Showing papers on "Transducer published in 2006"

Ultrasonic transducer control method and system

Abstract: The present invention relates to methods for velocity control of transducers that can compensate both for age related changes as well as the more immediate changes that occur during operation. In one aspect of the invention, the non-motional reactive current is measured at two predetermined frequencies, one below (Ilf) and one above the resonance frequency (Ihf). A correction factor is calculated from these measured currents is used to maintain a specified value of end effector velocity or displacement. In another aspect of the invention, methods are provided for the detection of secondary resonances that could be indicative of end effector fault conditions. In another aspect of the invention, velocity control is achieved.

Hybrid magnetic-based and impedance-based position sensing

Abstract: A position sensing system includes a probe adapted to be introduced into a body cavity of a subject. The probe includes a magnetic field transducer and at least one probe electrodes. A control unit is configured to measure position coordinates of the probe using the magnetic field transducer. The control unit also measures an impedance between the at least one probe electrodes and one or more points on a body surface of the subject. Using the measured position coordinates, the control unit calibrates the measured impedance.

Broadband ultrasonic location systems for improved indoor positioning

Abstract: Ultrasonic location systems are a popular solution for the provision of fine-grained indoor positioning data. Applications include enhanced routing for wireless networks, computer-aided navigation, and location-sensitive device behavior. However, current ultrasonic location systems suffer from limitations due to their use of narrowband transducers, This paper investigates the use of broadband ultrasound for indoor positioning systems. Broadband ultrasonic transmitter and receiver units have been developed and characterized. The utilization of these units to construct two positioning systems with different architectures serves to highlight and affirm the concrete, practical benefits of broadband ultrasound for locating people and devices indoors.

Piezoelectric and semiconducting coupled power generating process of a single ZnO belt/wire. A technology for harvesting electricity from the environment.

Abstract: This paper presents the experimental observation of piezoelectric generation from a single ZnO wire/belt for illustrating a fundamental process of converting mechanical energy into electricity at nanoscale. By deflecting a wire/belt using a conductive atomic force microscope tip in contact mode, the energy is first created by the deflection force and stored by piezoelectric potential, and later converts into piezoelectric energy. The mechanism of the generator is a result of coupled semiconducting and piezoelectric properties of ZnO. A piezoelectric effect is required to create electric potential of ionic charges from elastic deformation; semiconducting property is necessary to separate and maintain the charges and then release the potential via the rectifying behavior of the Schottky barrier at the metal-ZnO interface, which serves as a switch in the entire process. The good conductivity of ZnO is rather unique because it makes the current flow possible. This paper demonstrates a principle for harvesting energy from the environment. The technology has the potential of converting mechanical movement energy (such as body movement, muscle stretching, blood pressure), vibration energy (such as acoustic/ultrasonic wave), and hydraulic energy (such as flow of body fluid, blood flow, contraction of blood vessels) into electric energy that may be sufficient for self-powering nanodevices and nanosystems in applications such as in situ, real-time, and implantable biosensing, biomedical monitoring, and biodetection.

Mechatronics: Dynamics of Electromechanical and Piezoelectric Systems

Abstract: Lagrangian dynamics of mechanical systems 1.1 Introduction 1.2 Kinetic state functions 1.3 Generalized coordinates, kinematic constraints 1.4 The principle of virtual work 1.5 D'Alembert's principle 1.6 Hamilton's principle 1.7 Lagrange's equations 1.8 Lagrange's equations with constraints 1.9 Conservation laws 1.10 More on continuous systems 1.11 References 2 Dynamics of electrical networks 2.1 Introduction 2.2 Constitutive equations for circuit elements 2.3 Kirchhoff's laws 2.4 Hamilton's principle for electrical networks 2.5 Lagrange's equations 2.6 References 3 Electromechanical Systems 3.1 Introduction 3.2 Constitutive relations for transducers 3.3 Hamilton's Principle 3.4 Lagrange's equations 3.5 Examples 3.6 General electromechanical transducer 3.7 References 4 Piezoelectric Systems 4.1 Introduction 4.2 Piezoelectric transducer 4.3 Constitutive relations of a discrete transducer 4.4 Structure with a discrete piezoelectric transducer 4.5 Multiple transducer systems 4.6 General piezoelectric structure 4.7 Piezoelectric material 4.8 Hamilton's principle 4.9 Rosen's piezoelectric transformer 4. 10 References 5 Piezoelectric laminates 5.1 Piezoelectric beam actuator 5.2 Laminar sensor 5.3 Spatial modal filters 5.4 Active beam with collocated actuator-sensor 5.5 Piezoelectric laminates 5.6 References 6 Active and Passive Damping with Piezoelectric Transducers 6.1 Introduction 6.2 Active strut, open-loop FRF 6.3 Active damping via 1FF 6.4 Admittance of the piezoelectric transducer 6.5 Damping via resistive shunting 6.6 Inductive shunting 6.7 Decentralized control 6.8 General piezoelectric structure 6.9 Self-sensing 6.10 Other active damping strategies 6.11 Remark 6.12 References Bibliography Index

A variable-capacitance vibration-to-electric energy harvester

Abstract: Past research on vibration energy harvesting has focused primarily on the use of magnets or piezoelectric materials as the basis of energy transduction, with few experimental studies implementing variable-capacitance-based scavenging. In contrast, this paper presents the design and demonstration of a variable-capacitance vibration energy harvester that combines an asynchronous diode-based charge pump with an inductive energy flyback circuit to deliver 1.8 /spl mu/W to a resistive load. A cantilever beam variable capacitor with a 650-pF dc capacitance and a 348-pF zero-to-peak ac capacitance, formed by a 43.56cm/sup 2/ spring steel top plate attached to an aluminum base, drives the charge pump at its out-of-plane resonant frequency of 1.56 kHz. The entire harvester requires only one gated MOSFET for energy flyback control, greatly simplifying the clocking scheme and avoiding synchronization issues. Furthermore, the system exhibits a startup voltage requirement below 89 mV, indicating that it can potentially be turned on using just a piezoelectric film.

High-strain ionomeric–ionic liquid electroactive actuators

Abstract: Ionomeric polymers are a class of electromechanical transducer consisting of an ionomeric substrate with metal-plated electrodes. Application of a low-voltage ( 10 Hz), but this effect is small compared to the increase in strain produced by maximizing the capacitance. Increasing capacitance produces a transducer that is able to achieve >2% strain (ɛ) at voltage levels of ±3 V.

Medical ultrasound system and handpiece and methods for making and tuning

Abstract: Several embodiments of medical ultrasound handpieces are described each including a medical ultrasound transducer assembly. An embodiment of a medical ultrasound system is described, wherein the medical ultrasound system includes a medical ultrasound handpiece having a medical ultrasound transducer assembly and includes an ultrasonically-vibratable medical-treatment instrument which is attachable to a distal end of the transducer assembly. An embodiment of a medical ultrasound system is described, wherein the medical ultrasound system has a handpiece including a medical ultrasound transducer assembly and including a housing or housing component surrounding the transducer assembly. A method for tuning a medical ultrasound handpiece includes machining at least a distal non-threaded portion of an instrument-attachment stud of the transducer assembly to match a measured fundamental frequency to a desired fundamental frequency to within a predetermined limit. A method for making a medical ultrasound transducer assembly determines acceptable gains for gain stages of the transducer assembly.

Miniature Silicon Condenser Microphone

Abstract: A silicon condenser microphone package includes a transducer unit, a substrate, and a cover. The substrate includes an upper surface transducer unit is attached to the upper surface of the substrate and overlaps at least a portion of the recess wherein a back volume of the transducer unit is formed between the transducer unit and the substrate. The cover is placed over the transducer unit and either the cover or the substrate includes an aperture.

Tactile sensor arrays using fiber Bragg grating sensors

Abstract: This paper describes two kinds of 3 × 3 force sensor arrays using fiber Bragg gratings (FBG) and transducers for tactile sensation to detect a distributed normal force. One array is developed for a large area tactile sensor that has good sensitivity but low spatial resolution, similar to human body skin. The other is for a small area tactile sensor that has good sensitivity and spatial resolution, similar to human finger skin. The transducer is designed such that it is not affected by chirping and light loss. We also present the fabrication process and experimental verification of the prototype sensors. Experimental tests show that the newly designed sensors have good performance: good sensitivity, repeatability, and no-hysteresis. The load calibration is accomplished by a verified uniaxial load cell. In order to provide a more precise measurement, temperature compensation is applied to all taxels. These force sensor arrays are flexible enough to be attached to a curved surface and they also have simple wiring compared with other types of small force sensors for tactile sensation.

A turnstile junction waveguide orthomode transducer

Abstract: An orthomode transducer with a circular waveguide input and two rectangular waveguide outputs is described. The design utilizes a turnstile junction and two E-plane power combiners. A K-band version of this device has been constructed and tested. From 18 to 26 GHz, the input reflection coefficient was less than -19 dB, the cross-polarization was less than -48 dB, and the transmission loss was ~0.15 dB. We estimate the mechanical tolerances that would be required to scale this device to the 200-270-GHz band for use in a dual-polarization radio-astronomy receiver

Distributed underwater electromagnetic communication system

Abstract: An extended underwater electromagnetic transducer is provided with an electrically insulated transmission line typically connected to a transmitter or receiver or transceiver system. The transmission line allows near-field communications with another transmitter or receiver or transceiver system. The transmission line provided is relatively long, the through water signal path length can be significantly reduced.

Annular-ring CMUT arrays for forward-looking IVUS: transducer characterization and imaging

Abstract: In this study, a 64-element, 1.15-mm diameter annular-ring capacitive micromachined ultrasonic transducer (CMUT) array was characterized and used for forward-looking intravascular ultrasound (IVUS) imaging tests. The array was manufactured using low-temperature processes suitable for CMOS electronics integration on a single chip. The measured radiation pattern of a 43 /spl times/ 140-/spl mu/m array element depicts a 40/spl deg/ view angle for forward-looking imaging around a 15-MHz center frequency in agreement with theoretical models. Pulse-echo measurements show a -10-dB fractional bandwidth of 104% around 17 MHz for wire targets 2.5 mm away from the array in vegetable oil. For imaging and SNR measurements, RF A-scan data sets from various targets were collected using an interconnect scheme forming a 32-element array configuration. An experimental point spread function was obtained and compared with simulated and theoretical array responses, showing good agreement. Therefore, this study demonstrates that annular-ring CMUT arrays fabricated with CMOS-compatible processes are capable of forward-looking IVUS imaging, and the developed modeling tools can be used to design improved IVUS imaging arrays.

Method of monitoring operation of a disk drive by analyzing the envelope of a read-back signal in the frequency domain

Abstract: A method monitors operation of a disk drive. The method includes providing a disk drive which includes a rotating disk and a head having a read transducer in proximity to a surface of the disk and an adjustment mechanism which controllably adjusts an average relative spacing between the read transducer and the surface. The method further includes generating a read-back signal by reading from the surface using the read transducer. The read-back signal includes a high frequency carrier signal having an envelope that is modulated by a lower frequency signal. The method further includes varying the average relative spacing between the read transducer and the surface using the adjustment mechanism. The method further includes analyzing the envelope in the frequency domain and detecting an emergence of at least one frequency component of the envelope within an air bearing resonance range of frequencies.

On the development and testing of a guided ultrasonic wave array for structural integrity monitoring

Abstract: The prototype of a guided ultrasonic wave array for the structural integrity monitoring of large, plate-like structures has been designed, built, and tested. The development of suitably small transducers for the excitation and measurement of the first antisymmetric Lamb wave mode A/sub 0/ is described. The array design consists of a ring of 32 transducers, permanently bonded to the structure with a protective membrane, in a compact housing with the necessary multiplexing electronics. Using a phased addition algorithm with dispersion compensation and deconvolution in the wavenumber domain, a good dynamic range can be achieved with a limited number of transducers. Limitations in the transducer design and manufacture restricted the overall dynamic range achieved to 27 dB. Laboratory measurements for a steel plate containing various defects have been performed. The results for standard defects are compared to theoretical predictions and the sensitivity of the array device for defect detection has been established. Simulated corrosion pitting and a defect cut with an angle grinder simulating general corrosion were detected.

High sensitivity rfid tag integrated circuits

Abstract: A method and apparatus for an ultra-high sensitivity, low cost, passive (no battery) low-power energy harvesting data transmitting circuit energy, such as a RFID (Radio Frequency IDentification) tag integrated circuit 'chip.' By using combinations of special purpose design enhancements, the low-power energy harvesting passive data transmitting circuit, such as the RFID tag chip, operates in the sub-microwatt power range. The chip power should be derived from a low-microwatt per square centimeter RF field radiated to the RFID tag antenna from the tag reader (interrogator) or derived from a suitable low signal source, such as a sonic transducer (e.g., a piezoelectric transducer or a low level DC source, such as a bi-metallic or chemical source).

Head having a transducer heater and an air bearing surface with a flow-diversion dam and pressure-relief trough disposed upstream of the transducer

Abstract: A head for use in an information storage device includes a novel ABS, and a transducer with a heating element. The ABS includes a transducer pad that includes a surface in a first plane. The ABS also includes a pressure-relief trough that is recessed from the first plane by at least 0.1 microns and has an upstream breadth of no more than one fourth of the total length of the slider. The pressure-relief trough is disposed immediately upstream of the transducer pad and continuously spans the total width of the transducer pad. The ABS also includes a flow-diversion dam that has a dam surface that lies in the first plane. The dam surface continuously spans the total width of the transducer pad. The dam surface is disposed immediately upstream of the pressure-relief trough and generally downstream of a sub-ambient pressure cavity.

Micro-Electro-Mechanical Transducers

Abstract: A micro-electro-mechanical transducer (such as a cMUT) that has a movable mechanical part to transform energy. The transducer (511) has a substrate (501), a top plate (540), and a resilient structure (520) therebetween. The resilient structure has multiple connectors (530) distributed over the device element area to vertically transport the top player with distributed support not limited to edges. The resilient structure (520) may be cantilevers, or cantilever-containing structures such as bridges or crossbars, formed using a middle spring layer coveting cavities on the substrate. Connectors (530) define a transducing space below the top plate (540). The resilient structure (520) such as cantilevers enable a vertical displacement of the connectors, which transports the top plate (540) in a piston-like motion to change the transducing space and to effectuate energy transformation. No separate cells are necessary for each addressable transducer element. Multiple device elements can be made on the same substrate.

High frequency array ultrasound system

Abstract: A system for acquiring an ultrasound signal comprises a signal processing unit adapted for acquiring a received ultrasound signal from an ultrasound transducer having a plurality of elements. The system is adapted to receive ultrasound signals having a frequency of at least 20 megahertz (MHz) with a transducer having a field of view of at least 5.0 millimeters (mm) at a frame rate of at least 20 frames per second (fps). The signal processing can further produce an ultrasound image from the acquired ultrasound signal. The transducer can be a linear array transducer, a phased array transducer, a two-dimensional (2-D) array transducer, or a curved array transducer.

A new fabrication method for IPMC actuators and application to artificial fingers

Abstract: IPMC (ionic polymer metal composite), a kind of ionic electroactive polymer (EAP), has been used for various applications because it has light weight and can make large bending deformation under low driving voltage. In the present work, thick IPMC films were fabricated by hot-pressing several thin IPMC films and the actuating performance was evaluated. Displacement and maximum load with applied voltage were measured using a displacement measuring system, a load cell and a multimeter. Several cycles of Pt electroless-plating were performed on the IPMC films to improve the actuating performance. Then, SEM (scanning electron microscopy) micrographs and EDS (energy dispersive spectrometer) profiles of the IPMC specimen were examined. To demonstrate the feasibility of IPMC films for medical or robotic applications, the developed IPMC actuators were applied to artificial fingers and tested.

Catheter Position Tracking Methods Using Fluoroscopy and Rotational Sensors

Abstract: Methods for determine the position and rotational orientation of the transducer array of an ultrasound imaging catheter within a patient include imaging the distal end of the catheter using fluoroscopy and determining the angular orientation based upon the shape and dimensions of the image of the transducer array and wire connecting harness. Additional rotational and translational information may be obtained from sensors located at the proximal end of the catheter. By combining position information obtained using fluoroscopy with information from relative rotation/translation sensors, the imaging transducer position and orientation can be determined more accurately. The resulting accurate imaging transducer position information enables combining multiple images from different positions or orientations to generate multi-dimensional images. Catheters including rotation and translation motion sensors at the proximal end, and radio-opaque materials near the distal end can be provided to enhance the methods.

A micro ultrasonic motor using a micro-machined cylindrical bulk PZT transducer

Abstract: In this paper, a micro ultrasonic motor using a micro-machined bulk piezoelectric transducer is introduced. The cylindrical shaped bulk piezoelectric transducer, a diameter of 0.8 mm and a height of 2.2 mm, was developed as stator transducer for traveling wave type ultrasonic motor. The transducer was made of lead zirconate titanate (PZT) bulk ceramics, and formed by micro machining, Ni plating and laser beam cutting process. Using this stator transducer, we have fabricated a cylindrical micro ultrasonic motor, a diameter of 2.0 mm and a height of 5.9 mm. We have also evaluated some characteristics and succeeded in driving the micro ultrasonic motor.

Detection and suppression of wind noise in microphone signals

Abstract: To reliably and consistently detect desirable sounds, a system detects the presence of wind noise based on the power levels of audio signals. A first transducer detects sound originating from a first direction and a second transducer detects sound originating from a second direction. The power levels of the sound are compared. When the power level of the sound received from the second transducer is less than the power level of the sound received from the first transducer by a predetermined value, wind noise may be present. A signal processor may generate an output from one or a combination of the audio signals, based on a wind noise detection.

Living being presence detection system

Abstract: A system for distinguishing between a first condition corresponding to a living subject being directly in contact with an object of interest, and a second condition corresponding to the absence of contact between the living subject and the object of interest. A transducer, which may be a MEMs sensor, is disposed in predetermined relationship to the object of interest and produces a transducer signal responsive to a pressure wave resulting from the living subject being directly in contact the object of interest. A database stores data corresponding to the first condition and may contain additional data corresponding to the second condition. A processor calculates an algorithm of a non-linear short-term frequency-selective energy distribution of the transducer signal over time to produce transducer signal data. An arrangement, which may be a human listener or a processor system, determines a threshold between the first and second conditions in response to the transducer signal data and the first and second data. The direct contact may be a tap or stroking contact by a living subject. The transducer can be disposed within, or on the exterior of, the object of interest.

Experimental characterization of collapse-mode CMUT operation

Abstract: This paper reports on the experimental characterization of collapse-mode operation of capacitive micromachined ultrasonic transducers (CMUTs). CMUTs are conventionally operated by applying a direct current (DC) bias voltage less than the collapse voltage of the membrane, so that the membrane is deflected toward the bottom electrode. In the conventional regime, there is no contact between the membrane and the substrate; the maximum alternating current (AC) displacement occurs at the center of the membrane. In collapse-mode operation, the DC bias voltage is first increased beyond the collapse voltage, then reduced without releasing the collapsed membrane. In collapse-mode operation, the center of the membrane is always in contact with the substrate. In the case of a circular membrane, the maximum AC displacement occurs along the ring formed between the center and the edge of the membrane. The experimental characterization presented in this paper includes impedance measurements in air, pulse-echo experiments in immersion, and one-way optical displacement measurements in immersion for both conventional and collapse-mode operations. A 205-mum times 205-mum 2-D CMUT array element composed of circular silicon nitride membranes is used in the experiments. In pulse-echo experiments, a custom integrated circuit (IC) comprising a pulse driver, a transmit/receive switch, a wideband low-noise preamplifier, and a line driver is used. By reducing the parasitic capacitance, the use of a custom IC enables pulse-echo measurements at high frequencies with a very small transducer. By comparing frequency response and efficiency of the transducer in conventional and collapse regimes, experimental results show that a collapsed membrane can be used to generate and detect ultrasound more efficiently than a membrane operated in the conventional mode. Furthermore, the center frequency of the collapsed membrane can be changed by varying the applied DC voltage. In this study, the center frequency of a collapsed transducer in immersion is shown to vary from 20 MHz to 28 MHz with applied DC bias; the same transducer operates at 10 MHz in the conventional mode. In conventional mode, the maximum peak-to-peak pressure is 370 kPa on the transducer surface for a 40-ns, 25-V unipolar pulse excitation. In collapse mode, a 25-ns, 25-V unipolar pulse generates 590 kPa pressure at the surface of the transducer

A low-cost noncontact capacitance-type level transducer for a conducting liquid

Abstract: In this paper, an attempt has been made to design a low-cost noncontact capacitance-type level sensor for a conducting liquid. The sensor is in the form of a uniform circular cylinder made of insulating material like glass, ceramic, plastic, etc. The sensor is connected with the metallic- or nonmetallic-type liquid storage tank, in which the conducting liquid column is taken as one electrode, and a noninductively wound short-circuited outside coil is taken as the other electrode of a variable capacitor. The change in capacitance due to the change of liquid level is measured by a modified linear operational-amplifier-based De' Sauty bridge network with adjustable bridge sensitivity. The bridge output after amplification and rectification may be used to drive a direct current indicator calibrated in level. The studies have been made with high-density polyethylene and glass tube sensors separately in both metallic and nonmetallic storage tanks with tap water as the conducting liquid, and the experimental results of the static characteristics of the level sensors with percentage error from linearity are presented in the paper. These results are found to have good linearity and repeatability within acceptable limits

Pulsed magnetic flux leakage techniques for crack detection and characterisation

Abstract: Magnetic flux leakage (MFL) techniques have been widely used for non-intrusively inspecting steel installations by applying magnetization. In the situations where defects may take place on the near and far surfaces of the structure under inspection, current MFL techniques are unable to determine their approximate size. Consequently, an extra transducer may have to be included to provide the extra information required. This paper presents a new approach termed as pulsed magnetic flux leakage (PMFL) for crack detection and characterisation. The probe design and method are introduced. The signal features in time–frequency domains are investigated through theoretical simulations and experiments. The results show that the technique can potentially provide additional information about the defects. Lastly, potential applications are suggested.

Medical ultrasound transducer having non-ideal focal region

Abstract: A mechanically formed transducer capable of producing a non-ideal focal region is described. The transducer has a plurality of piezoelectric elements suspended in an epoxy and heat molded into a desired shape. One or more shaped irregularities in the transducer provides for a mechanically induced non-ideal focal field without the need for electronic steering or lens focusing. Systems and methods of making the same are also described.