Abstract: A method is provided for fabricating an annular ring transducers for determining the velocity of a fluid flow. A novel and accurate flow measurement system is fabricated for measuring transit time of a fluid flow using chirp signals, and a pneumotachometer with annular ring transducers is also disclosed.

Abstract: An accurate and reliable pneumotachometer with annular ring transducers for determining the velocity of a fluid flow is provided. A novel and accurate flow measurement system for measuring transit time of a fluid flow using chirp signals and a pneumotachometer with annular ring transducers is also disclosed.

Abstract: An accurate and reliable pneumotachometer with annular ring transducers for determining the velocity of a fluid flow is provided. A novel and accurate flow measurement system for measuring transit time of a fluid flow using chirp signals and a pneumotachometer with annular ring transducers is also disclosed.

Abstract: A technique for efficiently sampling blood from body tissue by reducing pressure on the body tissue. In the present technique a body tissue is placed under reduced pressure to improve perfusion of blood in the body tissue before lancing. An embodiment of this apparatus includes a lancet carried by a piston slidable in a housing, a mechanism for transmitting mechanical energy internally in the apparatus for creating the reduced pressure on the body tissue. The apparatus also includes a driver that drives the lancet for lancing. The apparatus has a head in the housing for contacting the body tissue in an air-tight manner against suction forces. In the head facing the body tissue is a channel in which the air pressure can be reduced.

Abstract: A direct contact scanner uses a fiber acoustic waveguide to convey ultrasound from an ultrasound transducer to a direct contact area. The waveguide extends from a main body of the scanner into an oblong nose, and terminates in a deflector. To minimize thickness of the nose, the waveguide and deflector are rotated about an ultrasound transmission axis of the waveguide, enabling the scanner to be used in a variety of situations where quarters are cramped. A coupling fluid conveys ultrasound between the deflector and a radome, which directly contacts the object to be scanned. Using the waveguide, an ultrasound transducer and supporting electronics may be distanced from the direct contact area and separated from the fluid, thereby insulating the fluid from possible electronic leakage currents and heat.

Abstract: A noninvasive blood chemistry measurement method and system isolate measurement contributions due to a patient's blood to accurately measure blood chemistry. In accordance with a first preferred embodiment of the present invention a noninvasive blood chemistry measurement method decreases the blood volume within a patient's body part relative to the normal blood volume in the body part and performs a baseline measurement. Blood volume is then increased and a second measurement is performed. Comparison of the second measurement to the baseline measurement isolates the measurement attributes of the patient's blood. In accordance with a second preferred embodiment of the present invention a noninvasive blood chemistry measurement system decreases blood volume by applying mechanical pressure to a body part. In accordance with a third preferred embodiment of the present invention, blood volume in the body part is decreased using a pressure cuff.

Abstract: A noninvasive blood chemistry measurement method and system isolate measurement contributions due to a patient's blood to accurately measure blood chemistry. In accordance with a first preferred embodiment of the present invention a noninvasive blood chemistry measurement method decreases the blood volume within a patient's body part relative to the normal blood volume in the body part and performs a baseline measurement. Blood volume is then increased and a second measurement is performed. Comparison of the second measurement to the baseline measurement isolates the measurement attributes of the patient's blood. In accordance with a second preferred embodiment of the present invention a noninvasive blood chemistry measurement system decreases blood volume by applying mechanical pressure to a body part. In accordance with a third preferred embodiment of the present invention, blood volume in the body part is decreased using a pressure cuff.

Abstract: A system and method for coupling acoustic energy within a waveguide provides highly efficient and sensitive acoustic energy generation and detection. In particular, an ultrasound angioplasty system is described which makes use of an end-fire array of ring transducers to produce highly directionalized sound within an acoustic waveguide. The transducers can be made circularly symmetric, and may be composed of multiple segments for generating sound waves in independent x and y spatial modes within the acoustic waveguide. Each ring transducer is optimally spaced 1/2.lambda..sub.L from its neighbor transducers, such that alternate transducers transduce 180-degrees out of phase, and may have their electrical end inverted for common drive, or for summing of transducer electrical outputs when the array is used as a detector.

Abstract: A system and method for coupling acoustic energy within a waveguide provides highly efficient and sensitive acoustic energy generation and detection. In particular, an ultrasound angioplasty system is described which makes use of an end-fire array of ring transducers to produce highly directionalized sound within an acoustic waveguide. The transducers can be made circularly symmetric, and may be composed of multiple segments for generating sound waves in independent x and y spatial modes within the acoustic waveguide. Each ring transducer is optimally spaced 1/2.lambda..sub.L from its neighbor transducers, such that alternate transducers transduce 180-degrees out of phase, and may have their electrical end inverted for common drive, or for summing of transducer electrical outputs when the array is used as a detector.

Abstract: An ultrasonic probe, such as a catheter, includes an array of electroacoustic transducer elements arranged about a central region, with each element having a radiating surface directed to define a first acoustic energy path having a component of direction that is toward the central region. That is, the elements are inwardly directed. Within the central region is an acoustic reflector that reflects the acoustic energy along a second path to an object to be imaged. In another embodiment, the transducer elements are directed to project acoustic energy generally parallel to the axis of the ultrasonic probe, with the acoustic reflector providing reflection for defining an interrogation beam.

Abstract: An apparatus for providing efficient transmission of a beam of acoustic wave between an ultrasonic transducer and a remotely located body under examination by the beam. The apparatus includes a housing having an interior arranged so that the ultrasonic transducer is disposed therein. A prism is acoustically coupled with the transducer and with an acoustic waveguide having a longitudinal dimension extending outwardly from the interior of the housing. The acoustic prism is fixedly coupled with a proximate portion of the waveguide so as to provide efficient transmission of the beam of acoustic waves between the prism and the waveguide. Accordingly, The beam of acoustic waves is transmitted from the transducer, through the prism, and along the longitudinal dimension of the waveguide, to a distal portion of the waveguide. The distal portion of the waveguide is inserted into a remotely located patient's body under examination.

Abstract: A method of forming an impedance matching layer of an acoustic transducer includes geometrically patterning impedance matching material directly onto a radiating surface of piezoelectric substrate. In one embodiment, the matching layer is deposited onto the piezoelectric substrate and photolithographic techniques are utilized to pattern the matching layer to provide posts tailored to better match the piezoelectric substrate to a medium into which acoustic waves are to be transmitted. A nominal layer of metal between the posts and the piezoelectric substrate improves the attachment of the matching material to the substrate. The nominal layer may be chrome-gold and the matching material may be copper. Typically, the radiating surface is the substrate front surface from which acoustic waves are directed into a medium of interest, e.g., water or human tissue.

Abstract: This invention is a magnetostriction transducer and an intraoperative probe for acoustic imaging. The magnetostriction transducer has a coil and a magnetostriction element deposited on a portion of the acoustic waveguide that is inserted inside the coil. The magnetic field of the coil threads into the magnetostriction element and, due to the alternating magnetic field, the magnetostriction element changes its length at a rate equal to the frequency of the magnetic field. These length changes excite, among others, longitudinal waves in the core of the acoustic waveguide. The intraoperative probe has an array of acoustic waveguides bonded together. Each acoustic waveguide in the intraoperative probe has a transducer, such as a magnetostriction transducer of a piezoelectric transducer, that couples acoustic signals into the acoustic waveguides.

Abstract: A catheter tip imaging probe varies the effective radius of resolution of an acoustic beam by translating the focal length. Varying the effective radius improves the resolution at any point of interest along the arterial walls. The focal length can be dynamically translated by deflecting either the transducer or the mirror in a conventional imaging probe.

Abstract: Spherical annulus piezoelectric transducers 62, 64 and spherical disc piezoelectric transducer 66 form a spherical shell having a radius of curvature R with a focal point 70 near the end of cladded-core acoustic waveguide 72. Each transducer 62, 64, 66 generates a bulk acoustic wave of a unique frequency and transmits it to focal point 70 where it enters core 74 of cladded-core acoustic waveguide 72. Alternatively, a conical annulus piezoelectric transducers 92, 116 on a prism 90 generate bulk acoustic waves of multiple discrete frequencies and focus them through cladding 75 and into core 74 of cladded-core acoustic waveguide 72. Surface acoustic waves of multiple discrete frequencies can be generated by multiple sets of curvilinear interdigital conductors 132, 134 on a piezoelectric substrate 122. The shape of curvilinear interdigital conductors 132, 134 focuses the surface acoustic waves at focal point 70 located near the end of acoustic waveguide 72.

Abstract: An ultrasound transducer for intravascular examinations comprises an interleaved series of eccentric elliptical electrodes disposed on the back face of a piezoelectric substrate that has been alternately poled in the thickness dimension. The back face of the transducer is coupled to air, while impedance-matching layers are on the front face of the transducer. The front face is concave spherical to provide a geometric focus. The electrodes are driven at an ultrasound frequency. This arrangement results in a longitudinal-mode ultrasound transmission through the front face of the transducer. The eccentricity of the electrodes precompensates for distortion imposed by a cylindrical window. The pitch (spacing) of the electrodes increases radially, reducing speckling in the ultrasound image. This transducer provides for high-frequency intravascular examinations, and thus correspondingly high-resolution images, without using impractically thin piezoelectric substrates.

Abstract: An intracavity ultrasound diagnostic probe has a fiber acoustic waveguide that guides acoustic signals generated by a piezoelectric transducer located outside the body, through a body cavity and to an imaging site within the body where they reflect back into the ultrasound diagnostic probe that guides them back to the piezoelectric transducer located at the proximal end of the waveguide. The intracavity ultrasound diagnostic probe has one or more acoustic waveguides that could be optical fibers.

Abstract: An ultrasound probe includes an ultrasound emitter and a turbine. In one embodiment, the ultrasound emitter is a reflective surface which reflects ultrasound signals generated by a transmitter. The reflective surface reflects the ultrasound signals so that reflected ultrasound signals exit the ultrasound probe. The turbine is connected to the reflecting means. Fluid flowing through the turbine causes the turbine to rotate the reflecting means so that the reflected ultrasound signals sweep an area surrounding the ultrasound probe.

Abstract: An Ultrasonic Catheter Guidance System which overcomes the inadequacies, dangers, and difficulties encountered by previously available medical guiding apparatus is disclosed. The present invention utilizes a novel technique for coupling ultrasonic energy into an optical fiber that can be used within a blood vessel of patient's body. The present invention includes a transducer [44] which is precisely located on a thin slab of piezoelectric material [10] that generates ultrasonic acoustic surface waves [62] that propagate on the surface [13] or within the bulk of the slab [10]. The transducer [44] may be selected from a set of the many novel alternative configurations that are disclosed in the specification and illustrated by the drawings. The operating power and frequency of the present invention can be predetermined by altering the configuration of the transducers [44].

Abstract: One or more acoustic fiber guides are used to carry certain modes of acoustic energy to the tip of a catheter. Using these fibers, reflected sound (Doppler Sound) measurements are made in a blood environment without the risk to the patient associated with the use of an electrical transducer at the distal end of the catheter. Due to the size reduction provided, the Doppler probe is suitable for monitoring the blood flow in the coronary arteries. Using this invention wherein sound is transported to the catheter tip, risk is reduced and the catheter is significantly less expensive, and therefore can be treated as disposable. By the addition of optical fibers tipped with specific dyes and excited by optical energy of appropriate wavelength, the catheter tip system can also be utilized simultaneously as a combined (integral) optical blood gas and pH monitor using optical fluorescence and an acoustic Doppler velocity transducer.