A piezoelectric device comprising: a piezoresonator body having opposing first and second surfaces and opposing third and fourth surfaces, said first and said second surfaces being substantially parallel to first and second longitudinal axes of said piezoresonator body, said third and said fourth surfaces being substantially parallel to said first longitudinal axis and substantially perpendicular to said second longitudinal axis, and said first and said second longitudinal axes being substantially perpendicular to each other; at least one common electrode disposed on said second surface; a plurality of electrodes disposed on said first surface (4a, 4b), said plurality of electrodes comprising one or more pairs of excitation electrodes, each of said pairs of excitation electrodes comprising a first electrode and a second electrode positioned along a first direction along said first longitudinal axis; one or more contact elements disposed on at least one of said third and said fourth surfaces at one or more contact locations, each of said contact locations at least partially aligned between said first and said second electrodes of one of said pairs of excitation electrodes; and an alternating voltage source, said alternating voltage source configured for applying an alternating voltage to said common electrode and one of said first and said electrodes in each of said pairs of excitation electrodes to cause a nano-elliptical motion of at least a portion of said contact elements, said nano-elliptical motion substantially parallel to said first and said second surfaces, wherein said nano-elliptical motion of said portion of said contact elements disposed on said third surface is in a first elliptical path, wherein said nano-elliptical motion of said portion of said contact elements disposed on said fourth surface is in a second elliptical path opposite to said first elliptical path; wherein said piezoelectric body has a first order natural resonance frequency ( v 1) for a first standing longitudinal wave in a direction of said second longitudinal axis, an even order natural resonance frequency ( v 2) for a second standing longitudinal wave in a direction of said first longitudinal axis, wherein: 0 % < v 1 - v 2 v 1 + v 2 / 2 * 100 % ≤ 20 %; and wherein a frequency ( v 3) of said alternating voltage source is between v 1 and v 2. a piezoresonator body having opposing first and second surfaces and opposing third and fourth surfaces, said first and said second surfaces being substantially parallel to first and second longitudinal axes of said piezoresonator body, said third and said fourth surfaces being substantially parallel to said first longitudinal axis and substantially perpendicular to said second longitudinal axis, and said first and said second longitudinal axes being substantially perpendicular to each other; at least one common electrode disposed on said second surface; a plurality of electrodes disposed on said first surface (4a, 4b), said plurality of electrodes comprising one or more pairs of excitation electrodes, each of said pairs of excitation electrodes comprising a first electrode and a second electrode positioned along a first direction along said first longitudinal axis; one or more contact elements disposed on at least one of said third and said fourth surfaces at one or more contact locations, each of said contact locations at least partially aligned between said first and said second electrodes of one of said pairs of excitation electrodes; and an alternating voltage source, said alternating voltage source configured for applying an alternating voltage to said common electrode and one of said first and said electrodes in each of said pairs of excitation electrodes to cause a nano-elliptical motion of at least a portion of said contact elements, said nano-elliptical motion substantially parallel to said first and said second surfaces, wherein said nano-elliptical motion of said portion of said contact elements disposed on said third surface is in a first elliptical path, wherein said nano-elliptical motion of said portion of said contact elements disposed on said fourth surface is in a second elliptical path opposite to said first elliptical path; wherein said piezoelectric body has a first order natural resonance frequency ( v 1) for a first standing longitudinal wave in a direction of said second longitudinal axis, an even order natural resonance frequency ( v 2) for a second standing longitudinal wave in a direction of said first longitudinal axis, wherein: 0 % < v 1 - v 2 v 1 + v 2 / 2 * 100 % ≤ 20 %; and wherein a frequency ( v 3) of said alternating voltage source is between v 1 and v 2.