Poling of a piezoelectric thin film element in a preferred electric field driving direction

A piezoelectric thin film element is provided comprising a first electrode 26; a piezoelectric layer 24 formed on said first electrode; and a second electrode formed 22 on said piezoelectric layer. The piezoelectric layer is poled, by applying a poling electric field across said piezoelectric layer from said first electrode to said second electrode, wherein said second electrode is at a lower potential relative to said first electrode, and wherein said first and second electrodes are configured such that said second electrode is at a lower potential relative to said first electrode when said piezoelectric thin film element is deformed in a deformation direction predominantly opposite to said dipole direction. The first electrode may have a cavity 10 formed below it. The substrate 2 upon which the piezoelectric element is formed may be patterned to reduce the thickness of the substrate. These devices may be made as one of a plurality.