Double-sided fluid sensor for reduced attenuation of shear transverse waves
First Claim
1. A sensing device for use in testing with fluids comprising,a substrate adapted to propagate shear transverse waves, said substrate having opposed first and second surfaces, said second surface having a sensing region,an input means on said first surface for launching shear transverse waves, said waves having a tendency to diffract from the first surface into the bulk of said substrate,an output means on said first surface for receiving said waves,first wave-trapping means having a first section on said first surface for allowing increasing diffraction of waves into the bulk of said substrate with departure from said input means and having a second section for recapturing wave energy with approach to said output means,second wave-trapping means on said sensing region of said second surface for selectively tightening and relaxing trapping of said waves which are diffracting with said departure from said input means, said second wave-trapping means having a dimensional configuration to relax trapping of said waves for said recapturing of wave energy by said second section of said first wave-trapping means, andmeans for applying a fluid under test to said sensing region of said second surface.
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Abstract
A fluid sensing device such as a Surface Transverse Wave device or a Love Wave device having controlled transfers of energy from a transduction surface of a piezoelectric substrate to a sensing surface and back to the transduction surface. A first wave-trapping structure adjacent to an input transducer tapers to provide a controlled diffraction of shear transverse wave energy to a second wave-trapping structure disposed on an opposite side of the piezoelectric substrate. The second wave-trapping structure interfaces with the fluid under test. The shear transverse waves are then recaptured by a third wave-trapping structure on the same surface as the first wave-trapping structure. The wave energy is then decoupled from the piezoelectric substrate. In the STW device, the wave-trapping structures are periodic fingers that are selectively varied in thickness or width or both. In the LW device, the wave-trapping structures are plates that each vary in thickness.
49 Citations
17 Claims
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1. A sensing device for use in testing with fluids comprising,
a substrate adapted to propagate shear transverse waves, said substrate having opposed first and second surfaces, said second surface having a sensing region, an input means on said first surface for launching shear transverse waves, said waves having a tendency to diffract from the first surface into the bulk of said substrate, an output means on said first surface for receiving said waves, first wave-trapping means having a first section on said first surface for allowing increasing diffraction of waves into the bulk of said substrate with departure from said input means and having a second section for recapturing wave energy with approach to said output means, second wave-trapping means on said sensing region of said second surface for selectively tightening and relaxing trapping of said waves which are diffracting with said departure from said input means, said second wave-trapping means having a dimensional configuration to relax trapping of said waves for said recapturing of wave energy by said second section of said first wave-trapping means, and means for applying a fluid under test to said sensing region of said second surface.
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8. A Surface Transverse Wave device for use in testing with fluids comprising,
piezoelectric means for propagating shear transverse waves, said piezoelectric means having a substrate having opposed transduction and sensing sides, said piezoelectric means further having an input transducer on said transduction side to launch said waves and an output transducer on said transduction side to receive said waves, said input transducer spaced apart from said output transducer, means for applying a fluid to said sensing side of said substrate, first wave-trapping means on said transduction side of said substrate proximate to said input transducer for guiding transfer of wave energy from said transduction side to said sensing side, said first wave-trapping means including a first grating of fingers having heights and widths, at least one of said heights and widths varying from finger-to-finger so as to provide said guiding of wave energy, second wave-trapping means on said sensing side within a sensing region of said substrate to trap wave energy received from said input transducer on said transduction side, said second wave-trapping means including a second grating of fingers, and third wave-trapping means on said transduction side proximate to said output transducer for recapturing wave energy from said sensing side, said third wave-trapping means including a third grating of fingers having heights and widths, at least one of said heights and widths varying from finger-to-finger for said recapturing of wave energy.
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14. A Love Wave device for use in testing with fluids comprising,
piezoelectric means for propagating shear transverse waves, said piezoelectric means having a substrate having opposed transduction and sensing sides, said transduction side having an input transducer to launch said waves and an output transducer to receive said waves, said input transducer spaced apart from said output transducer, means for applying a fluid to said sensing side of said substrate, a first wave-trapping plate on said transduction side proximate to said input transducer, said first wave-trapping plate diminishing in thickness at a plate end opposite to said input transducer, a second wave-trapping plate on said sensing side for surface trapping of wave energy from said input transducer, and a third wave-trapping plate on said transduction side proximate to said output transducer, said third wave-trapping plate diminishing in thickness at a plate end opposite to said output transducer, said first and third wave-trapping plates being spaced apart.
Specification