Showing papers on "Transducer published in 2007"

Initiating medical system communications

Abstract: A medical system includes a body-contacting signal source adapted to transmit an oscillatory signal though a body to a transducer of a device implanted therein. A detector that is coupled to the transducer, upon detection of a response of the transducer to the signal, activates a radio-frequency (RF) telemetry component of the device.

New materials for micro-scale sensors and actuators An engineering review

Abstract: This paper provides a detailed overview of developments in transducer materials technology relating to their current and future applications in micro-scale devices. Recent advances in piezoelectric, magnetostrictive and shape-memory alloy systems are discussed and emerging transducer materials such as magnetic nanoparticles, expandable micro-spheres and conductive polymers are introduced. Materials properties, transducer mechanisms and end applications are described and the potential for integration of the materials with ancillary systems components is viewed as an essential consideration. The review concludes with a short discussion of structural polymers that are extending the range of micro-fabrication techniques available to designers and production engineers beyond the limitations of silicon fabrication technology.

Role of acoustic cavitation in the delivery and monitoring of cancer treatment by high-intensity focused ultrasound (HIFU)

Abstract: Acoustic cavitation has been shown to play a key role in a wide array of novel therapeutic ultrasound applications. This paper presents a brief discussion of the physics of thermally relevant acoustic cavitation in the context of high-intensity focussed ultrasound (HIFU). Models for how different types of cavitation activity can serve to accelerate tissue heating are presented, and results suggest that the bulk of the enhanced heating effect can be attributed to the absorption of broadband acoustic emissions generated by inertial cavitation. Such emissions can be readily monitored using a passive cavitation detection (PCD) scheme and could provide a means for real-time treatment monitoring. It is also shown that the appearance of hyperechoic regions (or bright-ups) on B-mode ultrasound images constitutes neither a necessary nor a sufficient condition for inertial cavitation activity to have occurred during HIFU exposure. Once instigated at relatively large HIFU excitation amplitudes, bubble activity tends to grow unstable and to migrate toward the source transducer, causing potentially undesirable pre-focal damage. Potential means of controlling inertial cavitation activity using pulsed excitation so as to confine it to the focal region are presented, with the intention of harnessing cavitation-enhanced heating for optimal HIFU treatment delivery. The role of temperature elevation in mitigating bubble-enhanced heating effects is also discussed, along with other bubble-field effects such as multiple scattering and shielding.

Contact-Free Measurement of Cardiac Pulse Based on the Analysis of Thermal Imagery

Abstract: We have developed a novel method to measure human cardiac pulse at a distance. It is based on the information contained in the thermal signal emitted from major superficial vessels. This signal is acquired through a highly sensitive thermal imaging system. Temperature on the vessel is modulated by pulsative blood flow. To compute the frequency of modulation (pulse), we extract a line-based region along the vessel. Then, we apply fast Fourier transform (FFT) to individual points along this line of interest to capitalize on the pulse's thermal propagation effect. Finally, we use an adaptive estimation function on the average FFT outcome to quantify the pulse. We have carried out experiments on a data set of 34 subjects and compared the pulse computed from our thermal signal analysis method to concomitant ground-truth measurements obtained through a standard contact sensor (piezo-electric transducer). The performance of the new method ranges from 88.52% to 90.33% depending on the clarity of the vessel's thermal imprint. To the best of our knowledge, it is the first time that cardiac pulse has been measured several feet away from a subject with passive means.

A nonlinear model for ionic polymer metal composites as actuators

Abstract: This paper introduces a comprehensive nonlinear dynamic model of motion actuators based on ionic polymer metal composites (IPMCs) working in air. Significant quantities ruling the acting properties of IPMC-based actuators are taken into account. The model is organized as follows. As a first step, the dependence of the IPMC absorbed current on the voltage applied across its thickness is taken into account; a nonlinear circuit model is proposed to describe this relationship. In a second step the transduction of the absorbed current into the IPMC mechanical reaction is modelled. The model resulting from the cascade of both the electrical and the electromechanical stages represents a novel contribution in the field of IPMCs, capable of describing the electromechanical behaviour of these materials and predicting relevant quantities in a large range of applied signals. The effect of actuator scaling is also investigated, giving interesting support to the activities involved in the design of actuating devices based on these novel materials. Evidence of the excellent agreement between the estimations obtained by using the proposed model and experimental signals is given.

Ultrasonic Through-Wall Communication (UTWC) System

Abstract: Apparatus for communicating information across a solid wall has one or two outside ultrasonic transducers coupled to an outside surface of the wall and connected to a carrier generator for sending an ultrasonic carrier signal into the wall and for receiving an output information signal from the wall. One or two inside ultrasonic transducers are coupled to an inside surface of the wall and one of them introduces the output information signal into the wall. When there are two inside transducers inside the wall, one receives the carrier signal and the second transmits the carrier after it is modulated by the output information from the sensor. When there is one inside transducer, the output information from the sensor is transmitted by changing the reflected or returned signal from the inside transducer. A power harvesting circuit inside the wall harvests power from the carrier signal and uses it to power the sensor.

Piezoelectric materials for high frequency medical imaging applications: A review

Abstract: The performance of transducers operating at high frequencies is greatly influenced by the properties of the piezoelectric materials used in their fabrication. Selection of an appropriate material for a transducer is based upon many factors, including material properties, transducer area, and frequency of operation. This review article outlines the major developments in the field of piezoelectrics with emphasis on materials suitable for the design of high frequency medical imaging ultrasonic transducers. Recent developments in the areas of fine grain and thin film ceramics, piezo-polymers, single crystal relaxor piezoelectrics, as well as lead-free and composite materials are discussed.

Consideration of Impedance Matching Techniques for Efficient Piezoelectric Energy Harvesting

Abstract: This study investigates multiple levels of impedance-matching methods for piezoelectric energy harvesting in order to enhance the conversion of mechanical to electrical energy. First, the transduction rate was improved by using a high piezoelectric voltage constant (g) ceramic material having a magnitude of g33 = 40 times 10-3 V m/N. Second, a transducer structure, cymbal, was optimized and fabricated to match the mechanical impedance of vibration source to that of the piezoelectric transducer. The cymbal transducer was found to exhibit ~40 times higher effective strain coefficient than the piezoelectric ceramics. Third, the electrical impedance matching for the energy harvesting circuit was considered to allow the transfer of generated power to a storage media. It was found that, by using the 10-layer ceramics instead of the single layer, the output current can be increased by 10 times, and the output load can be reduced by 40 times. Furthermore, by using the multilayer ceramics the output power was found to increase by 100%. A direct current (DC)-DC buck converter was fabricated to transfer the accumulated electrical energy in a capacitor to a lower output load. The converter was optimized such that it required less than 5 mW for operation.

Silicon condenser microphone and manufacturing method

Abstract: A silicon condenser microphone package is disclosed. The silicon condenser microphone package comprises a transducer unit, substrate, and a cover. The substrate includes an upper surface having a recess formed therein. The 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 includes an aperture.

A parallel tracking method for acoustic radiation force impulse imaging

Abstract: Radiation force-based techniques have been developed by several groups for imaging the mechanical properties of tissue. Acoustic radiation force impulse (ARFI) imaging is one such method that uses commercially available scanners to generate localized radiation forces in tissue. The response of the tissue to the radiation force is determined using conventional B-mode imaging pulses to track micron-scale displacements in tissue. Current research in ARFI imaging is focused on producing real-time images of tissue displacements arid related mechanical properties. Obstacles to producing a real-time ARFl imaging modality include data acquisition, processing power, data transfer rates, heating of the transducer, and patient safety concerns. We propose a parallel receive beamforming technique to reduce transducer heating and patient acoustic exposure, and to facilitate data acquisition for real-time ARFI imaging. Custom beam sequencing was used with a commercially available scanner to track tissue displacements with parallel-receive beamforming in tissue-mimicking phantoms. Using simulations, the effects of material properties on parallel tracking are observed. Transducer and tissue heating for parallel tracking are compared to standard ARFI beam sequencing. The effects of tracking beam position and size of the tracked region are also discussed in relation to the size and temporal response of the region of applied force, and the impact on ARFI image contrast arid signal-to-noise ratio are quantified

Display with integrated audio transducer device

Abstract: Systems and methods that integrate audio capabilities within a display. A multilayered arrangement of dielectric and conductive layers can form a transducer that is integrated into the display. The dielectric layer can subsequently be charged (e.g., a biased voltage) and subject to a voltage to produce distortions and/or deflections of the dielectric layer, to produce acoustic waves that are audible to a user.

Method for defining a touch-down power for head having a flying height actuator

Abstract: A novel method for defining a touch-down power for a head that has a head-based flying height actuator is disclosed and claimed. A linear relationship between power and spacing is derived by fitting to first and second transducer-disk spacings corresponding to first and second electrical powers applied to the head-based flying height actuator. A third spacing between the transducer and the disk is determined when a greater third electrical power is applied to the flying height actuator. An estimated third spacing between the transducer and the disk, corresponding to application of the third electrical power to the flying height actuator, is calculated using the derived linear relationship and the third electrical power. The touch-down power is defined to be substantially equal to the second electrical power if an error between the third spacing and the estimated third spacing is larger than a first threshold.

PMN-PT single crystal, high-frequency ultrasonic needle transducers for pulsed-wave Doppler application

Abstract: High-frequency needle ultrasound transducers with an aperture size of 0.4 mm were fabricated using lead magnesium niobate-lead titanate (PMN-33%PT) as the active piezoelectric material. The active element was bonded to a conductive silver particle matching layer and a conductive epoxy backing through direct contact curing. An outer matching layer of parylene was formed by vapor deposition. The active element was housed within a polyimide tube and a 20-gauge needle housing. The magnitude and phase of the electrical impedance of the transducer were 47 Omega and -38deg, respectively. The measured center frequency and -6 dB fractional bandwidth of the PMN-PT needle transducer were 44 MHz and 45%, respectively. The two-way insertion loss was approximately 15 dB. In vivo high-frequency, pulsed-wave Doppler patterns of blood flow in the posterior portion and in vitro ultrasonic backscatter microscope (UBM) images of the rabbit eye were obtained with the 44-MHz needle transducer

SU-8 MEMS Fabry-Perot pressure sensor

Abstract: The biocompatible polymer, SU-8, was used to microfabricate an interferometric pressure sensor designed for invasive biomedical applications. Tests of the sensor in air and liquid environments show promising results as well as the limitations of SU-8 as a critical material in microdevices. The sensor consists of a polymer cap with a reflective, pressure-sensing diaphragm mounted onto the end of a fiber optic cable. Diaphragm deflection was measured by analyzing the spectrum reflected from the Fabry-Perot interferometer formed between the diaphragm and the fiber end. The device is fast, simple, and inexpensive to manufacture. Its small dimensions (300 μm outer diameter) reduce the risk of inflammation and infection and allow for its insertion through a catheter into small vessels and cavities. The sensor showed a linear pressure response from 0 to 125 mmHg with 1–2 mmHg resolution. The cap swelled upon immersion in a manner consistent with Fickian diffusion of water into SU-8. The interferometric displacement transducer allowed a series of measurements to characterize the drift and hysteresis of the SU-8 sensors in different environments. These results provide guidance for the design and manufacture of SU-8 microdevices.

Perpendicular magnetic recording head having a recessed magnetic base layer

Abstract: A method and system for providing a magnetic transducer having an air-bearing surface (ABS) are described The magnetic transducer includes a base layer, a perpendicular magnetic recording (PMR) pole on the base layer, an additional pole, a write shield, a write gap between the PMR pole and a portion of the write shield, and coil(s) that energize at least the additional pole The base layer includes a first portion proximate to the ABS and a second portion recessed from the ABS The first portion is nonmagnetic, while the second portion is magnetic The PMR pole has a first front portion proximate to the ABS The additional pole has a second front portion recessed from the ABS At least a portion of the additional pole resides between the PMR pole and write shield At least a portion of the write gap resides on the front portion of the PMR pole

Magnetic writer having a split yoke

Abstract: A method and system for providing a magnetic transducer are described. The magnetic transducer includes a first pole, a write gap, a second pole, a first coil, and a second coil. The first pole has a front portion on which at least a portion of the write gap resides. The second pole includes a split yoke that includes a first portion and a second portion. At least a portion of the first coil resides between the first portion of the split yoke and the first pole. At least a portion of the second coil resides between the second portion of the split yoke and the first pole.

Performance limits of the three MEMS inertial energy generator transduction types

Abstract: In this paper, trends from the last 10 years of inertial micro-generator literature are investigated and it is shown that, although current generator designs are still operating well below their maximum power, there has been a significant improvement with time. Whilst no clear conclusions could be drawn from reported fabricated devices with respect to preferred transducer technology, this paper presents operating charts for inertial micro-generators which identify optimal operating modes for different frequencies and normalized generator sizes, and allows comparison of the different transduction mechanisms as these parameters vary. It is shown that piezoelectric generators have a wider operating range at low frequency than electromagnetic generators, but as generator dimensions increase, the frequency to which piezoelectric transducers outperform electromagnetic transducers decreases.

A Broadband WR10 Turnstile Junction Orthomode Transducer

Abstract: We present a broadband waveguide ortho-mode transducer for the WR10 band that was designed for CLOVER, an astrophysics experiment aiming to characterize the polarization of the cosmic microwave background radiation. The design, based on a turnstile junction, was manufactured and then tested using a millimeter-wave vector network analyzer. The average measured return loss and isolation were -22 dB and -45 dB, respectively, across the entire WR10 band

Fast full-view photoacoustic imaging by combined scanning with a linear transducer array

Abstract: We present a fast full-view photoacoustic imaging system for visualizing tissue structures using a linear transducer array with combined scan. In this system, a 128-element linear transducer array was used to detect photoacoustic signals by combined scanning of electronic scan and mechanical scan. An improved limited-field filtered back projection algorithm with directivity factors was applied to reconstruct the optical absorption distribution. The experiments of phantoms and in vivo blood vessels in a rat brain were performed with this system. And a clear view of the curve boundaries of objects and the network of blood vessels of rat's brain were acquired. The experimental results demonstrate the multi-element photoacoustic imaging system has the ability of imaging complicated structures of objects.

Finger-mounted or robot-mounted transducer device

Abstract: A transducer device for therapeutic applications is disclosed. The transducer device may include a mounting body configured for mounting the device to a finger of an operator of the device. The transducer device may also include a transducer housing connected to the mounting body that defines a receiving portion. The transducer device may further include a transducer element disposed in the receiving portion that is configured for connection to an energy supply and configured to transmit energy from an emitting surface. The transducer device may further include a gas reservoir disposed between the transducer element and the mounting body that is configured to prevent transmission of energy. The transducer device may further include a membrane connected to the transducer housing and disposed adjacent the emitting surface of the transducer element, and a cooling lumen for providing fluid to the membrane. A method of applying therapeutic ultrasound is also disclosed.

Optical data link

Abstract: The invention provides an optically powered device interface module for operating an external device, and an optically powered data link comprising the same. In one embodiment the device interface module includes an optical interface for receiving optical power and data signals, an electrical USB interface for providing USB compliant electrical data signals and a 5V electrical power signal to an external USB device, a transducer coupled to a signal processor for converting the optical power and data signals into the 5V electrical power signal and the USB-compliant electrical data signals, and a power distribution circuit for providing electrical power obtained from the optical power signal to the device interface module circuitry. The transducer may be embodied using a single photovoltaic power converter for receiving the optical power and for receiving and transmitting optical data signals.

Method and system for real-time signal classification

Abstract: A method to achieve an accurate, extremely low power state classification implementation is disclosed. Embodiments include a sequence that matches the data flow from the sensor transducer, through analog filtering, to digital sampling, feature computation, and classification.

A CMOS Single-Chip Electronic Compass with Microcontroller

Abstract: We present a CMOS single-chip electronic compass sensor including the complete digital signal processing for accurate heading calculation. The device's analog part consists of Hall- based three-axis magnetic field transducer with integrated magnetic concentrator that operates as a passive magnetic amplifier. The analog amplification chain features a gain of up to 20 000. A true-12-bit extended counting ADC converts the amplified magnetic field signals into the digital domain, where a 16-bit microcontroller calculates the heading information and outputs it via an SPI interface. The compass sensor is realized in 0.35 mum low-voltage CMOS technology plus a simple batch processing step for deposition of a metal layer. The compact die size of 2.3 mm times 2.8 mm allows for packaging into a standard 4 mm times 5 mm times 1 mm surface-mount plastic package. The heading resolution is better than 0.5deg, and the accuracy better than plusmn2deg.

Method and system for using common subchannel to assess the operating characteristics of transducers

Abstract: A system and method for using a common subchannel to assess operating characteristics of one of a plurality of transducers that are coupled to said subchannel is disclosed. The plurality of transducers are divided into subsets and each subset is coupled to a subchannel. The system is configured to activate a selected transducer on the subchannel and the subchannel delivers operational information on the activated transducer. The present invention reduces the number of subchannels required to collect information on the plurality of transducers. The present invention may utilize one or more loading conditions to take at least one measurement, which at least one measurement is then used to derive operational information on the transducer. In one configuration, information on the amount of energy being delivered to the transducer is collected simultaneously with information on the operating temperature. In another embodiment only the temperature is measured. The present invention permits a more compact ablation device to be constructed based on the invention's ability to reduce the total number of subchannels required to collect transducer information.

Vibrotactile transduction and transducers.

Abstract: The body’s sense of touch is potentially a versatile channel for the conveyance of directional, spatial, command, and timing information. Most practical implementations of vibrotactile systems require compact, light-weight actuators that can be mounted against the body. Eccentric mass motors are widely used for this application, yet their output is limited and the effects of loading on the transducers due to the skin and mounting arrangement have been largely ignored. Conventional linear actuators are well suited as vibrotactile transducers and can provide high output, but are typically limited to laboratory research due to their large size and cost. The effect of loading on various practical vibrotactile transducers is investigated using a skin impedance phantom and measuring the transducer displacement with respect to additional mass loading. Depending on the transducer design, loading can dramatically reduce the vibratory displacement and, in the case of eccentric mass motors, also increase the operating frequency. In contrast, a new linear actuator design can be designed to be almost independent of skin loading, by considering the mechanical impedance of the load and optimizing the transducer contact area.

Method and device for three-dimensional sensing

Abstract: An apparatus ( 100 ) and method is provided that identifies and tracks a relative location and movement of an object in a three-dimensional space. The sensing unit includes a processor ( 122 ) for communicating a coordinate information of the object within the three-dimensional space. The method includes emitting a pulse from a first transducer ( 101 ), estimating a time of flight from a reflection signal received by a second transducer ( 102 ), and determining a location and relative movement of the object from the time of flight measurements. The sensing unit can provide touchless control via touchless finger depression actions, finger slide actions, finger release actions, and finger hold actions.

Broadband all-optical ultrasound transducers

Abstract: A broadband all-optical ultrasound transducer has been designed, fabricated, and tested for high-resolution ultrasound imaging. It consists of a two-dimensional gold nanostructure on a glass substrate, followed by a 3μm polydimethylsiloxane layer and a 30nm gold layer. The signal to noise ratio of a pulse-echo signal is over 10dB in the far field of the transducer, where the center frequency is 40MHz with −6dB bandwidth of 57MHz. The potential for high-frequency ultrasound arrays using this technology is demonstrated using multiple measurements from the transducer to image a 25μm diameter wire.

Active noise cancellation in hearing devices

Abstract: Disclosed is a hearing device system comprising at least one hearing aid circuitry and at least one active noise cancellation unit, the at least one hearing aid circuitry comprises at least one input transducer adapted to convert a first audio signal to an electric audio signal; a signal processor connected to the at least one input transducer and adapted to process said electric audio signal by at least partially correcting for a hearing loss of a user; an output transducer adapted to generate from at least said processed electric audio signal a sound pressure in an ear canal of the user, whereby the generated sound pressure is at least partially corrected for the hearing loss of the user; the at least one active noise cancellation unit being adapted to provide an active noise cancellation signal adapted to perform active noise cancellation of an acoustical signal entering the ear canal in addition to said generated sound pressure, wherein the hearing device system further comprises a combiner unit adapted to combine the processed electric audio signal with the active noise cancellation signal, to obtain a combined signal and to provide the combined signal to the output transducer.

Modeling the excitation of guided waves in generally anisotropic multilayered media

Abstract: The design of transducers to excite and detect guided waves is a fundamental part of a nondestructive evaluation or structural health monitoring system and requires the ability to predict the radiated guided wave field of a transmitting transducer. For most transducers, this can be performed by making the assumption that the transducer is weakly coupled and then integrating the Green’s function of the structure over the area of the transducer. The majority of guided wave modeling is based on two-dimensional (2D) formulations where plane, straight-crested waves are modeled. Several techniques can be readily applied to obtain the solution to the forced 2D problem in terms of modal amplitudes. However, for transducer modeling it is desirable to obtain the complete three-dimensional (3D) field, which is particularly challenging in anisotropic materials. In this paper, a technique for obtaining a far-field asymptotic solution to the 3D Green’s function in terms of the modal solutions to the forced 2D problem i...

Targeting location through haptic feedback signals

Abstract: A data processing apparatus and a method of operating a data processing apparatus are disclosed. The data processing apparatus comprises a memory for storing target location data representative of the location of a target, a position determining component configured to generate a position signal representative of a position of the data processing apparatus, and an orientation determining component configured to generate an orientation signal representative of an orientation of the data processing apparatus. The data processing apparatus also comprises a haptic transducer configured to provide haptic feedback to a user of the data processing apparatus and a processor configured to process the target location data, position signal and orientation signal in order to generate a transducer control signal that is configured to actuate the haptic transducer to provide directional haptic feedback to a user relative to the target location.