950 results about "Acoustic impedance" patented technology

The invention is directed biopsy site markers and methods of marking a biopsy site, so that the location of the biopsy cavity is readily visible by conventional imaging methods, particularly by ultrasonic imaging. The biopsy site markers of the invention have high ultrasound reflectivity, presenting a substantial acoustic signature from a small marker, so as to avoid obscuring diagnostic tissue features in subsequent imaging studies, and can be readily distinguished from biological features. The several disclosed embodiments of the biopsy site marker of the invention have a high contrast of acoustic impedance as placed in a tissue site, so as to efficiently reflect and scatter ultrasonic energy, and preferably include gas-filled internal pores. The markers may have a non-uniform surface contour to enhance the acoustic signature. The markers have a characteristic form which is recognizably artificial during medical imaging. The biopsy site marker may be accurately fixed to the biopsy site so as to resist migration from the biopsy cavity when a placement instrument is withdrawn, and when the marked tissue is subsequently moved or manipulated.

In one embodiment the invention comprises a particle velocity sensor that includes a housing with a geophone mounted in the housing. A fluid that substantially surrounds the geophone is included within the housing. The particle velocity sensor has an acoustic impedance within the range of about 750,000 Newton seconds per cubic meter (Ns / m3) to about 3,000,000 Newton seconds per cubic meter (Ns / m3). In another embodiment the invention comprises method of geophysical exploration in which a seismic signal is generated in a body of water and detected with a plurality of co-located particle velocity sensors and pressure gradient sensors positioned within a seismic cable. The output signal of either or both of the particle velocity sensors or the pressure gradient sensors is modified to substantially equalize the output signals from the particle velocity sensors and the pressure gradient sensors. The output signals from particle velocity sensors and pressure gradient sensors are then combined.

Ultrasonic waveguides having improved velocity gain are disclosed for use in ultrasonic medical devices. Specifically, the ultrasonic waveguides comprises a first material having a higher acoustic impedance and a second material having a lower acoustic impedance.

A method and system for monitoring physiological parameters is useful for remote auscultation of the heart and lungs. The system includes an acoustic sensor (105) that has a stethoscopic cup (305). A membrane (325) is positioned adjacent to a first end of the stethoscopic cup (305), and an impedance matching element (335) is positioned adjacent to the membrane (325). The element (335) provides for acoustic impedance matching with a body such as a human torso. A microphone (315) is positioned near the other end of the stethoscopic cup (305) so as to detect sounds from the body. A signal-conditioning module (110) is then operatively connected to the acoustic sensor (105), and a wireless transceiver (115) is operatively connected to the signal-conditioning module (110). Auscultation can then occur at a remote facility that receives signals sent from the transceiver (115).

A piezoelectric resonator with an acoustic Bragg reflector that includes alternating layers of high and low acoustic impedance materials. The high and low acoustic impedance dielectric materials make up electrically insulating layers.

A component operating with bulk acoustic waves has two Bulk Acoustic Wave (BAW) resonators that are stacked and are acoustically coupled to one another, with a first resonator being connected to an asymmetric port, and a second resonator being connected to a symmetrical port. The acoustic coupling is provided by a partially permeable coupling layer system, which has an alternating sequence of at least two λ / 4 mirror layers with different acoustic impedance. The coupling layer system furthermore has a compensation layer, which has an approximate thickness of λ / 8. The compensation layer according to the invention makes it possible to match any discrepancy in the phase difference (which is caused by reflections on the mirror layers) from the predetermined 180° between the connections of the symmetrical port to approximately 180°.

Method for forming, by means of an inversion technique, a model of an underground zone, constrained by static data: data obtained by seismic exploration or measured in situ (logs), and by dynamic data: production measurement, well testing, etc. From an a priori selected meshed geologic model and from relations between parameters or physical quantities characteristic of the medium: acoustic impedance and cabsolute permeability for example, a simultaneous inversion of the two parameters is performed by minimizing a global cost function, which has the effect of considerably decreasing the number of possible solutions and of improving characterization of the underground zone. The method can be used notably for modelling hydrocarbon reservoirs, of zones likely to be used as gas, waste storage places, etc.

A system for improving the acoustic performance of an ultrasound transducer by reducing artifacts within the acoustic spectrum is disclosed. The system includes an acoustic layer having an array of acoustic elements, a dematching layer coupled to the acoustic layer and having an acoustic impedance greater than an acoustic impedance of the acoustic layer, and an interposer layer coupled to the dematching layer and comprising a substrate and a plurality of conductive element. The interposer layer is formed to have an acoustic impedance lower than the acoustic impedance of the dematching layer. The ultrasound transducer also includes an integrated circuit coupled to the interposer layer and electrically connected to the array of acoustic elements through the dematching layer and the interposer layer.

A piezoelectric resonator that achieves stable quality and improved resonance characteristics includes an acoustic reflector portion disposed between a substrate and a vibration portion, which includes a piezoelectric thin film sandwiched between a pair of electrodes, and a plurality of low acoustic impedance layers made of a material having relatively low acoustic impedance and a plurality of high acoustic impedance layers formed made of a material having relatively high acoustic impedance, the acoustic impedance layers being disposed alternately, and adjustment layers, which are disposed between the high acoustic impedance layers and the low acoustic impedance layers on the substrate sides of the high acoustic impedance layers and which have an acoustic impedance value intermediate between that of the high acoustic impedance layers and that of the low acoustic impedance layers. The low acoustic impedance layers and the high acoustic impedance layers have compressive stresses and the adjustment layers have a tensile stress.

An acoustic wave resonator device comprising a resonant layer that comprises a series of side-by-side areas of first and second dielectric materials. In one embodiment the first dielectric material is a piezoelectric, in particular the first dielectric material can be a piezoelectric and the second dielectric material can be non-piezoelectric. In another embodiment, the first dielectric material is a piezoelectric of first polarity and the second dielectric material is a piezoelectric of opposite polarity or different polarity. Where needed, the resonant layer is supported on a reflector composed of series of layers of high acoustic impedance material(s) alternating with layers of low acoustic impedance material(s). For example, the reflector comprises AlN, Al2O3, Ta2O5, HfO2 or W as high impedance material and SiO2 as low impedance material.

An elastic wave device propagating plate waves includes a stack of an acoustic reflection layer, a piezoelectric layer, and IDT electrode on a supporting substrate. The piezoelectric layer is thinner than a period of fingers of the IDT electrode. The acoustic reflection layer includes low-acoustic-impedance layers and high-acoustic-impedance layers. The low-acoustic-impedance layers are made of SiO2, and the high-acoustic-impedance layers are made of at least one material selected from the group consisting of W, LiTaO3, Al2O3, AlN, LiNbO3, SiN, and ZnO.

A high-bypass gas turbine engine includes a variable area fan nozzle with an acoustic system having an acoustic impedance.

An ultrasonic transducer device comprising: an ultrasonic transducer array micromachined on a substrate; flexible electrical connections connected to the transducer array; and a body of acoustically attenuative material that supports the substrate and the flexible electrical connections. The acoustic backing material may contain additional features, such as tabs or notches, for use in positioning the transducer on fixtures during manufacturing or positioning the transducer within a housing during final assembly. Tabs or other features that are used only during manufacturing may be subsequently removed from the device. The MUT device itself may also be thinned so as to provide flexibility as desired. The backing material is preferably matched in acoustic impedance to the silicon wafer so as to prevent reflection at the interface of any acoustic energy propagating rearward, i.e., in the direction away from the device front surface. The backing material may also possess a high thermal conductivity to assist in removal of heat from the device.

Acoustic shielding system and method for protecting and shielding non-targeted regions or tissues that are not intended to be treated by ultrasonic procedures from acoustic energy using a shield. In some embodiments, the shield comprises multiple layers made of one or more materials with one or more acoustic impedances. In some embodiments a multilayered shield includes materials with relatively different acoustic impedance levels. In some embodiments, the shield includes active components such as energy diversion devices, heating, cooling, monitoring, and / or sensing. In some embodiments, the shield is configured to protect an eye, mouth, nose or ear while allowing the ultrasound to treat the surrounding tissue. One embodiment of an eye shield is configured to fit under at least one eyelid and over a portion of the eye.

PCT No. PCT / GB97 / 00263 Sec. 371 Date Jul. 8, 1998 Sec. 102(e) Date Jul. 8, 1998 PCT Filed Jan. 30, 1997 PCT Pub. No. WO97 / 27770 PCT Pub. Date Aug. 7, 1997A protective material and a method for the protection of the human head or body from soft tissue damage caused by an impacting object comprises at least two layers of viscoelastic polymeric material to be interposed between head or body and impactor, including at least one first layer of material substantially matched in acoustic impedance to the impacting object and at least one second layer of material selected to produce a large mismatch in acoustic impedance between the first layer and the human head or body. A particular aspect applies the invention to head protection, especially in boxing and like sports, in the form of boxing head guards and boxing gloves.