Showing papers on "Transducer published in 1988"

Diffuse focus ultrasound hyperthermia system

Abstract: A system for delivering ultrasound hyperthermic therapy to a subject includes a plurality of piezoelectric ultrasound transducer elements arranged in a two-dimensional array to provide multiple sources of ultrasonic energy, and variable activation elements for activating the transducer elements individually and at variable electrical energy levels. A plurality of lens elements is provided for transmitting the multiple sources of ultrasonic energy to the subject, in conjunction with focusing elements which individually vary the attitude of the lens elements to change the focal regions of the individual lenses. The transducer elements and lens elements can be corresponding "pie-slice" sectors arranged in a circular array, in combination with a central circular transducer and lens.

An ultraminiature solid-state pressure sensor for a cardiovascular catheter

Abstract: An ultraminiature solid-state capacitive pressure sensor that can be mounted in a 0.5-mm OD catheter suitable for multipoint pressure measurements from within the coronary artery of the heart is described. The transducer consists of a silicon 290*550*1.5- mu m/sup 3/ microdiaphragm surrounded by a 12- mu m-thick silicon supporting rim, both defined by the boron etch-stop technique. The transducer process features a batch wafer-to-glass electrostatic seal followed by the silicon etch, which eliminates handling of individual small diaphragm structures until die separation and final packaging. A hybrid interface circuit chip provides a high-level output signal and allows the sensor to be compatible with use on a multisite catheter having only two leads. >

Electronically-controlled variable focus ultrasound hyperthermia system

Abstract: A therapeutic ultrasound hyperthermia system utilizes a phased array of ultrasound transducer elements. By varying the phase delays in the excitation of individual transducer elements, the focal depth of the ultrasonic beam can be varied, without changing the distance between the transducer and the patient. The phased array of transducer elements can be an array of rectangular elements which are rotated about an axis to deliver ultrasound to the target region while minimizing overall heating effect in the treatment areas outside the target region.

Device and method for measuring volumetric blood flow in a vessel

Abstract: Device for measuring volumetric blood flow in a vessel comprising a catheter having proximal and distal extremities. A balloon is carried by the distal extremity of the catheter. A balloon inflation lumen is carried by the catheter and is in communication with the balloon. A toroidal ultrasonic transducer is carried by the catheter and is spaced proximally of the balloon. Electrical circuitry is provided for supplying electrical energy to the transducer. The transducer produces a large substantially uniform beam of ultrasonic energy to illuminate a vessel of approximately three centimeters in diameter with the ultrasonic energy.

Electroacoustic transducer of the so-called "electret" type, and a method of making such a transducer

Abstract: This invention provides an electroacoustic transducer and a method of making it. The transducer according to the invention comprises a substrate of a semiconductor material with a recessed portion. A membrane is stretched across the recessed portion, which membrane is set in vibration in response to an input signal comprising audio and/or ultrasonorous frequencies. A pair of electrodes is provided, which form a capacitor, and between which an electric field is present. The electrodes are so arranged relatively to the membrane that the capacitance of the capacitor can vary under the influence of vibrations of the membrane, so that acoustic signals are converted into electric signals. A layer of an electrically insulating material functions as a carrier for an electric charge to provide an auxiliary electric field between the electrodes. The transducer is characterized in that the peripheral edge of the substrate, which is raised relatively to the recessed portion, has a set of openings formed in it, each extending through the substrate. The membrane is attached through the openings to the peripheral edge.

Ultrasound imaging probe with zero dead space

Abstract: An ultrasonic imaging probe includes a probe guide assembly, an ultrasonic transducer fixed to the distal end of the probe guide assembly, and electrical cabling housed within the probe guide assembly and operatively connected to the transducer for sending electrical pulse/signals to/from the transducer. The transducer is of a type which emits/receives ultrasonic waves along a path parallel to the elongate axis of the probe. The ultrasonic waves are directed radially of the probe by means of a reflector element which is distally spaced from the transducer along the probe's axis by a dimension sufficient to remove "dead space"(i.e., an area where ultrasonic imaging is not possible) radially of the catheter. An inductor coil (which tunes the transducer to the electrical cabling) is coaxially housed within the probe guide assembly closely adjacent the transducer and is electrically connected in series thereto. By removing the dead space radially of the catheter tube and by mounting an inductor coil closely adjacent the transducer within the probe guide assembly, a miniaturized ultrasonic imaging probe is provided which is especially useful for intravascular imaging/diagnostic procedures.

A high frequency stray-immune capacitance transducer based on the charge transfer principle

Abstract: A stray-immune capacitance measuring instrument based on the charge transfer principle is described. It has a programmable measurement frequency up to several megahertz and is inexpensive and suitable for integration onto a single chip. The effects of stray capacitances, including those of the switching components, have been eliminated by using a special switching arrangement, resulting in a baseline drift of 0.02 pF (at 1-MHz measurement frequency) over a 12-h period. >

Ultrasonic cleaning apparatus with phase diversifier

Abstract: A wedge-shaped vibration-transmitting plate is located between the bottom wall of a cleaning tank and an ultrasonic transducer which is operable to produce vibratory energy in a liquid bath in the tank. The wedge-shaped plate diversifies the phase of initially in-phase energy waves produced by the transducer and causes waves of different phase to propagate upwardly through the liquid. As a result of the phase diversification, the concentration of high and low power levels at various depths in the bath is reduced so that cleaning action over the span of the vertical dimension is more uniform. In addition, the overall action of wave reflection at the upper surface of the bath fluctuates through a smaller range when the depth of the bath changes. This enables the transducer to be energized with a more stable input power.

Simple piezoelectric translation device

Abstract: We describe a piezoelectric device which allows continuous movement and high‐resolution micropositioning, without distance limitation. Both mechanical construction and the electronics for the device are very simple. The movement is obtained via a stick‐slip mechanism, and steps as small as 10 nm are obtained. A displacement speed of 0.4 mm/s has been attained, and the device was capable of carrying several times its own weight, exerting a horizontal force, or climbing a plane inclined by 7°. Due to its compact construction, the device shows prospects for miniaturization.

Time-resolved investigations of laser-induced shock waves in water by use of polyvinylidenefluoride hydrophones

Abstract: Laser light from a Q‐switched Nd:yttrium‐aluminum‐garnet laser (λ=1064 nm; pulse duration=20 ns; pulse energies up to 150 mJ) focused into water creates shock waves by rapidly expanding microplasmas. Using piezoelectric, thin‐film polyvinylidenefluoride (PVDF) as a transducer, a broadband hydrophone (100‐MHz bandwidth) was developed to investigate underwater shock waves. The electrical signal is analyzed with respect to reflections of the shock wave within the transducer and the input impedance of the measuring device. The shock waveform is determined, its peak pressure ranging to kbars (108 Pa), decreasing with r−1.12 and increases by the square root of the laser pulse energy. The time resolution of the hydrophone (4 ns) is sufficient to determine the plasma dimensions and the number of shock waves generated by a single laserpulse. Both vary statistically, primarily because of contaminations in the fluid. Because of the length of the region containing plasmas, different peak pressures are found in the di...

Megasonic cleaning apparatus

Abstract: A transducer array for use in a megansonic cleaning system including a transmitter element made of a material which will efficiently transmit megasonic energy when bonded to one conductive surface of a transducer. In one form, the transmitter and the transducer are flat plates. In another form, a flat transducer is bonded to a solid semi-cylindrical transmitter which causes the megasonic energy pattern to diverge. In another form, the transmitter is a semi-cylindrical shell or is tubular, and the transducer is bonded to and curved to conform to the transmitter. The transducer extends about 120°, and produces a straight line of sight diverging energy pattern.

Method and apparatus for coherent imaging system

Abstract: A method and apparatus for improved digital processing of the analog echo signals in a coherent imaging system is described which simplifies the channel circuitry requirements. The analog echo signals detected with a phased array of transducer elements are first compressed in a non-linear manner then expanded non-linearly with analog-to-digital converter means to provide increased instantaneous dynamic range in the overall system. Representative phased array coherent imaging systems having the improved digital processing means are also disclosed.

Ultraminiature pressure sensor and method of making same

Abstract: A capacitive pressure sensor suitable for making highly sensitive, low pressure measurements is disclosed. The sensor may be mounted into a 0.5 mm OD catheter suitable for multipoint pressure measurements from within the coronary artery of the heart. The sensor employs a transducer which consists of a rectangular bulk silicon micro-diaphragm several hundred microns on a side by two microns thick, surrounded by a supporting bulk silicon rim about 12 microns thick. Both the diaphragm and the rim are defined by a double diffusion etch-stop technique. The transducer fabrication process features a batch wafer-to-glass electrostatic seal followed by a silicon etch, which eliminates handling of individual small diaphragm structures until die separation and final packaging. An addressable read-out interface circuit may be used with the sensor to provide a high-level output signal, and allows the sensor to be compatible for use on a multisite catheter having only two electrical leads.

Medical device for ultrasonic treatment of living tissue and/or cells

Abstract: The invention contemplates an ultrasonic body treatment system wherein a body applicator is self-contained unit with its own radio-frequency oscillator/driver, factory-pretuned to its own transducer. A remote-control unit supplies control signals via optical coupling to the oscillator-driver of the body-applicator unit. Another optical coupling from the body-applicator unit to the remote-control unit enables fidelity of applicator performance to be monitored at the remote-control unit. A safety interlock at the body-applicator unit precludes transducer operation in the absence of adequate coupling to a patient's body. The remote-control unit can thus provide all supervisory and control functions for the body-applicator unit without any electrical interconnection between these units.

Magnetic disk drive with low profile head-suspension system

Abstract: Docket No. R0986-023 MAGNETIC DISK DRIVE WITH LOW PROFILE HEAD-SUSPENSION SYSTEM ABSTRACT OF THE DISCLOSURE The magnetic data storage system includes a magnetic transducer head-suspension assembly with an inline suspension slider with a reduced height leading portion that provides for gimballed connection to the suspension load beam and a full height rear portion that enables the use of the increased height portion for the transducer coil windings. The suspension includes a single piece combined gram form and load beam with the entire head-suspension assembly being contained within the height of the slider full height portion to enable minimization of the head-suspension overall height required in magnetic-disk drives with closely spaced disks and back to back transducer heads or minimum height head-suspension assemblies that extend between disk surfaces.

Motion artifact detection for continuous blood pressure monitor transducer

Abstract: A method and apparatus is provided for detecting motion artifacts in data obtained from a blood pressure monitoring transducer and for preventing erroneous data related to such artifacts from interfering with the accuracy of the blood pressure measurement. Operation includes the steps of monitoring the amplitude of a pulse waveform from a first pulse to a next successive pulse and determining if the output signal changes by more than a predetermined percentage, thus indicating a motion condition.

Ruby decay‐time fluorescence thermometer in a fiber‐optic configuration

Abstract: In this article, a fluorescence decay‐time thermometer using ruby crystal as the transducer material and carefully designed signal processing, with a light‐emitting diode source and solid‐state optical detection is reported. Results over a range to 170 °C are discussed with a standard deviation in the measurement, at best, corresponding to ±0.04 K, in laboratory tests.

Absolute capacitance manometers

Abstract: A single fluid-pressure transducer unit, of the type in which sensed electrical capacitance is varied in accordance with electrode deflections induced by pressure changes, is rendered capable of characterizing a wide range of pressures extending from near-vacuum to atmospheric levels, with the aid of a distinctive composite-electrode capsule which interacts uniquely with a conventional type of sheet-metal diaphragm. While sensing relatively low pressures, the exhibited capacitance of the transducer is essentially that appearing between the diaphragm and a nearby electrode carried by the capsule, but, at or near atmospheric pressure, the diaphragm physically engages and deflects that electrode, which is elastically deformable, causing it to vary a further capacitance appearing between that deformable electrode and a companion stationary electrode which is also part of the capsule.

Solid state vibrating gyro

Abstract: An angular rate sensor is formed of a transducer and associated electronics. The transducer consists of two parallel beams with attached proof masses, which are angularly vibrated about respective proof masses center of gravity in a first plane. Rotation of the gyro about its input axis results in Coriolis moments causing vibration in a plane normal to the first plane. A torque is applied to restrain the vibration of the proof masses to the first plane. A voltage proportional to this torque is demodulated and filtered and output as a voltage proportional to the angular input rate.

High resolution proximity detector employing magnetoresistive sensor disposed within a pressure resistant enclosure

Abstract: A tachometer sensor adapted for measuring the rotation of a gear or spline shaft target within a high pressure environment includes an integrally formed housing having a generally tubular elongate probe defining a sealed interior cavity receiving an annular permanent magnet at the sensing end thereof, field focusing means such as a ferrous pin disposed concentrically with the permanent magnet to shape the field established thereby, at least one magnetoresistive transducer concentrically disposed with the magnet to detect distortions of the magnetic field effected by passage of the target and means in-circuit with the transducer which generates a usable output signals as a function of sensed magnet field distortion.

In vivo and in vitro ultrasound beam distortion measurements of a large aperture and a conventional aperture focussed transducer

Abstract: Ultrasound focussing through human tissue of thicknesses varying from 10 mm to 35 mm has been measured for two transducers with diameters 50 mm and 19 mm both focussed at 50 mm (f/1 and f/2.6, respectively). Comparisons are made between the two-way focal depth beam patterns obtained in water and those obtained after passage through tissue to study the degrading effects of frequency-dependent attenuation and inhomogeneities, and their dependence on aperture size. The effects of frequency-dependent attenuation is to broaden the beam and shorten the focal distance. Inhomogeneities mainly increase the sidelobe levels and cause deviations from the central beam axis. A direct comparison of the beam patterns of the two transducers after passage through the same tissue samples shows that the resolution is improved by using the larger aperture. The use of the larger transducer in the in vitro measurements on three human liver specimens demonstrated an average improvement in the −6 dB beamwidth, over the smaller transducer, of 42% (standard deviation ± 3%). The average improvement in the in vivo measurements on ten female breasts was 34% (standard deviation ±5%). The measured improvement in water was 52%. Therefore, the measured resolution improvement in tissue is approximately 2 3 of that obtained in water. The results indicate that for an f/1 transducer with a focal depth of 50 mm the upper limit of maximum useful aperture size has not been reached.

Sonar fish finder apparatus providing split-screen display

Abstract: A sonar fish finder system is provided for a boat for determining and displaying the location of fish in the body of water surrounding the boat. The system includes an electromechanical transducer assembly for transmitting sound waves in the body of water along separate paths in different directions into separate areas of the body of water, for receiving corresponding echoes from obstructions in the paths (including echoes from any fish in the paths) and for generating electrical signals in accordance with the received echoes. Electrical transmitters connected to the transducer assembly control transmission of the sound waves and receivers, connected to the transducer assembly, receive and process the electrical signals produced thereby. A microprocessor unit converts the output of said receivers into electrical data representative of display images of the separate areas of the body of water and a visual display device, preferably a liquid crystal display, simultaneously displays images corresponding to the electrical data at separate side by side locations on a screen to provide separate, simultaneous indications of the presence or absence of fish in the different areas.

Electro-acoustic transducer

Abstract: An electro-acoustic transducer, such as a speaker device or an earphone device. Includes an electro-acoustic transducing unit, such as a speaker unit, for converting input electrical signals into sound, a casing in which the electro-acoustic transducing unit is arranged and which delimits a back cavity towards the rear side of the electro-acoustic transducing unit, and at least two openings having a sound duct communicating with the back cavity. The sound radiated from the back surface of the electro-acoustic transducing unit is attenuated by being transmitted into the inside of the sound duct to prevent the radiated sound from being re-admitted into the electro-acoustic transducer.

Focussing ultrasound transducer

Abstract: A focussing transducer for the destruction of objects internal to a patient's body by pulses of ultrasonic waves The transducer comprises a concave transducer surface which is divided into areas and there is a control means which can selectively activate the areas of the transducer so that the waveform arriving at the focus can adjusted

Composite piezoelectrics: Basic research to a practical device

Abstract: The adaptability of 1–3 PZT-rod/polymer-matrix piezoelectric composites commends them for the requirements of medical ultrasonic imaging transducers. We describe material fabrication techniques, material design considerations, and transducer design trade-offs involved in this application. A simple dice-and-fill fabrication technique yields material suitable for transducers with frequencies approaching 10 MHz. The piezocomposites provide high electromechanical coupling and low acoustic impedance – properties superior to those of the conventional piezoceramics and piezopolymers. Composite piezoelectric plates can be formed into complex shapes for beam focusing and steering. Moreover, arrays defined by simply patterning the electrode – not cutting the plate – exhibit no spurious modes in individual elements and low cross-talk between array elements. The resulting device performance is illustrated with a concave annular array which shows high sensitivity (8 dB insertion loss), large bandwidth (57%), ...

A dive parameter indicating assembly

Abstract: A dive parameter transmitter/receiver assembly for scuba diving is described. The assembly has a transmitter circuit (90) with a control unit with one or more sensors (P1, P2, T, D) for detecting dive parameters and/or information to be displayed. A modulator (101) is included for modulating the parameter(s) or information and a transmitting transducer (99) for propagating the parameter(s) or information. A receiver circuit (70) is included and has a receiver transducer (71), a demodulator (75), a decoder (76) and a display (86, 87) for displaying the parameter(s) or information.

The Accelograph®: a new neuromuscular transmission monitor

Abstract: A new neuromuscular transmission monitor based on measurement of acceleration is presented. The monitor consists of an acceleration transducer, i.e. a piezo-electric ceramic wafer with an electrode on each side, and a stimulation and computing unit. The transducer can be fastened to the thumb, and when the finger is moved in response to nerve stimulation a voltage difference develops between the two electrodes. The voltage is then measured and registered in the computing unit. The acceleration transducer does not require preload, but merely that the muscle on which the measurement is being made can move freely. The accelograph is therefore easy to set up and operate. In daily clinical practice it has proved possible, using this new apparatus, to achieve reliable evaluation of the degree of non-depolarizing neuromuscular blockade in less than 2 min.

Programmable sensor apparatus

Abstract: A user-programmable sensor system for generating an alarm signal upon detection of an alarm event is disclosed. The system is particularly suited for use in vehicle security systems. The system employs a three axes accelerometer as a shock/motion detector, and the transducer outputs are summed and the composite signal filtered to provide several channels, each covering a specific frequency or frequency band. The outputs of the channels are digitized and processed by a microprocessor. An event is characterized by seveal signal parameters with an alarm event triggered by the simultaneous occurrence of several predetermined conditions, and not just one condition. The limit values for the signal parameters which are required to qualify a shock/motion event as an alarm event may be readily programmed by the user at any time or place. The system further includes a glass breakage transducer and analyzes higher frequency components of the transducer signal to sense a glass breakage event when predetermined signal parameters are exceeded and when energy from the shock detector correlates with the glass breakage signal. The correlation with several parameters substantially reduces false alarm signals resulting from ambient high frequency noises, such as caused by passing siren-sounding vehicles or low-flying jets or helicopters.

Potential-magnetic energy driven valve mechanism

Abstract: A bistable electronically controlled transducer having an armature reciprocable between first and second positions is disclosed including either a stressed spring or compressed air within a closed chamber in the transducer for causing the armature to move, and a permanent magnet latching arrangement for holding the armature in either one of the positions. An electromagnetic arrangement for temporarily neutralizing the effect of the permanent magnet latching arrangement releases the armature to move from one to the other of the positions. The transducer finds particular utility as an actuator mechanism for moving internal combustion engine valves.

Method and apparatus for sensing fluid flow volume to indicate end of filter life

Abstract: A method and solid-state electronic flowmeter with no moving parts is provided for monitoring instantaneous and/or accumulated fluid flow. A preferred application for the method and flowmeter is the measurement of the total volume of filtered fluid in a fluid treatment system as an indication of end of life for a filter therein. The flowmeter employs a solid-state transducer which senses differential pressure generated by a flow restriction such as a venturi which varies depending on a rate of flow. The transducer output in integrated over time to provide a representation of total fluid flow through the filter. The meter is preferably compact and battery-powered to facilitate ease of installation and use. Battery power is conserved by periodically energizing the transducer during idle periods and by periodically energizing the end of life indicator during and end of life condition.