Surface acoustic wave sensors

A surface acoustic wave signal frequency apparatus comprising a crystalline diaphragm section having a cylindrical or spherical outer surface and a cylindrical or spherical inner surface, wherein:

• one of said outer and inner surfaces is adapted for subjection to an applied pressure;
• and
• the other of said outer and inner surfaces includes a first area thereof adapted for the fabrication of a surface acoustic wave device, said first area having a selected crystal lattice arrangement having:
• for a first selected propagation direction, a high sensitivity to pressure effects and a low sensitivity to temperature effects;
• and
• for a second selected propagation direction, a low sensitivity to pressure effects and a high sensitivity to temperature effects.

A surface acoustic wave signal frequency apparatus comprising a crystalline diaphragm section having a cylindrical or spherical outer surface and a cylindrical or spherical inner surface, wherein:

• one of said outer and inner surfaces is adapted for subjection to an applied pressure;
• and
• the other of said outer and inner surfaces includes a first area thereof adapted for the fabrication of a surface acoustic wave device, said first area having a selected contour and a selected displacement from a reference axis normal to the longitudinal axis thereof for providing:
• for a first selected propagation direction, a high sensitivity to pressure effects and a low sensitivity to temperature effects;
• and
• for a second selected propagation direction, a low sensitivity to pressure effects and a high sensitivity to temperature effects.

A surface acoustic wave signal frequency apparatus comprising a crystalline diaphragm section having:

• a cylindrical or spherical outer surface and a cylindrical or spherical inner surface, one of said outer and inner surfaces being adapted for subjection to an applied pressure, and the other of said outer and inner surfaces having at least one area adapted for the fabrication of surface acoustic wave devices;
• first signal frequency means comprising a first portion of said at least one area and a surface acoustic wave device fabricated thereon for propagating surface acoustic waves along a first selected path, the location of said first portion and the direction of said first path being selected to provide primarily force sensitivity;
• and
• second signal frequency means comprising a second portion of said at least one area and a surface acoustic wave device fabricated thereon for propagating surface acoustic waves along a second selected path, the location of said second portion and the direction of said second path being selected to provide primarily temperature sensitivity.

A surface acoustic wave pressure sensor comprising a diaphragm of a continuous crystal lattice structure, having:

• a cylindrical inner surface adapted for subjection to an applied fluid;
• a cylindrical outer surface having an axis parallel to an axis of said inner surface, said outer surface including longitudinally centered thereon an area thereof adapted for the fabrication of surface acoustic wave devices, said area being located such that:
• a first propagation path identified thereon yields a primarily pressure sensitive orientation;
• and
• a second propagation path identified thereon yields a primarily temperature sensitive orientation.

A surface acoustic wave pressure sensor comprising a diaphragm of a continuous crystal lattice structure, having:

• a cylindrical outer surface adapted for subjection to an applied fluid;
• a cylindrical inner surface having an axis parallel to an axis of said outer surface, said inner surface including longitudinally centered thereon an area thereof adapted for the fabrication of surface acoustic wave devices, said area being located such that:
• a first propagation path identified thereon yields a primarily pressure sensitive orientation;
• and
• a second propagation path identified thereon yields a primarily temperature sensitive orientation.

A surface acoustic wave signal frequency apparatus comprising a diaphragm section having a cylindrical or spherical outer surface and a cylindrical or spherical inner surface, wherein:

• one of said outer and inner surfaces is adapted for subjection to an applied isotropic force;
• and
• the other of said outer and inner surfaces includes at least one area adapted for the fabrication of surface acoustic wave devices, the crystal lattice arrangement of said area being selected to provide a primarily force sensitive characteristic and a primarily temperature sensitive characteristic for respective identified propagation directions;
• further comprising means for determining a temperature compensated pressure measurement in accordance with said primarily force sensitive and temperature sensitive characteristics.

A piezoelectric pressure sensor comprising:

• a piezoelectric body having a continuous crystal lattice diaphragm defined by an internal cavity, said diaphragm having an external surface and an internal surface;
• means for exposing said diaphragm to a force representative of the pressure of a medium under investigation;
• a first surface acoustic wave device coupled to one of said external and internal surfaces at a preselected location, said preselected location and the propagation path defined by said first surface acoustic wave device being selected to provide a greater device sensitivity to force than to temperature;
• a second surface acoustic wave device coupled to one of said external and internal surfaces at said preselected location, said preselected location and the propagation path defined by said second surface acoustic wave device being selected to provide a greater device sensitivity to temperature than to force;
• and
• means for maintaining said first and second surface acoustic wave devices in an otherwise benign environment.

A piezoelectric pressure sensor comprising:

• a piezoelectric body having a continuous crystal lattice diaphragm defined by an internal cavity, said diaphragm having an external surface and an internal surface;
• means for exposing said diaphragm to a force representative of the pressure of a medium under investigation;
• a first surface acoustic wave device coupled to one of said external and internal surfaces at a first preselected location, said first preselected location and the propagation path defined by said first surface acoustic wave device being selected to provide a greater device sensitivity to force than to temperature;
• a second surface acoustic wave device coupled to one of said external and internal surfaces at a second preselected location, said second preselected location and the propagation path defined by said second surface acoustic wave device being selected to provide a greater device sensitivity to temperature than to force;
• and
• means for maintaining said first and second surface acoustic wave devices in an otherwise benign environment.