Using the Nonlinear Duffing Effect of Piezoelectric Micro-Oscillators for Wide-Range Pressure Sensing

This paper investigates the resonant behaviour of silicon-based micro-oscillators with a length 3600 µm, width 1800 µm and thickness 10 over wide range ambient gas (N2) pressures, extending six orders magnitude from 10−3 mbar to 900 mbar. The oscillators are actuated piezoelectrically by thin-film aluminium-nitride (AlN) layer, cantilever coverage area being varied 33% up 100%. central focus is on nonlinear Duffing effects, occurring at higher oscillation amplitudes. A theoretical background provided. All relevant parameters describing oscillator, such as stiffness for each size well different bending modes more complex modes, extracted experimental data. so-called 2nd roof-tile-shaped mode showed highest value −97.3∙107 m−2s−2. Thus, it was chosen optimal extended pressure measurements. Interestingly, both spring softening effect hardening were observed in this mode, depending percentage AlN area. Duffing-effect-induced frequency shift found be obtaining sensitivity, while hysteresis loop also very useful parameter because possibility eliminating temperature influences long-term drift effects resonance frequency. An reasonable application-specific compromise between sensitivity measurement can selected adjusting excitation voltage, offering much flexibility. novel approach turns out promising compact, cost-effective, wide-range measurements vacuum range.