Characterization and self-test of electrostatically tunable resonators for frequency selective vibration measurements

In this paper, we present a measurement technique for the characterization and the self-test of Single Crystal Reactive Etching and Metallization (SCREAM)-fabricated tunable resonators. Such kinds of structures can be used for frequency selective vibration detection. Spectral information is extracted directly by mechanical filtering at the resonance frequency of the sensor structures. Flexible adjustment of the measurement range is obtained by means of resonance frequency tuning. The structures described in this paper use electrostatic softening (negative springs) to vary the total spring constant of the system. Frequency selective measurements require the exact knowledge of resonance frequency and quality factor. Therefore, a measurement technique for the characterization of the resonance behavior based on electrostatic actuation and capacitive detection of the second harmonic was developed. Undesired coupling effects are eliminated by anti-phase drive signals. Using this method, sensor arrays of tunable resonators are efficiently characterized.