Showing papers on "Transducer published in 1996"

Dual mode ultrasonic surgical apparatus

Abstract: A single ultrasonic surgical apparatus (10) can provide a substantial cutting effect on tissue, a substantial coagulation effect on tissue, and an appropriate blend of simultaneous cutting and coagulation effects on tissue. The ultrasonic surgical apparatus (10) is comprised of a handpiece (11) which incorporates a transducer (14) and a surgical tool (16), a source of electrical energy (17), a controller (18), and a switch (19). The apparatus may be operated at two frequencies within the ultrasonic spectrum, where the first frequency (22) is selected at the low end of the spectrum for enhanced tissue cutting performance, and the second frequency (23) is approximately three times higher for enhanced tissue coagulation performance. The two frequencies may be operated selectively or concurrently, and may be independently adjustable as to amplitude. The transducer (14) may be composed of magnetostrictive or piezoelectric elements (20 or 21). The surgeon to set the desired amplitude of the mechanical vibrations. The transducer (14) is mounted within the handpiece (11) at a location that corresponds to a vibration node common to both the first frequency (22) and the second frequency (23). Also claimed is a method for use, including the steps of: developing an ultrasonic resonance at a first frequency (22); developing an ultrasonic resonance at a second frequency (23) which is approximately three times greater than the first frequency (22); resonating an ultrasonic transducer (14) at the first frequency (22) concurrently with the second frequency (23); and supporting the transducer (14) where the nodes of vibration at the first frequency (22) are substantially coincident with the nodes of vibration at the second frequency (23).

A surface micromachined electrostatic ultrasonic air transducer

Abstract: Airborne ultrasound has many applications such as, ranging, nondestructive evaluation, gas flow measurement, and acoustic microscopy. This paper investigates the generation and detection of ultrasound in air at a few MHz. Conventional plane piston lead zirconium titanate (PZT) based transducers perform poorly for this application due to the lack of proper matching layer materials. Electrostatic, or capacitive, transducers promise higher efficiency and broader bandwidth performance. The device structure in this work consists of a capacitor where one plate is a circular silicon nitride membrane coated with gold and the other is a rigid silicon substrate. By applying a voltage between the membrane and the silicon substrate, an electrostatic force is exerted on the membrane which sets it in motion, thus generating a sound wave in air. Presented here is an electrical equivalent circuit model for electrostatic transducers which is based on the early work of Mason (1942). The electrostatic transducers were designed and constructed for operation at 1.8 and 4.6 MHz. The transducers were fabricated using standard micromachining techniques. An optical interferometer was used to measure the peak displacement of the 1.8 MHz electrostatic transducer at 230 /spl Aring//V. A transmit-receive system was built using two electrostatic transducers. The system had a signal to noise ratio of 34 dB at a transducer separation of 1 cm. Each transducer had a 3-dB bandwidth of 20%, and a one-way insertion loss of 26 dB. There is excellent agreement between the measured device performance and theoretical predictions.

Ultrasonic beam focusing through tissue inhomogeneities with a time reversal mirror: application to transskull therapy

Abstract: Time reversal of ultrasonic fields allows a very efficient approach to focus pulsed ultrasonic waves through lossless inhomogeneous media. Time reversal mirrors (TRMs) are made of large transducer arrays, allowing the incident field to be sampled, time reversed, and reemitted. Time reversal method corrects for phase, amplitude, and even shape aberration and thus, is more efficient than time shift compensation techniques. However, this technique needs the knowledge of the Green's function of a dominant scatterer available in the medium. Aberration correction for ultrasonic hyperthermia could be achieved by combining TRM with an artificial acoustic source or sensor implanted inside the treatment volume. In this paper, time reversal method has been experimentally applied to the focusing through the skull bone. It is shown that the skull induces severe attenuation of ultrasound and reduces the efficiency of the time reversal approach. Then, an amplitude correction method is proposed to focus through an attenuating layer located close to the array. This method consists in inversing the amplitude modulation and then time reversing these signals. Finally, this method is combined with numerical backpropagation to compensate for an attenuating layer located some distance away from the transducer array.

Three-dimensional digital ultrasound tracking system

Abstract: A method and apparatus for simultaneous measurement of multiple distances by means of networked piezoelectric transducers Through the use of high frequency digital counters, the propagation delay between the activation of an ultrasonic transducer and the reception by similar transducers is quickly and accurately defined By alternating the duty cycle between transmit and receive modes, the system can track and triangulate the three-dimensional positions for each transducer

Focused ultrasound surgery system guided by ultrasound imaging

Abstract: A system employing ultrasound imaging as a method to localize a patient's tissue volume to be treated prior to applying therapeutic levels of ultrasound energy includes a therapy transducer for producing high-intensity fields that cause necrosis and an imaging transducer for producing high-quality ultrasound images. The therapy transducer is a spheroidal piezoelectric element and the imaging transducer is made up of a plurality of piezoelectric elements mounted in fixed relationship to the therapy transducer. The therapy transducer transmits a beam that is focused at a location in the tissue to be treated. The imaging transducer is then steered to produce successive receive beams which scan the tissue, including the tissue at the focal point of the pulsed therapy transducer. The image of the focal point is then superimposed on an image of the tissue to be treated obtained by B-mode imaging using the imaging transducer to transmit and then receive. Proper alignment of the focal point and the tissue to be treated ensures proper positioning of the therapy transducer relative to the patient.

Trailer communications system

Abstract: A trailer communications system (36) is provided. The system (36) includes a trailer transducer unit (22) for location on a trailer (12). A vehicle transducer unit (24) can be located on a vehicle (26, 28, 30) or a stationary object (32). The trailer transducer unit (22) and the vehicle transducer unit (24) may communicate information in the form of acoustic signals broadcast at an ultrasonic frequency in response to a predetermined event.

A 100-MHz ultrasound imaging system for dermatologic and ophthalmologic diagnostics

Abstract: A major design problem concerning high-frequency broad-band ultrasound imaging systems is caused by the strong dispersive attenuation of the tissue, which gives rise to images with inhomogeneous resolution and poor signal to noise ratio (SNR). To address the noise problem, strongly focused transducers with high energy density in a narrow focal region are utilized, which also provide more isotropic images due to improved lateral resolution. To account for the short depth of the focal area two suitable imaging conceptions are used: 1) synthetic aperture concept and 2) B/D-scan concept. To avoid the inhomogeneity of the images, different transmitter signals for each depth are applied, which are pseudoinversely prefiltered according to the transfer function of the tissue. To gain signal energy required for inverse filtering, a pulse compression technique with nonlinearly frequency modulated chirp signals is utilized. These procedures have been implemented in an ultrasound imaging system, which has been developed in the authors' laboratory for eye and skin examinations, It can be used with transducers in a frequency range from 20 to 250 MHz.

Implantable and external hearing systems having a floating mass transducer

Abstract: A floating mass transducer for improving hearing in a hearing impaired person is provided. The floating mass transducer (100) may be implanted or mounted externally for producing vibrations in a vibratory structure of an ear. In an exemplary embodiment, the floating mass transducer comprises a magnet assembly (12) and a coil (14) secured inside a housing (10) which is fixed to an ossicle of a middle ear. The coil is more rigidly secured to the housing than the magnet. The magnet assembly and coil are configured such that conducting alternating electrical current through the coil results in vibration of the magnet assembly and coil relative to one another. The vibration is caused by the interaction of the magnetic fields of the magnet assembly and coil. Because the coil is more rigidly secured to the housing than the magnet assembly, the vibrations of the coil cause the housing to vibrate. The vibrations of the housing are conducted to the oval window of the ear via the ossicles. In alternate embodiments, the floating mass transducer produces vibrations using piezoelectric materials.

Experimental demonstration of a fiber Bragg grating accelerometer

Abstract: We report a fiber Bragg grating transducer for the measurement of acceleration. Results obtained using interferometric wavelength-shift detection demonstrate a demodulated signal output range of 50-g rms with a minimum detectable signal of /spl sim/1 mg//spl radic/Hz.

The excitation of Lamb waves in pipes using dry-coupled piezoelectric transducers

Abstract: The development of a dry-coupled piezoelectric transducer system for the detection of corrosion in chemical plant pipework using cylindrical Lamb waves is described. It is shown that the axisymmetricL(0,2) mode at a frequency of about 70 kHz is an attractive mode to use for longdistance propagation. The results show that a ring of piezoelectric length-expander elements can be used to excite theL(0,2) mode and to suppress all the nonaxisymmetric modes. Tests have been carried out both with the piezoelectric elements bonded to the pipe and fabricated into a simple transducer which was clamped against the pipe. The performance of the dry-coupled system was very similar to that of the bonded elements. In pulse echo tests, the noise floor obtained with the dry-coupled system was less than 1% of the amplitude of the propagatingL(0,2) mode. The drycoupled transducers provide a simple, light, readily detachable system for the long-range inspection of pipework.

Enhanced accuracy of three-dimensional intraluminal ultrasound (ILUS) image reconstruction

Abstract: A method for imaging an organ or internal structure within a body to obtain three-dimensional reconstruction of the organ or internal structure. The method includes steps of providing an intraluminal ultrasound imaging system capable of obtaining echographic images of the surrounding of a catheter imaging tip located inside the body of a patient, and a catheter tracking system comprising at least one ultrasound transducer mounted adjacent the imaging tip of an intraluminal ultrasound catheter for insertion into a patient, a plurality of transducers located away from said intraluminal ultrasound catheter so as to form a reference frame, and circuitry for calculating positions of the plurality of frame transducers relative to each other and positions of said catheter tip transducers relative to said plurality of frame transducers. The intraluminal ultrasound catheter imaging tip is positioned within a region of interest inside the body of the patient and a plurality of echographic images are obtained during deliberate movement or pull-back of the catheter, each image corresponding to an echographic data set. The position of the catheter axis with respect to each echographic data set obtained during pull-back is recorded. The position, and optionally the velocity of the catheter tip are recorded. The recorded position of the catheter tip can be used to calculate a catheter pull-back trajectory in three-dimensional space. The images are stacked around the catheter pull-back trajectory by positioning the origin of a first image at a first recorded position, and positioning subsequent images at their respective distances from the first image, wherein each echographic data set is positioned so that the catheter axis is aligned with the catheter pull-back trajectory.

Ultrasonic transducers and arrays

Abstract: Ultrasonic imaging is one of the most important and still growing diagnostic tools in use today. To better understand transducer/array performance and some of the factors that prevent ultrasonic imagers from reaching higher resolution, this article reviews past achievements and current developments in the technology, including piezoelectric materials, transducer/array fabrication and design, and modeling. It is concluded that the array or transducer is a crucial part of an ultrasonic imaging system. Although much progress has been made in recent years to improve performance, it is still a limiting factor in preventing ultrasonic imaging systems from reaching their theoretical resolution. Investigations into novel piezoelectric materials, array stack architecture design, and modeling are being pursued. In the future, it is likely that multidimensional arrays will gradually replace linear arrays as the industry standard.

A commercial solution for surface plasmon sensing

Abstract: A novel, fully integrated surface plasmon resonance (SPR) transducer is described which is based on the encapsulation of the required electro-optical components within the optical material, through a molding process. Prototype sensors based on this approach have been successfully fabricated and tested. Results are shown for sensing of refractive index variations in alcohol solutions. Additionally, the SPR transducer is shown to function as a biological sensor.

Therapy and imaging probe and therapeutic treatment apparatus utilizing it

Abstract: The therapy and imaging probe of the invention comprises a probe body (20') of an elongate shape defining a general axis (X--X), one imaging transducer (40') for transmitting imaging waves, and one therapy transducer (30') for transmitting therapy waves. The imaging transducer is mounted on first support means providing translational movement of the imaging transducer within the probe, parallel to the general axis (X--X) of the probe, between a withdrawn position and an extended position. The therapy transducer is mounted on second support means providing rotation of the therapy transducer within the probe, about an axis of rotation (X1--X1) parallel to the general axis (X--X) of the probe but offset with respect to the imaging transducer, to allow rotation of the therapy transducer between a withdrawn position and a treatment position. In the withdrawn or non-active position of the therapy transducer, the imaging transducer may be brought by translational movement to its extended position to occupy the place occupied by the therapy transducer in its treatment position. Thus, the imaging transducer may form an image of a region for treatment by the therapy transducer. In the treatment position of the therapy transducer, the imaging transducer is at its withdrawn position. The therapy transducer, during the transmission of therapy waves, directly transmits the therapy waves in a direction substantially identical to the direction in which the imaging transducer transmits the imaging waves when imaging waves are being transmitted.

An ultrasound indentation system for biomechanical properties assessment of soft tissues in-vivo

Abstract: An ultrasound indentation system for biomechanical assessment of soft tissues in vivo was developed. The pen-size, hand-held probe was composed of an ultrasound transducer and a load cell. The ultrasound transducer was at the tip of the probe serving also as the indentor. The thickness and deformation of the soft tissue layer were determined from the ultrasound echo. A compressive load cell was connected in series with the ultrasound transducer to record the force response. A validation experiment was performed on porcine tissues. Force and deformation acquired with the present system was in good comparison with those obtained from a Housfield material testing machine. Material constants were obtained via a curve-fitting procedure by predicting the force transient response from the deformation-time data using a quasilinear viscoelastic model. In addition, deformation in the fat and in the muscle could be differentiated. The potential applications of this type of indentation probes are many. The specific application of this current development is for stump tissue assessment in the design of prosthetics.

High resolution intravascular ultrasound transducer assembly having a flexible substrate

Abstract: An ultrasound transducer assembly of the present invention includes a flexible circuit to which an ultrasound transducer array and integrated circuitry are attached during fabrication of the ultrasound transducer assembly. The flexible circuit comprises a flexible substrate to which the integrated circuitry and transducer elements are attached while the flexible substrate is in a substantially flat shape. The flexible circuit further comprises electrically conductive lines that are deposited upon the flexible substrate. The electrically conductive lines transport electrical signals between the integrated circuitry and the transducer elements. After assembly, the flexible circuit is re-shapable into a final form such as, for example, a substantially cylindrical shape.

Electronic component and method of production thereof

Abstract: An electronic device and a fabricating method for fabricating the electronic device, the electronic device comprising; a surface acoustic wave device 3 having a main surface thereon having a transducer portion 4 and wiring patterns 5 connected electrically to the transducer portion; a printed circuit board 1 having wiring patterns 2 formed at least on one main surface thereof; a plurality of conductive bumps 6 which connect electrically both of the mutually opposed wiring patterns and form a space portion 10 between the surface acoustic wave device 3 and a printed circuit board 1; and resin portion 11 which, by heating/melting and hardening, makes an intimate contact with other main surface of the device and coats the device 3 and seals the device 3 together with the printed circuit board 1, wherein, by employing a highly thixotropic and viscous thermo-setting resin compared with a conventional one, an electronic device having a simple structure can be provided and fabricating process for fabricating the electronic device can be simplified.

Head suspension having reduced torsional vibration

Abstract: A transducer suspension for a drive system has a beam which is bendable in a vertical direction for holding the transducer adjacent to the media, but is torsionally stiff for quicker access times and reduced noise and errors. This inherently contradictory performance occurs by joining a laterally elongated brace which is torsionally stiff about its elongated dimension across a pair of laterally disposed strips to cause the strips to flex in unison, allowing bending but reducing torsional motion in the suspension about an axis which is substantially perpendicular to the torsionally stiff axis of the brace. The torsionally stiff brace may take the form of a tube having a rectangular, triangular or circular cross-section, and may be formed of material cut from the suspension to define the hinge strips. The brace may have reduced longitudinal dimensions at the connections to the strips to further filter torsional versus bending vibrations. A plurality of braces joined to hinge portions may also occur in a single suspension for increased effect.

Ultrasound transducer array with transmitter/receiver integrated circuitry

Abstract: An ultrasonic transducer assembly is disclosed having both transmit and receive circuitry integral to the transducer assembly for generating and receiving ultrasonic pulses. The ultrasonic transducer array which is integral with the transducer assembly preferably includes multi-layer transducer elements as transmit elements of the array and may include single layer transducer elements as receive elements. Also disclosed is an ultrasonic scanner utilizing the transducer assembly with integral transmit and receive circuitry to reduce the amount and complexity of interconnections between the transducer assembly and a scanner rack.

High density giant magnetoresistive transducer with recessed sensor

Abstract: A magnetic transducer employs a giant magnetoresistive sensor (18) whose sensing surface is separated by a dielectric layer (20) from a magnetically recorded surface carrying recorded data signals to be read back by the transducer. The dielectric layer (20) serves to protect the sensing layer from corrosion, electrostatic discharge from the record surface, mechanical damage from asperities, thermal asperities from heating resulting from close contact between the transducer and the record surface, and damage from exposure during lapping operations. This structure also reduces the readback pulse width and offtrack assymmetry, and improves servo linearity, thereby increasing recording density. The reduced signal amplitude is compensated for by the use of a giant magnetoresistive transducer with an intrinsically large output. The use of the recessed transducer reduces saturation of the transducer due to the record medium flux at reduced signal amplitudes, thereby increasing readback efficiency.

Process I/O to fieldbus interface circuit

Abstract: A field device such as a transmitter in a process control system includes conversion circuitry coupled between Fieldbus interface circuitry and transmitter interface circuitry. The transmitter includes a transducer for sensing a process variable and providing a transducer output. Measurement circuitry couples to the transducer output, processes the transducer output and provides a measurement output. The transmitter interface circuitry couples to the measurement circuitry and provides an interface output representative of the measurement output. Further, the transmitter interface circuitry receives a transmitter command and responds in accordance with the transmitter command. The Fieldbus interface circuitry is adapted to couple to a process control loop which operates in accordance with the Fieldbus standard.

Advanced designs of floating mass transducers

Abstract: A floating mass transducer for assisting hearing in a person is provided. Inertial vibration in the floating mass transducer (100) produces vibrations in the inner ear. In an exemplary embodiment, the floating mass transducer comprises a magnet assembly (12) and a coil (14) secured inside a housing (10) which is attached to bone within the middle ear. The coil is more rigidly secured to the housing than the magnet. The magnet assembly and coil are configured such that conducting alternating electrical current through the coil results in vibration of the magnet assembly and coil relative to one another. The vibration is caused by the interaction of the magnetic fields of the magnet assembly and coil. Because the coil is more rigidly secured to the housing than the magnet assembly, the vibrations of the coil cause the housing to vibrate. The floating mass transducer may generate vibrations in the inner ear by being attached to the skull or through a mouthpiece.

Ultrasonic endoscopic probe

Abstract: An ultrasonic endoscopic probe is provided with an articulating distal tip at which and ultrasonic transducer is located. The articulating section of the probe can be locked in an articulated position by a lock control located at a control section of the probe. The locking force is variably selectable by the user, so that the articulating section will be locked in position by a desired force. The articulating section is controlled by cables, which include cable tension adjustments that also serve to delimit the range of articulation. The articulating section is formed of alternating pivot rings with intervening polymeric pivot beads, which provide repetitively smooth articulation. The ultrasonic transducer is rotatable to steer the acoustic scan plane during use, and a sliding membrane between the transducer and its acoustic window allows the transducer to rotate smoothly without sticking.

Ultrasound catheter and method for imaging and hemodynamic monitoring

Abstract: A catheter apparatus for monitoring cardiovascular function is provided. The catheter apparatus contains an elongated body having proximal and distal ends; a phased-array ultrasonic transducer; and an electrical conductor. The phased-array ultrasonic transducer is mounted proximate the distal end of the catheter body to transmit ultrasound and receive resultant echoes so as to provide a field of view within which flow rates can be measured and features imaged. The electrical conductor is disposed in the catheter body for electrically connecting the transducer to control circuitry external of the catheter.

Ultrasound catheter probe

Abstract: An ultrasound catheter is disclosed for providing substantially real-time images of small cavities. The ultrasound catheter is characterized by separate and distinct materials for backing the transducers and for carrying the electronics components. The separate materials comprise an electronics carrier meeting the requirements for holding the integrated circuitry of the ultrasound device and a backing material displaying superior characteristics relating to reducing ringing and minimizing the effect of other sources of signal degradation in the transducer assembly. Also, in accordance with the present invention, a technique is described for connecting the conductor lines of the separate transducer assembly and electronics body.

Equipment and method for calibration and quality assurance of an ultrasonic bone analysis apparatus

Abstract: An improvement to calibration and quality assurance of an ultrasonic bone analysis apparatus is achieved by using phantoms. A received ultrasound signal that passed through a first phantom is used as a baseline for calculating BUA. The first phantom has an attenuation-versus-frequency profile that is substantially flat in a frequency range of 200 to 1000 kHz and a sound impedance that approximates that of soft human tissue. A propagation time of the signal is used to calibrate a zero point of the apparatus. A second phantom has an attenuation in a frequency range of 200-1000 kHz which approximates that of a human foot, including an attenuation-versus-frequency profile that is substantially linear in the frequency range of 200-600 kHz and is approximately 1 dB/MHz per mm. A received ultrasound signal that passed through the second phantom is used to calibrate the apparatus for a BUA calculation, and can also be used for at least one of determining and correcting a drift of the apparatus. A third phantom has a predetermined SOS that is substantially independent of temperature. A received ultrasound signal that passed through the third phantom is used to calibrate the apparatus for a SOS calculation, and can also be used for at least one of determining and correcting instrument drift. An ultrasonic signal is transmitted through mutually touching transducer pads. The received signal is used as a baseline for calculating BUA. A measurement of the propagation time of the received signal is compared with a temporally-proximate measurement of an ultrasonic signal that passed through a patient's heel to determine a time of propagation through the heel.

Scanning local‐acceleration microscopy

Abstract: By adapting a scanning force microscope to operate at frequencies above the highest tip–sample resonance, the sensitivity of the microscope to materials’ properties is greatly enhanced The cantilever’s behavior in response to high‐frequency excitation from a transducer underneath the sample is fundamentally different than to its low‐frequency response In this article, the motivations, instrumentation, theory, and first results for this technique are described

Conformal positioning assembly for microwave ablation catheter

Abstract: An ablation catheter includes an elongated flexible tubular member adapted to be inserted into a vessel in the body of a patient. A transmission line is disposed within the tubular member and a transducer is coupled to the transmission line for generating an electric field sufficiently strong to cause tissue ablation. A shape memory wire is positioned at a distal portion of the catheter adjacent the transducer to facilitate straightening the catheter tip after use. In one preferred embodiment, the shape memory wire may a flat wire which is formed from copper beryllium, a steel alloy, or nickel titanium. In another embodiment, the transmission line of the catheter is a coaxial cable, and the transducer is a helical antenna coil that is adapted to radiate electromagnetic energy in the microwave frequency range. In yet another embodiment, the shape memory wire is positioned within the antenna coil. Methods for manufacturing and using such ablation catheters are also described.