Abstract: The velocity of fluids containing particles that scatter ultrasound can be measured by determining the Doppler shift of the ultrasound scattered by the particles in the fluid. Measuring fluid flow in cylindrical vessels such as blood vessels is an important use of Doppler ultrasound. This invention teaches using various configurations of cylindrical diffraction-grating transducers and cylindrical non-diffraction-grating transducers that suppress the Doppler shift from non-axial components of fluid velocity while being sensitive to the Doppler shift produced by axial velocity components. These configurations thus provide accurate measurement of the net flow down the vessel, even when the fluid flow is curved or not parallel to the vessel wall.

Abstract: Ultrasound diffraction-grating transducers produce beams at an angle to their face, which makes them useful for Doppler measurement of scattering fluids such as blood. The present invention discloses a diffraction-grating transducer, with the capability to focus transmitting or receiving beams to a desired point in space. This focusing capability leads to greater sensitivity when the diffraction-grating transducer is used as a receiver, and greater concentration of ultrasound energy when used as a transmitter. The focusing is achieved by using curved elements instead of the straight ones in conventional diffraction-grating transducers, and by using non-uniform spacing among these elements rather than the uniform spacing of conventional diffraction-grating transducers. Methods of computing the proper curvature of the elements and their spacing for a desired focal point in space are provided.

Abstract: Matching layers improve the performance of ultrasonic transducers. Such layers have traditionally required significant effort and expense to be added to ultrasonic transducers. The present invention discloses a method of producing ultrasonic transducers with a matching layer, specifically for ultrasonic transducers utilizing piezopolymer transducer materials. Rather than the conventional method of forming the piezopolymer on a substrate and then attaching a matching layer through which the transducer emits its ultrasound energy, we teach depositing the piezopolymer on a substrate that also serves as a matching layer through which the ultrasound is emitted. We also teach depositing an additional shield layer for reducing electromagnetic interference. Methods of how to select materials and modify their ultrasonic characteristics are also discussed.

Abstract: Matching layers improve the performance of ultrasonic transducers. Such layers have traditionally required significant effort and expense to be added to ultrasonic transducers. The present invention discloses a method of producing ultrasonic transducers with a matching layer, specifically for ultrasonic transducers utilizing piezopolymer transducer materials. Rather than the conventional method of forming the piezopolymer on a substrate and then attaching a matching layer through which the transducer emits its ultrasound energy, we teach depositing the piezopolymer on a substrate that also serves as a matching layer through which the ultrasound is emitted. We also teach depositing an additional shield layer for reducing electromagnetic interference. Methods of how to select materials and modify their ultrasonic characteristics are also discussed.

Abstract: The velocity of fluids containing particles that scatter ultrasound can be measured by determining the Doppler shift of the ultrasound scattered by the particles in the fluid. Measuring fluid flow in cylindrical vessels such as blood vessels is an important use of Doppler ultrasound. This invention teaches using various configurations of cylindrical diffraction-grating transducers and cylindrical non-diffraction-grating transducers that suppress the Doppler shift from non-axial components of fluid velocity while being sensitive to the Doppler shift produced by axial velocity components. These configurations thus provide accurate measurement of the net flow down the vessel, even when the fluid flow is curved or not parallel to the vessel wall.

Abstract: Matching layers improve the performance of ultrasonic transducers. Such layers have traditionally required significant effort and expense to be added to ultrasonic transducers. The present invention discloses a method of producing ultrasonic transducers with a matching layer, specifically for ultrasonic transducers utilizing piezopolymer transducer materials. Rather than the conventional method of forming the piezopolymer on a substrate and then attaching a matching layer through which the transducer emits its ultrasound energy, we teach depositing the piezopolymer on a substrate that also serves as a matching layer through which the ultrasound is emitted. Methods of how to select materials and modify their ultrasonic characteristics are also discussed.

Abstract: Matching layers improve the performance of ultrasonic transducers. Such layers have traditionally required significant effort and expense to be added to ultrasonic transducers. The present invention discloses a method of producing ultrasonic transducers with a matching layer, specifically for ultrasonic transducers utilizing piezopolymer transducer materials. Rather than the conventional method of forming the piezopolymer on a substrate and then attaching a matching layer through which the transducer emits its ultrasound energy, we teach depositing the piezopolymer on a substrate that also serves as a matching layer through which the ultrasound is emitted. Methods of how to select materials and modify their ultrasonic characteristics are also discussed.

Abstract: The velocity of fluids containing particles that scatter ultrasound can be measured by determining the Doppler shift of the ultrasound scattered by the particles in the fluid. Measuring fluid flow in cylindrical vessels such as blood vessels is an important use of Doppler ultrasound. This invention teaches using various configurations of cylindrical diffraction-grating transducers and cylindrical non-diffraction-grating transducers that suppress the Doppler shift from non-axial components of fluid velocity while being sensitive to the Doppler shift produced by axial velocity components. These configurations thus provide accurate measurement of the net flow down the vessel, even when the fluid flow is curved or not parallel to the vessel wall.

Abstract: Transducers to measure fluid flow using Doppler ultrasound that are suitable for integrating into or connecting to intravascular devices are disclosed. These transducers meet the requirement for long, thin, flexible transducers, and consist of one or more diffraction-grating transducers, with or without non-diffraction-grating transducers. An exemplary configuration of the transducers utilizes the diffraction caused by narrow transducers to produce beam overlap for Doppler detection of moving blood, and stripline transmission lines are used to bring energy to and receive energy from the transducers and may carry the disclosed transducer configurations as well as carry signals into and out of the blood vessels.

Abstract: A system for monitoring blood flow confined by at least one vessel wall, the system including: at least one implantable diffraction-grating transducer being embedded within or adjacent to a vessel wall, the diffraction-grating transducer being suitable for emitting ultrasound into or receiving Doppler shifted ultrasound from the blood flow; and, a source for pulse-exciting the implantable diffraction grating; wherein, the Doppler shift is indicative of the blood flow.

Abstract: A dual spiral transducer and method of manufacture of same is disclosed. In one aspect, the transducer comprises a central rod, a first spiral piezoelectric electrode wrapped around a circumference of the rod, the electrode being advanced around the rod at a determined angle determined based on a length of a single complete turn around the rod and a diameter of the rod and a second spiral piezoelectric electrode wrapped around the circumference of the rod, the second spiral electrode being electrically isolated, and offset, from the first spiral electrode by a known distance. A second set of spiral electrodes can be integrated into the structure so that both transmission and reception of signals is feasible.

Abstract: An ultrasound system provides Doppler spectral data indicative of a monitored moving fluid. The spectral data is analyzed according to the level of power in specified Doppler frequency ranges. Audio signals indicative of each analyzed range are generated to enable a user to audibly determine said range is in order to detect a certain condition manifested by said fluid motion.

Abstract: A dual spiral transducer and method of manufacture of same is disclosed. In one aspect, the transducer comprises a central rod, a first spiral piezoelectric electrode wrapped around a circumference of the rod, the electrode being advanced around the rod at a determined angle determined based on a length of a single complete turn around the rod and a diameter of the rod and a second spiral piezoelectric electrode wrapped around the circumference of the rod, the second spiral electrode being electrically isolated, and offset, from the first spiral electrode by a known distance. A second set of spiral electrodes can be integrated into the structure so that both transmission and reception of signals is feasible.

Abstract: An apparatus and method for detecting the highest velocity of fluid flow with in a volume having multiple sources of fluid flow with different velocities. There are multiple pairs of receiving transducers arranged about a region wherein each transducer in a pair is positioned on the same axis with respect to the region. A transmitting transducer is positioned at the region to provide an output frequency signal, which frequency signal is transmitted to the fluid flow area volume. This causes Doppler shifted frequency signals to be reflected, with the Doppler shift being a function of the fluid flow velocity. Each of the receiving transducers receive the Doppler shifted signals. Signal processing means are responsive to the Doppler shifted signals and the original transmitted output frequency signal to process those signals to provide a velocity signal for each pair of transducers. One then selects the maximum velocity signal obtained from the pair.