a differential resonant MEMS accelerometer to blue sideband excitation (BSE). The exhibited behavior is similar to that of phononic frequency combs (PFCs). The experimental data presents a PFC-like spectrum response, with a collection of equidistant fingers when employing BSE. The spacing of the fingers in the induced frequency comb are unaffected by variations in the BSE parameters (i.e., BSE frequency and BSE amplitude), as well as the equivalent input acceleration. On the other hand, the amplitudes of the frequency comb spectral lines are dependent on the BSE signal parameters, and the equivalent acceleration perturbation. This points to a potential sensing scheme which exploits the amplitude changes of the induced frequency combs - which differs from conventional frequency combs that utilize changes in frequency spacing. The underlying mechanism that governs this phenomenon is the subject of ongoing research. This distinctive behavior, which is induced by employing a relatively unexplored operating scheme, is expected to compete with classical amplitude-modulation-based (AM) resonant sensors.