Sensor, system, and method, for measuring fluid properties using Multi-Mode Quasi-Shear-Horizontal Resonator
First Claim
1. A method of measuring at least two fluid properties selected from density, viscosity, and elastic modulus, when the third of said fluid properties is known or assumed, the method comprising the steps of:
- providing a Multi Mode Quasi Shear Horizontal Resonator (MMQSHR) having an energy input, and a measuring surface for contacting said fluid, said measuring surface having at least a first region and a second region, and a separation area defined therebetween;
feeding said MMQSHR with excitation energy via said input, at a first and a second frequencies selected to excite a first and a second acoustic modes respectively, each of said acoustic modes causing a component of horizontal shear wave motion in said surface,wherein excitation in said first frequency further causing said regions to move in phase relative to each other;
and wherein excitation in said second frequency causes said two regions to move out-of-phase relative to each other, inducing a vertical displacement in said separation area;
measuring energy related parameters at said first mode and second mode;
calculating two of said fluid properties utilizing said energy related parameters and information relating to said third fluid property.
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Abstract
A system and a method for providing information on two of the three variables, density (ρ), viscosity (η), and elastic modulus (c) of a fluid, such that independent knowledge of one variable allows the remaining two variables to be measured by a single sensor. The present invention relies on the interaction of a predominantly shear horizontal acoustic wave device (“quasi-shear-horizontal”) with the fluid, so as to measure subtle differences in the interaction of two or more acoustic resonance states or waveguide modes of a multi-mode resonator or waveguide, and to derive the desired fluid characteristics therefrom. The most preferred embodiment is a dual-mode coupled resonator filter geometry with one resonant mode having a high degree of symmetry and the other having a high degree of anti-symmetry. By combining the additional information of multi-moded operation with the inherent ability of a horizontally-polarized quasi-shear-horizontal acoustic wave device (AWD) to operate in fluid environments, one obtains a multi-mode quasi-shear-horizontal (MMQSH) resonator.
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Citations
23 Claims
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1. A method of measuring at least two fluid properties selected from density, viscosity, and elastic modulus, when the third of said fluid properties is known or assumed, the method comprising the steps of:
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providing a Multi Mode Quasi Shear Horizontal Resonator (MMQSHR) having an energy input, and a measuring surface for contacting said fluid, said measuring surface having at least a first region and a second region, and a separation area defined therebetween; feeding said MMQSHR with excitation energy via said input, at a first and a second frequencies selected to excite a first and a second acoustic modes respectively, each of said acoustic modes causing a component of horizontal shear wave motion in said surface, wherein excitation in said first frequency further causing said regions to move in phase relative to each other; and wherein excitation in said second frequency causes said two regions to move out-of-phase relative to each other, inducing a vertical displacement in said separation area; measuring energy related parameters at said first mode and second mode; calculating two of said fluid properties utilizing said energy related parameters and information relating to said third fluid property. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 20)
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14. A system for measuring at least two fluid properties selected from density, viscosity, and elastic modulus, when the third of said fluid properties is known or assumed, the system comprising:
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A Multi-Mode Quasi Shear Horizontal (MMQSHR) resonator having a measuring surface for contacting said fluid; an energy input port and an energy output port; at least a first region and a second region, and a separation area defined therebetween; excitation circuitry coupled at least to said energy input, and constructed to impart two acoustic modes of resonant motion to said surface; wherein said two acoustic modes are selected to cause differing amplitudes of motion normal to said surface, when excited at the resonant frequency of said different acoustic modes; measurement circuitry constructed to measure at least one parameter of the energy inputted into the MMQSHR resonator or outputted therefrom; and
,parameter calculating processor coupled to said measurement circuitry, and constructed to calculate at least said two fluid properties when said third fluid property is known or assumed. - View Dependent Claims (15, 16, 17, 18, 19)
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21. A resonator comprising a region of added mass defining trapped energy region, said trapped energy region supporting a plurality of laterally confined modes, said modes interacting with at least one transducer, said transducer providing electrical impedance relating to energy loss in said trapped energy resonator.
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22. A fluid parameter measurement system comprising:
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a biasing magnetic field; an oscillating magnetic field; a resonator comprising; at least a conducting surface region; an energy trapping structure for placement within said biasing and oscillating magnetic fields, wherein said oscillating magnetic field causes eddy currents within said conducting surface region; said eddy currents interacting with said biasing magnetic field, creating a time-harmonic force field within said resonator; and
wherein said force field imparts quasi shear horizontal acoustic waves at a surface of said resonator, said acoustic wave having at least a first and a second frequency respectively;said first frequency selected to cause at least a first region of said surface, and a second region of said surface to move in phase relative to each other, said first and second regions having a first separation area interspersed therebetween; said second frequency selected to cause a third region of said surface and a fourth region of said surface to move out of phase relative to each other, said first and second regions having a second separation area interspersed therebetween, wherein imparting energy to cause resonance at said second frequency induces a vertical displacement in said second separation area; said system further comprises a tracker constructed to track the displacement of selected regions of said surface. - View Dependent Claims (23)
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Specification