Rainbow actuators and sensors: A new smart technology

Recent developments in the technology of ferroelectric, piezoelectric, electrostrictive and antiferroelectric ceramic actuators have clearly demonstrated that the materials required for future applications such as positioners, levelers, pumps, vibration-free structures and variable-focus elements will need to be more sophisticated (multifunctional and smart), more economical and possess a higher degree of performance than presently available. One recently developed method for producing considerably higher-than-normal displacement in these materials is known as the RAINBOW (Reduced and INternally Biased Oxide Wafer) technology. This acronym denotes the basic active structure of the Rainbow device which is produced by a special high temperature chemical reduction process. In its most basic sense, a Rainbow can be considered to be a pre-stressed, monolithic, axial-mode bender; however, because of its unique dome or saddle-shaped configuration, it is able to produce much higher displacements (up to several mm depending on size) and sustain moderate loads (up to 10 kg depending on thickness) than normal benders such as unimorphs and bimorphs. The technology of producing and characterizing such Rainbows as well as methods for increasing their utility by means of stacked actuators for increased linear displacement and matrix arrays for enhanced coverage in wide-area applications such as smart skins, autoleveling structures and deformable coatings are described.