Application of parametric resonance amplification in a single-crystal silicon micro-oscillator based mass sensor

A mass sensing concept based on parametric resonance amplification is proposed and experimentally investigated using a non-interdigitated comb-finger driven micro-oscillator. Mass change can be detected by measuring frequency shift at the boundary of the first order parametric resonance 'tongue'. Both platinum deposition using focused ion beam (FIB) and water vapor desorption and absorption are used to change the mass of a prototype sensor. Due to the sharp transition in amplitude caused by parametric resonance, the sensitivity is 1-2 order of magnitude higher than the same oscillator working at Simple Harmonic Resonance (SHR) mode in air. Picogram (10(-12) g) level mass change can be easily detected in the sensor with mass about 30 ng and resonance frequency less than 100 kHz. Damping effects and noise processes on sensor dynamics and sensing performance are also investigated and damping has no significant effect on sensor noise floor and sensitivity. Higher sensitivity is expected when the oscillator design is optimized and dimensions are scaled. (C) 2005 Elsevier B.V. All rights reserved.