Low frequency mechanical resonator

A method of generating an acoustic resonance signal, said method comprising the steps of:

• providing a substrate;
• providing a piezoelectric device in contact with the substrate, said piezoelectric device including a first piezoelectric layer and a second piezoelectric layer being rigidly secured to each other, said piezoelectric device further including a first electrode positioned on one surface of the first piezoelectric layer opposite to the second piezoelectric layer, said first electrode being a first interdigital transducer including a series of fingers, a second electrode positioned on one surface of the second piezoelectric layer opposite to the first piezoelectric layer, and a third electrode positioned between the first and second piezoelectric layers, said third electrode being a ground reference electrode;
• and
• applying an alternating potential input signal to the first interdigital transducer such that a frequency of the alternating potential signal will cause the first piezoelectric layer to longitudinally contract and expand at a frequency in association with the input signal so as to cause the piezoelectric device to flex at a resonant frequency in order to produce flexural waves in the piezoelectric device, wherein the alternating potential input signal applied to the first interdigital transducer causes the piezoelectric device to flex simultaneously in a plurality of locations.

A flexural mode resonator comprising:

• a substrate including a recess;
• and
• a piezoelectric device positioned on the substrate over the recess, said piezoelectric device including a first piezoelectric layer and a second piezoelectric layer being rigidly secured to each other, said piezoelectric device further including a first interdigital transducer positioned on one surface of the first piezoelectric opposite to the second piezoelectric layer, said first interdigital transducer including a first electrode trace having a plurality of fingers and a second electrode trace having a plurality of fingers such that the fingers of the first electrode trace are intertwined with the fingers of the second electrode trace in an alternating configuration, said piezoelectric device further including a shield electrode positioned between the first piezoelectric layer and the second piezoelectric layer, said shield electrode being a ground reference electrode;
• and
• an alternating potential input signal source means for generating an alternating potential signal said first interdigital transducer being responsive to an alternating potential input signal from the alternating potential signal source means, said alternating potential input signal having a frequency that will cause the first piezoelectric layer to longitudinally compress and expand in association with the alternating potential input signal so as to cause the piezoelectric device to flex at a resonant frequency in order to produce flexural waves in the piezoelectric device.