Showing papers on "Transducer published in 1992"

Intravascular imaging apparatus and methods for use and manufacture

Abstract: A device for ultrasonic imaging, and methods for the use an manufacture thereof, particularly of small coronary vessels. The device comprises an elongate member with a distal end that can be positioned within a small vessel of a patient's body while a proximal end is located outside the body, a transducer located at a distal end of the elongate member and operable to scan the distal coronary vessels with ultrasonic pulses, and a signal processor connected to a proximal end of the elongate member and to the transducer for generating and receiving pulses to and from the transducer. A motor may be also connected to the proximal end of the elongate member for rotating the transducer.

Ultrasonic surgical apparatus

Abstract: An electrical apparatus for driving an ultrasonic piezoelectric crystal transducer in a surgical handpiece for the fragmentation and aspiration of tissue, which apparatus includes an electronic control loop (12) in combination with a voltage source amplifier (2) having an output which is connected to the piezoelectric crystal transducer (3) with a tuning inductor (4) in parallel. A control system for monitoring the control loop (12) and a component for controlling tissue selectivity are also disclosed.

Apparatus and method for intra-cardiac ablation of arrhythmias

Abstract: The present invention employs ultrasonic energy delivered to myocardial tissue at frequencies sufficient to destroy the myocardial tissue implicated in the arrhythmic. More specifically, the present invention comprises an ultrasonic transducer mounted on a distal end of a catheter and at least one electrode associated with the distal end region of the catheter. The ultrasonic transducer may be a single crystal transducer or a phased array crystal transducer.

Electromagnetic midsagittal articulometer systems for transducing speech articulatory movements

Abstract: This paper describes two electromagnetic midsagittal articulometer (EMMA) systems that were developed for transducing articulatory movements during speech production. Alternating magnetic fields are generated by transmitter coils that are mounted in an assembly that fits on the head of a speaker. The fields induce alternating voltages in a number of small transducer coils that are attached to atriculators in the midline plane, inside and outside the vocal tract. The transducers are connected by fine lead wires to receiver electronics whose output voltages are processed to yield measures of transducer locations as a function of time. Measurement error can arise with this method, because as the articulators move and change shape, the transducers can undergo a varying amount of rotational misalignment with respect to the transmitter axes; both systems are designed to correct for transducer misalignment. For this purpose, one system uses two transmitters and biaxial transducers; the other uses three transmitters and single‐axis transducers. The systems have been compared with one another in terms of their performance, human subjects compatibility, and ease of use. Both systems can produce useful midsagittal‐plane data on articulator movement, and each one has a specific set of advantages and limitations. (Two commercially available systems are also described briefly for comparison purposes.) If appropriate experimental controls are used, the three‐transmitter system is preferable for practical reasons.

Method and apparatus for ultrasound imaging and atherectomy

Abstract: A catheter for ultrasonic imaging has a transducer fixed to a cutter. The transducer is moved longitudinally within an artery while in a fixed radial position. Ultrasonic reflections are received and processed to display a planer or rectangular field of view image area of the artery. Other axial planes of the artery can be imaged by radially turning the transducer to a different angular orientation within the artery and then longitudinally moving the transducer to obtain an image of another planer field of view.

Device and method for monitoring breathing during sleep, control of CPAP treatment, and preventing of apnea

Abstract: A CPAP apparatus including: a variable pressured air source and means to vary the air pressure delivered therefrom; a nose piece for sealed air communication with a patient's respiratory system; an air communication line from the air source to the nose piece; a sound transducer adapted to be in sound communication with the patient's respiratory system; and a feedback system controlling the output pressure of the air source in response to an output from the transducer so as to increase the output air pressure from said air source, in response to detection of sound indicative of snoring, in accordance with a predefined procedure. The sound transducer, in its most general form, comprises a pressure transducer which, in addition to detecting snoring sounds, can detect other respiratory parameters such as the rate of breathing, inhaled air flow volume, and inhaled air flow rate. Output air pressure from air source is increased in response to one or more of these parameters in accordance with a pre-defined procedure.

Mechano-electrical transducer currents in hair cells of the cultured neonatal mouse cochlea.

Abstract: The first step towards the generation of the receptor potential in hair cells is the gating of the transducer channels and subsequent flow of transducer current, induced by deflection of the stereocilia We describe properties of the transducer current in outer hair cells of neonatal mice Less extensive observations on inner hair cells suggest that their transducer currents have similar characteristics The hair bundles were stimulated by force from a fluid jet The transducer currents in outer hair cells are the largest found so far in any hair cell, with a chord conductance of up to 92 nS at -84 mV The transfer function suggests that the channel has at least two closed states and one open state The permeabilities for sodium, potassium and caesium are similar, consistent with the channel being a fairly non-selective cation channel At negative potentials the currents adapt in most cells, although never as completely as in hair cells of lower vertebrates If the unit conductance of the transducer channel is similar to that of the turtle's auditory hair cells (100 pS), then there are about 90 channels per hair bundle, or one channel between every pair of adjacent stereocilia in neighbouring rows

Ultrasonic position indicating apparatus and methods

Abstract: An ultrasonic imaging system employs a processing circuit which enables the imaging system to accurately display the location of an element in a body by utilizing a transducer which provides an electric signal when an ultrasonic wave impinges thereon. The electric signal is processed to determine the maximum amplitude signals during an entire frame of the ultrasonic imaging system. The signals are characterized in terms of the line at which the signal appears or the ray at which the signal appears and the pixel or location along that line. This information regarding ray and pixel serves as X-Y coordinates enabling one to accurately locate the element and transducer on the displayed image by intensifying the display at that location or by adding color or by producing some other visual effect such as blinking, and so on. Thus the disclosed apparatus in its various forms provides ultrasonic position indication without adjustment whereby one shows the exact location of the localizing transducer.

Electromechanic transducer for implantable hearing aids

Abstract: Electromechanical transducer for implantable hearing aids. The transducer has a hermetically sealed and biocompatible housing, in which a wall is designed as a membrane that can oscillate, and which forms a heteromorphic connecting element together with a piezoelectric ceramic disk. Mechanical oscillations of the housing membrane are coupled to the middle ear or inner ear of the user by a mechanically rigid element attached in the central area of the membrane. This element is configured as a bow, so that in positioning the transducer housing from the direction of the mastoid adjoining the tympanic cavity, it acts as an artificial anvil to which coupling elements can be attached for mechanically transmitting oscillations of this artificial ossicle to the inner ear. Various coupling elements can be used, which correspond to the respective individual pathological situation. The application of the entire transducer system can be performed the operating surgeon having an unobstructed view, without extensive, space-creating interventions in the anatomical conditions of the middle ear.

Method and apparatus for elastographic measurement and imaging.

Abstract: An improved ultrasonic pulse-echo method and apparatus that has particular application in making precision measurements of compressibility in any backscattering material, in particular organic tissue, is disclosed. The method employs a standard transducer or transducer containing device which is translated transaxially, thereby compressing or displacing a proximal region of a target body in small known increments. At each increment, a pulse is emitted and an echo sequence (A-line) is detected from regions within the target along the sonic travel path or beam of the transducer. Resulting time shifts in echo segments corresponding to features in the target, corrected for regions of varying sonic speed along the sonic path, provide relative and quantitative information concerning the strain caused by the compressions. The stress imparted by the transducer and containing device is also determined, corrected for depth along the sonic path. The appropriate values for stress are divided into the respective values for strain along each path to yield an elastogram, or array of compressibility values, of the target.

Optimal vibration control by the use of piezoceramic sensors and actuators

Abstract: In this paper, a discrete degrees of freedom model has been formulated for a structural dynamic system consisting of a linear elastic structure, bonded piezoceramic sensors and actuators, and a feedback signal conditioning system. In addition, an optimal control procedure based on the minimization of a quadratic performance index of state and control vectors has been developed that uses output feedback methods. Finally, the application of the model and the control technique has been demonstrated through the example of a linear elastic beam with piezoceramic sensors and actuators occupying discrete subdomains of the beam upper and lower surfaces. A model for the linear elastic beam has been obtained by using test results and a structural dynamic system identification method based on an equation error approach. Results for various weights in the performance index are included, and implications for future applications are discussed. N the past few years, there has been considerable research activity in the field of active and passive control of vibra- tions of flexible structures. One of the methods of active con- trol of vibrations, termed "electronic damping" in some of the early literature,1'6 involves the placement of piezoceramic devices on a structure to sense and control dynamic strains induced by structural vibrations. The deformation of a sens- ing transducer results in an electrical current that is condi- tioned by operations such as amplification and shifting of the phase of the signal. The conditioned signal is then applied to another piezoceramic, electrostrictive, or magnetostrictive device placed at a selected location on the structure. This trans- ducer acts as an actuator and transmits mechanical energy to the structure. Depending on the applied voltage, electrome- chanical coupling of the forcing transducer to the structure, and the location of the transducers, a degree of vibration control of flexible structures can be achieved. To date, applica- tions of the aforementioned scheme have primarily been in the area of large space structures, such as in the work of Crawley and Deluis,7 but the scheme is applicable to any structure with lightweight components. This type of active control offers unique features that are not usually employed for control of structural vibrations. The dynamics of direct contact type sensors and actuators permit a wide frequency range of control. A measure of tunability is provided for the control of structural systems that age or grow. Finally, this method adds little mass to the controlled flexible structure so that the existing plant model does not need to be modified to account for the mass of the transducers. To utilize the advantages of piezoceramic transducers, it is necessary to select appropriate positions of the transducers and to select the sensor signals that are to be fed back to the actuators. The problem of selecting the locations of the transducers is a complete problem in itself and thus will not be addressed in this paper. There has been some work in

Acousting imaging catheters and the like

Abstract: Acoustic imaging balloon catheters formed by a disposable liquid-confining sheath supporting a high fidelity, flexible drive shaft which carries on its end an ultrasound transducer and includes an inflatable dilatation balloon. The shaft and transducer rotate with sufficient speed and fidelity to produce real time images on a T.V. screen. In preferred embodiments, special features that contribute to the high fidelity of the drive shaft include the particular multi-filar construction of concentric, oppositely wound, interfering coils, a pre-loaded torque condition on the coils enhancing their interfering contact, and dynamic loading of the distal end of the probe, preferably with viscous drag. The coil rotating in the presence of liquid in the sheath is used to produce a desirable pressure in the region of the transducer. Numerous selectable catheter sheaths are shown including a sheath with an integral acoustically-transparent window, sheaths with end extensions that aid in positioning, a liquid injection-producing sheath, a sheath having its window section under tension employing an axially loaded bearing, a sheath carrying a dilatation or positioning balloon over the transducer, a sheath carrying a distal rotating surgical tool and a sheath used in conjunction with a side-viewing trocar.

High efficiency bi-directional spatial power combiner amplifier

Abstract: The present invention is a high efficiency bi-directional spatial power combiner for extremely high frequency signals. In one embodiment, orthogonally polarized electro-magnetic waves are used to isolate signals going into and out of a planar array of amplifiers. A dual mode horn transmits vertically polarized fields to a MMIC planar array of amplifiers. Vertically polarized array elements receive the signals, amplify them, and retransmit back to the horn using horizontally polarized array elements. An ortho-mode transducer on the horn provides isolation for the two polarized signals. The backside of the array can be used for a heat sink, and to provide access for DC biasing of the array elements. In a second embodiment, monolithic grid oscillators are used in lieu of power amplifiers with orthogonal polarization array elements. The input signal and the output signal are of the same polarization. A circulator is used in lieu of an ortho-mode transducer to isolate the input signal from the output signal.

Synthetic aperture ultrasound imaging system

Abstract: An acoustical imaging system for producing high resolution medical images provides a method and apparatus for obtaining accurate velocity characterizations of samples within the human body, and for obtaining high resolution images of the samples by utilizing the velocity characterizations of the samples within the human body. The acoustical imaging system also provides a method and apparatus for efficient use of switching channels whereby for a transducer array having a plurality of transducer elements, a set of receiver channels which number less than the number of transducer elements in the array are assigned to a selected portion of the plurality of transducers in the array, wherein for any predetermined set of transducers symmetrically located about a selected transducer, the predetermined set equal in number to the number of receiver channels in the system, each receiver channel in the set of receiver channels is only assigned to one transducer in said predetermined sampling set.

Ultrasonic tool connector

Abstract: Disclosed is a mechanical junction (43, 45) for facilitating the rapid attachment and removal of ultrasonic surgical components (44, 46) for the transfer of ultrasonic energy across the junction (43, 45) from an ultrasonic transducer (42) to an ultrasonically activated tool bit (44). The junction (43, 45) achieves a high, evenly distributed compressive force to optimize propagation of the ultrasonic energy from the transducer (42) to a tool bit (44), while maintaining a ralatively small outside diameter of the ultrasonic tool (44, 46). Also disclosed are a plurality of ultrasonic energy activated tool tips (51, 200, 220, 240, 260, 280, 300, 320, 340, 360, 380, 400, 420, 440, 460, 480, 500, 520, 540, 560) for introducing and removing an orthopedic prosthesis.

Use of at least one composite piezoelectric transducer in the manufacture of an ultrasonic therapy apparatus for applying therapy, in a body zone, in particular to concretions, to tissue, or to bones, of a living being and method of ultrasonic therapy

Abstract: The invention relates to a composite piezoelectric transducer for making an acoustic or an ultrasonic therapeutic apparatus. The transducer may be a single large-size transducer or it may be a multi-transducer device and it advantageously emits ultrasonic waves that are focused on a focal point.

Ultrasonic transducers and transducer arrays for applications in air

Abstract: Many measurement tasks in industrial automation, e.g. non-contact distance measurement, room surveillance, object identification and gas flow measurement can be accomplished by sensors using airborne ultrasound. Their performance is determined by the properties of the ultrasonic transducers. The authors compare electrostatic and piezoelectric transducers. Piezoceramic transducers combine a high efficiency factor and ruggedness. Composite transducers consisting of piezoceramic and polymer materials show a wider relative bandwidth of about 30% at the expense of efficiency. Ultrasonic transducers based on piezopolymer foils offer a variety of acoustic properties at low expenditure. Their bandwidth corresponds to that of composite transducers. Composite, as well as piezopolymer, foil transducers are suited to the design of phased arrays. Foil transducers have the additional advantage of very small crosstalk between neighbouring transducer elements. By electronically controlled deflection of the sound beam, lateral details and consequently the spatial structure of objects can also be detected.

Control system for calibrating and driving ultrasonic transducer

Abstract: An electronic control system for determining the resonant frequency of and driving ultrasonic transducers in a phacoemulsification probe used for ophthalmic surgery. The control system includes a voltage control led oscillator, power amplifier, power monitor, and automatic gain control circuit operating under the direction of command signals received from a microprocessor-based control console. The control system operates in a constant apparent power, direct drive mode with closed loop feedback maintaining the electrical power provided to the primary of a RLC transformer at the constant level requested by the command signals from the console. The frequency of the drive signal is held at the dominant resonant frequency of the ultrasonic transducer which is being driven by the control system. This resonant frequency is determined via a calibration procedure performed when the probe is first attached to the control system. During this procedure a constant voltage drive signal is swept through a range of frequencies and the electrical power consumed by the transducer is measured and stored at selected intervals such as 100 Hertz increments. The resonant frequency is also determined in part by looking for the frequency at which maximum power is consumed by the probe. The stored data is also subjected to other tests to check that the peak is indeed a resonant frequency and that the probe has selected output power characteristics about this resonant frequency, thus helping to ensure that the probe is capable of operating satisfactorily when driven by the control system.

Digital beamforming in ultrasound

Abstract: The effects on array gain and sidelobe level of a practical digital beamforming (DBF) processor under the wideband conditions typical of ultrasound is discussed. It is concluded that a relatively simple design that replaces each analog delay line with a tapped, digital shift register (DSR) and a digital phase shift operation adjusted for midband will provide the desired performance, provided that the sampling rate of the signal at the input to the DSR is 4 to 10 times the bandwidth. More realistically, when nonidealized passbands are taken into account and the typical condition whereby the transducer frequency is about twice the bandwidth is considered, the rule of thumb for the sampling rate is that it must be 4 to 10 times the transducer frequency. >

An integrated mass flow sensor with on-chip CMOS interface circuitry

Abstract: A multielement monolithic mass flow sensor which developed for possible use in automotive and industrial process control applications is reported. The chip illustrates the use of a common microstructure (a thin dielectric window/diaphragm) for the simultaneous measurement of flow velocity (rate), flow direction, gas type, and pressure. These transducers are merged with on-chip interface electronics to amplify and multiplex the transducer signals, control on-chip actuators, perform self-test, reduce the number of external leads required, and demonstrate process compatibility with a p-well CMOS process. The on-chip circuitry also implements a bandgap sensor for the measurement of ambient temperature. Thus, the chip simultaneously monitors all parameters needed for the computation of true mass flow, requires only ten external leads, and delivers high-level buffered output signals. >

Catheter for laser treatment of atherosclerotic plaque and other tissue abnormalities

Abstract: A medical catheter (10) for treating atherosclerotic plaque (16) and other abnormalities includes optical fibers (30) for applying laser energy to the plaque (16) and an ultrasonic transducer system (32, 34) for sensing the location and configuration of the plaque (16). The optical fibers (30) and electrical wiring (40) for the transducers (32, 34) extend through a probe (28) which is rotatable inside of the catheter tube (12) to provide universal directional control of the fibers (30) and transducers (32, 34). A reflective system includes a curved reflector (38) in the probe (28) which can be axially adjusted to vary the directions of the ultrasonic signals. Alternative forms of the invention include different reflector schemes, an angled ultrasonic transducer (32, 34) having a conical signal output that varies with frequency, and various different systems for rotating the transducers (32, 34) and fibers (30).

Liquid level sensor

Abstract: The level of a liquid (14) is detected by an ultrasonic arrangement comprising a transmitter (10) and a receiver (12). The transmitter (10) has a vertical array of transmitter segments (16) which transmit sequentially, while the receiver (12) is a single transducer. The difference in transmission time in liquid and gas allows a digital, depth representative output to be generated. The transmitter (10) is formed by securing a single sheet (20) of piezo polymer film over a printed circuit board (24) having a conductive pattern defining the segments (16). Other embodiments provide analogue outputs, and non-linear outputs representative of volume in irregular tanks.

Mass flow meter

Abstract: A mass flow meter for flowing media that works on the Coriolis Principle has at least one essentially straight Coriolis pipeline carrying the flowing medium, with at least one oscillator acting on the Coriolis pipeline and with at least one transducer detecting Coriolis forces and/or Coriolis oscillations based on Coriolis forces. Measuring errors or mechanical damage due to temperature fluctuations and outside forces and torques are minimized or eliminated by providing a compensation cylinder, and arranging the Coriolis pipeline inside the compensation cylinder.

Self-sensing piezoelectric actuation - Analysis and application to controlled structures

Abstract: Issues related to modeling and implementation of a self-sensing piezoelectric actuator are investigated The necessary formulation for modeling the simultaneous sensing and actuation phenomenon is provided Open and closed loop experiments performed on a cantilevered beam test specimen are described The sensitivity of the results to representative errors introduced in the implementation of the transducer is demonstrated analytically and experimentally The self-sensing actuator is also implemented using an active piezoelectric strut in a truss structure

Multiplane Transesophageal Echocardiography: Latest Evolution in an Imaging Revolution

Abstract: Multiplane imaging with a rotating phased-array transducer from within the esophagus represents the latest development in transesophageal cardiac ultrasound. Transverse, longitudinal, and all possible intermediate oblique planes are easily obtained from the same transducer with minimal probe manipulation. Three-dimensional conceptualization of complex structures and pathologic conditions is facilitated. The major advantages are a simplified examination procedure and much less patient discomfort than monoplane and biplane probe imaging.

Apparatus and method for forward looking volume imaging

Abstract: A scanning system that is forward looking that uses ultrasound for intraluminal imaging. A transducer that emits ultrasonic signals is nutatably mounted on the tip of a probe. The front mounted transducer enables intraluminal scanning of an oncoming area or volume as the probe moves to a selected position in a lumen or body cavity. Cables are used to nutate the transducer so as to provide spiral or raster scanning patterns. The cables are driven by programmable electromagnetic drives. Three dimensional images are then obtained from the reflected ultrasonic signals.

Hermetically sealed implantable transducer

Abstract: A hermetically sealed acoustic mechanism for an implantable hearing aid system having a signal processing unit having at least one electromechanical transducer coupled to the auditory system of a human. The transducer having an outer casing and at least one moving member extending outside the casing. The invention comprising a hermetically sealed bellows member having two ends and a generally cylindrical side wall. One end of the bellows member being hermetically affixed to the transducer casing and the other end of the bellows member being hermetically affixed to the moving member at a point outside the transducer casing. The side wall having a plurality of corrugations formed therein to allow the moving member to vibrate independently from the transducer casing while providing a hermetic seal protecting the interior of the transducer.

Vehicle proximity sensor

Abstract: A vehicle sensing system includes a data bus, a first microprocessor coupled to the bus and a plurality of sensor modules about a vehicle periphery for detecting the presence of objects within a predetermined range of distances of each of such sensor modules. Each sensor module of the vehicle sensing system includes a transducer, a second microprocessor, coupled between the transducer and the bus, for processing information received from the transducer, and a light emitting diode disposed on an outer surface of a housing for the transducer, coupled to the second microprocessor, for indicating when an object is within the predetermined distance of the sensor module or when the sensor module is faulty. Each sensor module further includes a temperature sensing circuit coupled to the second microprocessor and a bus transceiver for receiving information from the bus and for transmitting information to the bus.

A nebuliser and nebuliser control system

Abstract: A nebuliser for use in administering a medicament to a patient undergoing treatment for example, comprises an ultrasonic piezoelectric transducer (60) and a transducer drive system (D) which is caused to drive said transducer at or near its anti-resonant frequency. There is also provided means to optimise nebulised fluid particle size and transfer to the patients lungs for example, by operating at an anti-resonant frequency in the range of 1.36 to 1.56 MHz and having a single outlet baffle and relatively short outlet tube (24) arrangement.

Electronic monitoring unit for monitoring number of uses of cartridge

Abstract: A self-contained electronic monitoring unit for attachment to a device, such as a water filter, designed to be used until the occurrence of a predetermined event such as a predetermined number of uses, includes transducer for providing distinct outputs such as different audio output signals. A programmed integrated circuit and use detecting means such as electrical contacts detect each use of the device and monitor when the device is operational, when the end of life event is imminent and has occurred. The integrated circuit is programmed to operate the transducer to produce output signals during each use of the device informing the user that the device is operational, that the predetermined event or end of useful life is imminent and that the useful life has expired. The unit includes a battery for supplying power to the transducer and integrated circuit.