Temperature gradient method of nonuniformly poling a body of polymeric piezoelectric material and novel flexure elements produced thereby

摘要

A body of polymeric piezoelectric material is nonuniformly poled by establishing a temperature gradient greater than about 10° C. and less than about 100° C. across the thickness of the body and applying an electric field across the thickness of the body in an amount and for a time sufficient to induce nonuniform polarization in the material, whereby a portion of the body near the surface maintained at a lower temperature receives relatively stronger polarization than a portion near the surface maintained at a higher temperature.P PIn a preferred embodiment of the invention, after poling in one direction in a temperature gradient to more strongly polarize a portion of the material near one surface, the temperature gradient and the field polarity are reversed, to polarize a portion of the body near the opposite surface in an opposite direction.PPFlexure mode elements comprising continuous bodies of polymeric piezoelectric material nonuniformly poled according to the method of the present invention exhibit relatively strong flexure mode response to applied fields. A novel flexure mode element produced by one of the methods of the present invention is characterized by having relatively strong polarization near one surface in a direction pointing into the body of material. Another novel flexure mode element produced by one of the preferred methods of the present invention is characterized by having relatively strong polarization in portions near opposite sides of the body and in opposite directions pointing inward toward the body of the material.