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Ph. Moll, G. Pfusterschmied, M. Schneider, M. Dorfmeister, U. Schmid:
"Piezoelectric Switching Of Bistable Mems Membranes In Fluids";
Talk: IEEE 34th International Conference on Micro Electro Mechanical Systems (MEMS), online; 01-25-2021 - 01-29-2021; in: "2021 IEEE 34th International Conference on Micro Electro Mechanical Systems (MEMS)", IEEE, (2021), ISBN: 978-1-6654-1912-3; 544 - 547.

In this paper, we demonstrate bistable switching
of micromachined membranes with integrated
piezoelectric thin film actuators in liquids with a dynamic
viscosity up to 286 mPa·s. The membranes have diameters
between 600 to 800 µm and a total layer stack thickness of
3.3 µm, thus enabling membrane displacements up to
20 µm, when switching from one ground state to the other.
To predict the switching behavior in fluids, pre-evaluation
was carried out in air. The resonance frequency of the first
vibrational mode fres1 provided information, if such a
membrane is switchable. In contrast, in liquids only the
membrane center velocity at fres1 showed a tendency to
predict the switching behavior of the membranes.
However, neither the viscosity nor the density affected the
displacement heights between the two ground states during
switching procedures. By stimulating the switching process
purely electrically, a great variety of new applications of
such membranes is unlocked like as fluid valves, PMUTs
in fluids or bio-sensors.

http://dx.doi.org/10.1109/MEMS51782.2021.9375163