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