Showing papers on "Transducer published in 2003"
TL;DR: In this paper, the three key requirements of sensor design are determined by considering each of these three key factors: selection of a base oxide with high mobility of conduction electrons and satisfactory stability (transducer function), selection of foreign receptor which enhances surface reactions or adsorption of target gas (receptor function), and fabrication of a highly porous, thin sensing body (utility factor).
Abstract: Semiconductor gas sensors utilize porous polycrystalline resistors made of semiconducting oxides. The working principle involves the receptor function played by the surface of each oxide grain and the transducer function played by each grain boundary. In addition, the utility factor of the sensing body also takes part in determining the gas response. Therefore, the concepts of sensor design are determined by considering each of these three key factors. The requirements are selection of a base oxide with high mobility of conduction electrons and satisfactory stability (transducer function), selection of a foreign receptor which enhances surface reactions or adsorption of target gas (receptor function), and fabrication of a highly porous, thin sensing body (utility factor). Recent progress in sensor design based on these factors is described.
1,134 citations
TL;DR: The acoustic properties of the skull can be deduced from high resolution CT scans and used to achieve a noninvasive adaptive focusing, which could have promising applications in brain tumor hyperthermia but also in transcranial ultrasonic imaging.
Abstract: Developing minimally invasive brain surgery by high-intensity focused ultrasound beams is of great interest in cancer therapy. However, the skull induces strong aberrations both in phase and amplitude, resulting in a severe degradation of the beam shape. Thus, an efficient brain tumor therapy would require an adaptive focusing, taking into account the effects of the skull. In this paper, we will show that the acoustic properties of the skull can be deduced from high resolution CT scans and used to achieve a noninvasive adaptive focusing. Simulations have been performed with a full 3-D finite differences code, taking into account all the heterogeneities inside the skull. The set of signals to be emitted in order to focus through the skull can thus be computed. The complete adaptive focusing procedure based on prior CT scans has been experimentally validated. This could have promising applications in brain tumor hyperthermia but also in transcranial ultrasonic imaging.
475 citations
TL;DR: In this article, a power transmission system using directional ultrasound for power transmission includes a transmitting device and a receiving device, where the transmitting device has a set of ultrasound transducers forming an ultrasound transducer array.
Abstract: A power transmission system using directional ultrasound for power transmission includes a transmitting device and a receiving device. The transmitting device has a set of ultrasound transducers forming an ultrasound transducer array, wherein the array is a set of spaced individual transducers placed in the X-Y plane disposed to generate an ultrasound beam in the Z direction.
427 citations
TL;DR: In this article, the transducer array is disposed within a liquid-filled elastomeric material that more effectively couples ultrasound energy into the tumor, that is directly contacted with the device.
Abstract: An ultrasound system used for both imaging and delivery high intensity ultrasound energy therapy to treatment sites and a method for treating tumors and other undesired tissue within a patient's body with an ultrasound device. The ultrasound device has an ultrasound transducer array disposed on a distal end of an elongate, relatively thin shaft. In one form of the invention, the transducer array is disposed within a liquid-filled elastomeric material that more effectively couples ultrasound energy into the tumor, that is directly contacted with the device. Using the device in a continuous wave mode, a necrotic zone of tissue having a desired size and shape (e.g., a necrotic volume selected to interrupt a blood supply to a tumor) can be created by controlling at least one of the f-number, duration, intensity, and direction of the ultrasound energy administered. This method speeds the therapy and avoids continuously pausing to enable intervening normal tissue to cool.
333 citations
TL;DR: Both transducer focusing techniques proved successful in producing highly sensitive, high-frequency, single-element, ultrasonic-imaging transducers that could possibly allow for an increase in depth of penetration, higher image signal-to-noise ratio (SNR), and improved image contrast at high frequencies when compared to previously reported results.
Abstract: This paper discusses the design, fabrication, and testing of sensitive broadband lithium niobate (LiNbO/sub 3/) single-element ultrasonic transducers in the 20-80 MHz frequency range. Transducers of varying dimensions were built for an f# range of 2.0-3.1. The desired focal depths were achieved by either casting an acoustic lens on the transducer face or press-focusing the piezoelectric into a spherical curvature. For designs that required electrical impedance matching, a low impedance transmission line coaxial cable was used. All transducers were tested in a pulse-echo arrangement, whereby the center frequency, bandwidth, insertion loss, and focal depth were measured. Several transducers were fabricated with center frequencies in the 20-80 MHz range with the measured -6 dB bandwidths and two-way insertion loss values ranging from 57 to 74% and 9.6 to 21.3 dB, respectively. Both transducer focusing techniques proved successful in producing highly sensitive, high-frequency, single-element, ultrasonic-imaging transducers. In vivo and in vitro ultrasonic backscatter microscope (UBM) images of human eyes were obtained with the 50 MHz transducers. The high sensitivity of these devices could possibly allow for an increase in depth of penetration, higher image signal-to-noise ratio (SNR), and improved image contrast at high frequencies when compared to previously reported results.
321 citations
TL;DR: In this paper, a new method for fabricating capacitive micromachined ultrasonic transducers (CMUTs) that uses a wafer bonding technique is introduced. But the method is not suitable for large CMUTs.
Abstract: Introduces a new method for fabricating capacitive micromachined ultrasonic transducers (CMUTs) that uses a wafer bonding technique. The transducer membrane and cavity are defined on an SOI (silicon-on-insulator) wafer and on a prime wafer, respectively. Then, using silicon direct bonding in a vacuum environment, the two wafers are bonded together to form a transducer. This new technique, capable of fabricating large CMUTs, offers advantages over the traditionally micromachined CMUTs. First, forming a vacuum-sealed cavity is relatively easy since the wafer bonding is performed in a vacuum chamber. Second, this process enables better control over the gap height, making it possible to fabricate very small gaps (less than 0.1 /spl mu/m). Third, since the membrane is made of single crystal silicon, it is possible to predict and control the mechanical properties of the membrane to within 5%. Finally, the number of process steps involved in making a CMUT has been reduced from 22 to 15, shortening the device turn-around time. All of these advantages provide repeatable fabrication of CMUTs featuring predictable center frequency, bandwidth, and collapse voltage.
312 citations
TL;DR: In this paper, the authors present an overview of the literature on piezoelectric shunt damping and discuss recent observations on the feedback nature of shunt-based damping systems.
Abstract: Research on shunted piezoelectric transducers, performed mainly over the past decade, has generated new opportunities for control of vibration and damping in flexible structures. This is made possible by the strong electromechanical coupling associated with modern piezoelectric transducers. In vibration control applications, a piezoelectric transducer is bonded to, or embedded in a base structure. As the structure deforms, the piezoelectric element strains and converts a portion of the structural vibration energy into electrical energy. By shunting the piezoelectric transducer to an electrical impedance, a part of the induced electrical energy can be dissipated. Hence, the impedance acts as a means of extracting mechanical energy from the base structure. This paper reviews recent research related to the use of shunted piezoelectric elements for vibration damping and control. In particular, the paper presents an overview of the literature on piezoelectric shunt damping and discusses recent observations on the feedback nature of piezoelectric shunt damping systems.
300 citations
01 Jan 2003
TL;DR: An overview of the literature on piezoelectric shunt damping is presented and recent observations on the feedback nature of piez ZoelectricShunt dampers are discussed, as a means of extracting mechanical energy from the base structure.
Abstract: Research on shunted piezoelectric transducers, per- formed mainly over the past decade, has generated new opportuni- ties for control of vibration and damping in flexible structures. This is made possible by the strong electromechanical coupling associ- ated with modern piezoelectric transducers. In vibration control applications, a piezoelectric transducer is bonded to, or embedded in a base structure. As the structure deforms, the piezoelectric el- ement strains and converts a portion of the structural vibration energy into electrical energy. By shunting the piezoelectric trans- ducer to an electrical impedance, a part of the induced electrical energy can be dissipated. Hence, the impedance acts as a means of extracting mechanical energy from the base structure. This paper reviews recent research related to the use of shunted piezoelec- tric elements for vibration damping and control. In particular, the paper presents an overview of the literature on piezoelectric shunt damping and discusses recent observations on the feedback nature of piezoelectric shunt damping systems.
299 citations
Patent•
14 Apr 2003
TL;DR: In this article, the authors describe a telemetry system consisting of a first or control implant including a first acoustic transducer, and a second implant with a switch and an acoustic transducers coupled to the switch.
Abstract: Systems and methods provide intrabody communication using acoustic telemetry. The system includes a first or control implant including a first acoustic transducer, and a second implant including a switch and a second acoustic transducer coupled to the switch. The second acoustic transducer receives acoustic signals from the first acoustic transducer for closing the switch to activate the second implant. The second implant may include a sensor for measuring a physiological parameter that is transmitted using acoustic signals including the physiological data to the first implant. For example, the second implant may measure pressure in the patient's heart that may be used by the first implant to control a pacemaker. Alternatively, the second implant may blood sugar concentration that may be used by the first implant to control an insulin pump. Alternatively, the first implant may store and transfer the data to an external device for monitoring the patient.
280 citations
05 Oct 2003
TL;DR: A 2D array for acquiring 3D images is described and Interconnection methods are presented that connect elements of the array to integrated circuits (ICs) within the transducer.
Abstract: A 2D array for acquiring 3D images is described. Interconnection methods are presented that connect elements of the array to integrated circuits (ICs) within the transducer. These ICs simultaneously process signals from ALL elements forming a fully sampled array. Comparisons are made with mechanical and sparse array solutions. Several signal processing options for use within the ICs are presented.
234 citations
TL;DR: The finite element method (FEM) is used for the calculation and measurement of coupling coefficient for capacitive micromachined ultrasonic transducers (CMUTs) and indicates that the electromechanical coupling coefficient is independent of any series capacitance that may exist in the structure.
Abstract: The electromechanical coupling coefficient is an important figure of merit of ultrasonic transducers. The transducer bandwidth is determined by the electromechanical coupling efficiency. The coupling coefficient is, by definition, the ratio of delivered mechanical energy to the stored total energy in the transducer. In this paper, we present the calculation and measurement of coupling coefficient for capacitive micromachined ultrasonic transducers (CMUTs). The finite element method (FEM) is used for our calculations, and the FEM results are compared with the analytical results obtained with parallel plate approximation. The effect of series and parallel capacitances in the CMUT also is investigated. The FEM calculations of the CMUT indicate that the electromechanical coupling coefficient is independent of any series capacitance that may exist in the structure. The series capacitance, however, alters the collapse voltage of the membrane. The parallel parasitic capacitance that may exist in a CMUT or is external to the transducer reduces the coupling coefficient at a given bias voltage. At the collapse, regardless of the parasitics, the coupling coefficient reaches unity. Our experimental measurements confirm a coupling coefficient of 0.85 before collapse, and measurements are in agreement with theory.
TL;DR: Increase of mass-sensitivity with coil diameter reduction is demonstrated experimentally for planar microcoils and the achieved sensitivity enables acquisition of an 1H spectrum of 160 microg sucrose in D2O, corresponding to a proof-of-concept for on-chip NMR spectroscopy.
TL;DR: Several lesions are induced in fresh liver and brain samples through human skulls, demonstrating the accuracy and the steering capabilities of the system.
Abstract: A sparse phased array is specially designed for non-invasive ultrasound transskull brain therapy. The array is made of 200 single elements corresponding to a new generation of high power transducers developed in collaboration with Imasonic (Besancon, France). Each element has a surface of 0.5 cm2 and works at 0.9 MHz central frequency with a maximum 20 W cm(-2) intensity on the transducer surface. In order to optimize the steering capabilities of the array, several transducer distributions on a spherical surface are simulated: hexagonal, annular and quasi-random distributions. Using a quasi-random distribution significantly reduces the grating lobes. Furthermore, the simulations show the capability of the quasi-random array to electronically move the focal spot in the vicinity of the geometrical focus (up to +/- 15 mm). Based on the simulation study, the array is constructed and tested. The skull aberrations are corrected by using a time reversal mirror with amplitude correction achieved thanks to an implantable hydrophone, and a sharp focus is obtained through a human skull. Several lesions are induced in fresh liver and brain samples through human skulls, demonstrating the accuracy and the steering capabilities of the system.
TL;DR: This work reports on methodology for employing a conventional linear transducer array as a thermoacoustic detector in a therMoacoustic computed tomography (TCT) device, which has been designed for imaging small animals, e.g., athymic nude mice.
Abstract: We report on methodology for employing a conventional linear transducer array as a thermoacoustic detector in a thermoacoustic computed tomography (TCT) device, which has been designed for imaging small animals, e.g., athymic nude mice. We tested this concept using a 5 MHz, 128-element linear array (Acuson model L538). Thermoacoustic emissions were induced in a tissue-mimicking phantom using a Nd:YAg laser, operated at 1064 nm. Two-dimensional, axial "slice" images were formed using a filtered-backprojection algorithm. In-plane spatial resolution was measured as better than 200 microns with a slice thickness of 1.5 mm (full width at half maximum). The same detector, when operated as a conventional phased array, produced conventional ultrasound images in perfect registration with the TCT images.
TL;DR: In this paper, a method for ablating tissue with ultrasonic energy is presented, which is based on the shape of one or more ultrasonic transducers to focus ultrasonic energies in a radial direction.
Abstract: A method for ablating tissue with ultrasonic energy is provided. The method including: generating ultrasonic energy from one or more ultrasonic transducers; and focusing the ultrasonic energy in the radial direction by one of: shaping the one or more ultrasonic transducers to focus ultrasonic energy in the radial direction; and arranging one or more lenses proximate the one or more ultrasonic transducers for focusing the ultrasonic energy from the one or more ultrasonic transducers in a radial direction.
Patent•
31 Dec 2003
TL;DR: In this paper, the transducer induces bending waves in the touch panel and generates a bending wave signal responsive to the sensed bending waves, which is then compared with the untouched condition signal.
Abstract: A touch sensing device includes a plurality of sensors and an emitting transducer coupled to a touch panel. The transducer induces bending waves in the touch panel. The sensors sense bending waves in the touch panel and generate a bending wave signal responsive to the sensed bending waves. A controller identifies an untouched condition signal responsive to the induced bending waves. The controller compares the untouched condition signal to the bending wave signal, and detects a touch on the touch panel based on the comparison.
Patent•
01 Oct 2003
TL;DR: In this paper, the authors used a high compliance material, resonating the ultrasound sensing transducer, using an attenuation-reducing coating and/or thickness, and using optical wavelength discrimination.
Abstract: An imaging guidewire can include one or more optical fibers communicating light along the guidewire. At or near its distal end, one or more blazed or other fiber Bragg gratings (FBGs) directs light to a photoacoustic transducer material that provides ultrasonic imaging energy. Returned ultrasound is sensed by an FBG sensor. A responsive signal is optically communicated to the proximal end of the guidewire, and processed to develop a 2D or 3D image. In one example, the guidewire outer diameter is small enough such that an intravascular catheter can be passed over the guidewire. Techniques for improving ultrasound reception include using a high compliance material, resonating the ultrasound sensing transducer, using an attenuation-reducing coating and/or thickness, and/or using optical wavelength discrimination. Techniques for improving the ultrasound generating transducer include using a blazed FBG, designing the photoacoustic material thickness to enhance optical absorption. Techniques for distinguishing plaque or vulnerable plaque may be used to enhance the displayed image.
Patent•
14 Apr 2003
TL;DR: In this article, the relative position of an adjacent movable reflector assembly can be measured in six degrees of freedom by variations in detected light amplitude, which may be facilitated by the compact design of the transducer means.
Abstract: The invention relates to improved multi-axis joysticks and associated multi-axis optical displacement measurement means. The displacement measuring means may include one or more light emitters and one or more light detectors, preferably mounted in a planar hexagonal array. The relative position of an adjacent movable reflector assembly can be measured in six degrees of freedom by variations in detected light amplitude. Various ergonomic configurations of six axis joystick embodiments which may be facilitated by the compact design of the transducer means are disclosed. Means for dynamically adjusting coordinate transformations for construction machinery control are also disclosed.
TL;DR: The advantages of utilizing a new technique that performs radiofrequency (RF) signal tracking to estimate the localized oscillatory motion resulting from the harmonic radiation force produced by two focused ultrasound (US) transducer elements with overlapping beams oscillating at distinct frequencies are discussed.
Abstract: Several techniques have been developed in an effort to estimate mechanical properties of tissues. These techniques typically estimate static or harmonic motion resulting from an externally or internally applied mechanical stimulus. In this paper, we discuss the advantages of utilizing a new technique that performs radiofrequency (RF) signal tracking to estimate the localized oscillatory motion resulting from the harmonic radiation force produced by two focused ultrasound (US) transducer elements with overlapping beams oscillating at distinct frequencies. Finite-element and Monte-Carlo simulations were performed to characterize the range of oscillatory displacements produced by a harmonic radiation force. In the experimental verification, three transducers were used: two single-element focused transducers and one lead zirconate-titanate (PZT) composite 16-element probe. Four agar gels were utilized to determine the effect of stiffness on the motion amplitude. Estimates of the displacement relative to the initial position (i.e., at the onset of the application of the radiation force) were obtained during the application of the radiation force that oscillated at frequencies ranging between 200 Hz and 800 Hz. In the simulations, the estimated oscillatory displacement spanned from −800 to 600 μm and the frequencies of excitation could easily be estimated from the temporal variation of the displacement. In addition, a frequency upshift (on the order of tens of Hz) was estimated with stiffness increase. Furthermore, an exponential decrease of the displacement amplitude with stiffness was observed at all frequencies investigated. An M-mode version to depict both the spatial and temporal variations of the locally induced displacement was used. In experiments with gels of different stiffness, the resulting amplitude of the harmonic displacement estimated oscillated at the same frequencies and ranged from −300 to 250 μm. An exponential decrease of the displacement amplitude with the gel stiffness was also observed. In tissue experiments, the results showed that the method is feasible in tissues and that focused US surgery (FUS) ablation can be detected. These preliminary results demonstrate the feasibility of imaging localized harmonic motion as induced by an oscillatory US radiation force. Due to the highly localized and harmonic nature of the estimated response, this technique may be proven to be highly suitable for simple and accurate estimation of the elastic modulus variation in tissues due to disease. (E-mail: elisak@bwh.harvard.edu)
Patent•
TL;DR: In this article, a method and device for wound treatment with a combination of laser and ultrasound waves comprises a probe to produce a laser beam and transducer to produce ultrasonic waves.
Abstract: The method and device of the present invention for wound treatment with a combination of laser and ultrasound waves comprises a probe to produce a laser beam and transducer to produce ultrasonic waves. The ultrasonic transducer has tip with a distal end comprising a radiation surface. A liquid is directed to the radiation surface wherein an directed atomized particle spray of the liquid is created upon contact of the liquid with the radiation surface. The laser beam and spray directed to the wound from at least 0,1 inches transmits ultrasound waves as well as particles and has an radiation, irrigation, mechanical cleansing, liquid energizing and bactericide effect on the wound.
TL;DR: In this paper, a hand held ultrasonic instrument is provided in a portable unit which performs both B mode and Doppler imaging, including a transducer array mounted in a hand-held enclosure, with an integrated circuit transceiver connected to the elements of the array for the reception of echo signals.
Abstract: A hand held ultrasonic instrument is provided in a portable unit which performs both B mode and Doppler imaging. The instrument includes a transducer array mounted in a hand-held enclosure, with an integrated circuit transceiver connected to the elements of the array for the reception of echo signals. A digital signal processing circuit performs both B mode and Doppler signal processing such as filtering, detection and Doppler estimation, as well as advanced functions such as assembly of multiple zone focused scanlines, synthetic aperture formation, depth dependent filtering, speckle reduction, flash suppression, and frame averaging.
TL;DR: The feasibility of transmitting electric energy through a metal wall by propagating acoustic waves using piezoelectric transducers is examined by studying the efficiency of power transmission and its dependence upon the relevant system parameters for a simplified system consisting of an elastic plate sandwiched by two piez Zoelectric layers.
Abstract: The feasibility of transmitting electric energy through a metal wall by propagating acoustic waves using piezoelectric transducers is examined by studying the efficiency of power transmission and its dependence upon the relevant system parameters for a simplified system consisting of an elastic plate sandwiched by two piezoelectric layers. One of these layers models the driving transducer for generating acoustic wave, and the other layer models the receiving transducer for converting the acoustic energy into electric energy to power a load circuit. The output voltage, the output power, and the efficiency of this system are expressed as explicit functions of the system parameters. A numerical example is included to illustrate the dependence of the system performance upon the physical and geometrical parameters.
TL;DR: In this paper, a free energy model for magnetostrictive transducers operating in hysteretic and nonlinear regimes is presented. Butts et al. presented a model for a typical Terfenol-D transducer with constant internal fields and the effects of material nonhomogeneities and nonconstant effective fields.
Abstract: This article addresses the development of a free energy model for magnetostrictive transducers operating in hysteretic and nonlinear regimes. Such models are required both for material and system characterization and for model-based control design. The model is constructed in two steps. In the first, Helmholtz and Gibbs free energy relations are constructed for homogeneous materials with constant internal fields. In the second step, the effects of material nonhomogeneities and nonconstant effective fields are incorporated through the construction of appropriate stochastic distributions. Properties of the model are illustrated through comparison and prediction of data collected from a typical Terfenol-D transducer.
TL;DR: In this paper, a flexible wireless MEMS microphone includes a substrate of a flexible polymeric material, a flexible MEMS transducer structure formed on the substrate by PECVD, an antenna printed on a substrate for communicating with an outside source, a wire and interface circuit embedded in the substrate to electrically connect the flexible transducers and the antenna, and a flexible battery layer electrically connected to the substrate for supplying power.
Abstract: A flexible wireless MEMS microphone includes a substrate of a flexible polymeric material, a flexible MEMS transducer structure formed on the substrate by PECVD, an antenna printed on the substrate for communicating with an outside source, a wire and interface circuit embedded in the substrate to electrically connect the flexible MEMS transducer and the antenna, a flexible battery layer electrically connected to the substrate for supplying power to the MEMS transducer, and a flexible bluetooth module layer electrically connected to the battery layer. The flexible MEMS transducer includes a flexible substrate, a membrane layer deposited on the substrate, a lower electrode layer formed on the membrane layer, an active layer formed by depositing a piezopolymer on the lower electrode layer, an upper electrode layer formed on the active layer, and a first and a second connecting pad electrically connected to the lower and upper electrode layers, respectively.
Patent•
13 May 2003
TL;DR: In this paper, an ultrasonic surgical system is presented that is economical to produce and utilize, by including at least one disposable component, which can be adapted to be press-fit onto each other.
Abstract: An ultrasonic surgical system is presented that is economical to produce and utilize, by including at least one disposable component. The ultrasonic surgical system includes an ultrasonic transducer for converting electric signals into ultrasonic vibrations. An ultrasonic transmission coupler is connected to the transducer, so as to receive the ultrasonic vibrations from the transducer. An ultrasonic vibration element is coupled to the distal end of the ultrasonic transmission coupler. At least one of the ultrasonic transducer, the ultrasonic transmission coupler, and the ultrasonic vibration element is disposable. The components of the ultrasonic surgical system are not precision-cut, and are adapted to be press-fit onto each other. The ultrasonic surgical system may be tuned to a desired resonant frequency by varying the lengths of the disposable components.
TL;DR: In this article, a system for focusing ultrasonic energy through intervening tissue into a target site within a tissue region includes a transducer array, an imager for imaging the tissue region, a processor receiving images from the imager to determine boundaries between different tissue types within the intervening tissue and generate correction factors for the transducers to compensate for refraction occurring at the boundaries between the tissue types and for variations in speed of sound.
Abstract: A system for focusing ultrasonic energy through intervening tissue into a target site within a tissue region includes a transducer array including transducer element, an imager for imaging the tissue region, a processor receiving images from the imager to determine boundaries between different tissue types within the intervening tissue and generate correction factors for the transducer elements to compensate for refraction occurring at the boundaries between the tissue types and/or for variations in speed of sound. A controller is coupled to the processor and the transducer array to receive the correction factors and provide excitation signals to the transducer elements based upon the correction factors. The correction factors may include phase and/or amplitude correction factors, and the phases and/or amplitudes of excitation signals provided to the transducer elements may be adjusted based upon the phase correction factors to focus the ultrasonic energy to treat tissue at the target site.
TL;DR: In this paper, an acoustic-to-electrical transducer for sensing body sounds is described, which comprises a capacitive sensor, whereby a stethoscope diaphragm forms one plate of a capacitor, with the second plate of the capacitor being co-planar to the diaphrasm.
Abstract: An acoustic-to-electrical transducer for sensing body sounds is disclosed. The transducer comprises a capacitive sensor, whereby a stethoscope diaphragm forms one plate of a capacitor, with the second plate of the capacitor being co-planar to the diaphragm. The capacitance of the two plates varies with the distance between them, said distance being modified by motion of the diaphragm in response to sound pressure. The sensor, circuitry, manufacturing methods and improvements are disclosed.
Patent•
31 Oct 2003
TL;DR: In this paper, a disk drive is disclosed which generates a pole tip protrusion (PTP) measurement by performing a write operation to heat the transducer while measuring a fly height of the transducers.
Abstract: A disk drive is disclosed which generates a pole tip protrusion (PTP) measurement by performing a write operation to heat the transducer while measuring a fly height of the transducer. A first data sequence written to the disk is read without heating the transducer to generate a first signal measurement. A second data sequence is then written to the disk in order to heat the transducer, and the first data sequence is again read to generate a second signal measurement. The PTP measurement is then generated in response to the first and second signal measurements.
TL;DR: A new phenomenon in ultrasonic cavitation field is reported, where cavitation bubbles are observed to self-arrange in a cone-like macrostructure in the vicinity of transducer radiating surface.
Patent•
31 Jul 2003
TL;DR: An integrated current sensor includes a magnetic field transducer such as a Hall effect sensor, a magnetic core, and an electrical conductor as discussed by the authors, where the core and the elements are dimensioned such that little or no relative movement among the elements is possible.
Abstract: An integrated current sensor includes a magnetic field transducer such as a Hall effect sensor, a magnetic core, and an electrical conductor The conductor includes features for receiving portions of the Hall effect sensor and the core and the elements are dimensioned such that little or no relative movement among the elements is possible