ABSTRACT
Piezoelectric multi-layer actuators, based on traditional multi-layer capacitor designs, have been designed and tested, and proved robust in service. These devices are manufactured from “soft” piezoelectrics, obtaining larger displacements than hard types, and lend themselves toward d.c. and low frequency applications. Such devices are particularly useful in fast-response applications, where large displacements are less important than operating time (e.g. if the displacement must be achieved in ~ l ms). Such applications include ppm bleed-valves in devices such as mass spectrometers.
Multi-layer actuators have also been fabricated from designs based around the unimorph. Applications for these devices include ink-jet printer heads, proportional valve actuation, and adaptive aerofoil technologies. Actuators have been manufactured with thickness ranging from less than I mm, to greater than 5 mm.
