Enhanced Frequency Resolution in Parametrically Resonant Microcantilever Sensors

This work details the resonant frequency measurement of a silicon microcantilever using the features of the parametric resonance spectrum in the interest of designing a mass sensing resonator. Measured frequency resolution is demonstrated to be approximately 0.003 Hz for a device of frequency 30 kHz at room temperature, or 100 parts per billion. The cantilever motion is actuated and sensed electromechanically by Lorentz forces and induced electromotive force (EMF), respectively, using a static magnetic field generated by a proximal permanent magnet. Although direct comparison between frequency resolution in harmonic systems and in parametric systems is complex and has yet to be analytically determined, this platform circumvents limitations in oscillation amplitude imposed on harmonic systems and exhibits extremely high frequency resolution and may thereby be more desirable for micro-and nano-scale mass sensor applications.