Shear mode transducer and methods

A shear mode transducer apparatus comprising:

• at least a first shear mode piezoelectric element poled along a single direction and having a first outer face and an opposed second outer face;
• a first set of electrodes with a first electrode applied to the first outer face of said first shear mode piezoelectric element, and a second electrode applied to the opposed second outer face of said first shear mode piezoelectric element;
• at least a second shear mode piezoelectric element poled along a single direction and having a first outer face and an opposed second outer face;
• and
• a second set of electrodes with a third electrode applied to the first outer face of said second shear mode piezoelectric element, and a fourth electrode applied to the opposed second outer face of said second shear mode piezoelectric element;
• said at least one first shear mode piezoelectric element is arranged in a stack with said at least one second shear mode piezoelectric element such that said first set of electrodes is in the same plane as said second set of electrodes wherein application of a voltage difference between said first set of electrodes and said second set of electrodes induces longitudinal-flexure electromechanical motion of the stack;
• wherein:
• the first electrode is in the same plane as the third electrode and in electrical contact with the third electrode;
• and
• the second electrode is in the same plane as the fourth electrode and in electrical contact with said fourth electrode;
• wherein application of a voltage difference between the first electrode and the second electrode induces longitudinal-flexure electromechanical motion in the stack;
• and
• wherein said first shear mode piezoelectric element and said second shear mode piezoelectric element are layered in the stack with alternating coordinate rotation angles selected from a zxt+45° and zxt-45° pair and a zxt+225° and zxt-225° pair.