Showing papers on "Transducer published in 2002"

Spiral scanner with electronic control

Abstract: A scanning device, typically ultrasonic, can make a volumetric scan of a conical scanning field. A transducer having a permanent magnet at its back end is gimbal mounted in a housing. Behind the permanent magnet is a hemispheric electromagnet coil assembly having at least two wound electromagnet coils. The coils are energized in turn with an alternating current signal, with the signal applied to any coil being out of phase with the signal applied to any other coil by 180°/n, where n is the number of coils in the hemispheric electromagnet coil assembly. Volumetric scanning is possible by periodically modulating the magnitude or frequency of the signals applied to the coils.

System for combined transcutaneous blood gas monitoring and vacuum assisted wound closure

Abstract: A method and apparatus for the transcutaneous monitoring of blood gases generally comprises a blood gas data acquisition device, a vacuum source and a blood gas transducer unit. The blood gas transducer unit is adapted for application to a patient's skin and administration of a local vacuum at the area of patient application. It further comprises an electrochemical blood gas transducer, well known to those of ordinary skill in the art, which is disposed entirely within the local vacuum at the area of patient application. The vacuum source is placed in fluid communication with the blood gas transducer unit, through a hydrophobic membrane filter for safety purposes, in order to induce a condition of hyperperfusion in the locality of the electrochemical blood gas transducer. Under the control of a microcontroller, or equivalent means, the blood gas acquisition device is then utilized to capture a measure of skin surface oxygen or carbon dioxide pressure. The microcontroller can then utilize this measure to arrive at an estimate of arterial partial pressure of oxygen or carbon dioxide, accordingly. Because vacuum induced perfusion produces the requisite condition of hyperperfusion without local heating and, therefore, without acceleration of the local metabolic function, the present invention results in more accurate than previously available estimates of partial pressure blood gas pressures and does so while eliminating a significant risk for injury to the patient.

A non-invasive method for focusing ultrasound through the human skull

Abstract: A technique for focusing ultrasound through the human skull is described and verified. The approach is based on a layered wavevector-frequency domain model, which propagates ultrasound from a hemisphere-shaped transducer through the skull using input from CT scans of the head. The algorithm calculates the driving phase of each transducer element in order to maximize the signal at the intended focus. This approach is tested on ten ex vivo human skulls using a 0.74 MHz, 320-element array. A stereotaxic reference frame is affixed to the skulls in order to provide accurate registration between the CT images and the transducer. The focal quality is assessed with a hydrophone placed inside the skull. In each trial the phase correction algorithm successfully restored the focus inside the skull at a location within 1 mm from the intended focal point. The results demonstrate the feasibility of using the method for completely non-invasive ultrasound brain surgery and therapy.

Medical imaging and navigation system

Abstract: Medical imaging and navigation system including a processor, a display unit, a database, a medical positioning system (MPS), a two-dimensional imaging system, an inspected organ monitor interface, and a superimposing processor, the MPS including a transducer MPS sensor and a surgical tool MPS sensor, the two-dimensional imaging system including an imaging transducer, the processor being connected to the display unit, to the database, to the MPS, to the two-dimensional imaging system, to the inspected organ monitor interface, and to the superimposing processor, the inspected organ monitor interface being connected to an organ monitor, the surgical tool MPS sensor being firmly attached to a surgical tool, the transducer MPS sensor being firmly attached to the imaging transducer, the organ monitor monitoring an organ timing signal associated with an inspected organ.

Shear elasticity probe for soft tissues with 1-D transient elastography

Abstract: Important tissue parameters such as elasticity can be deduced from the study of the propagation of low frequency shear waves. A new method for measuring the shear velocity in soft tissues is presented in this paper. Unlike conventional transient elastography in which the ultrasonic transducer and the low frequency vibrator are two separated parts, the new method relies on a probe that associates the vibrator and the transducer, which is built on the axis of the vibrator. This setup is easy to use. The low frequency shear wave is driven by the transducer itself that acts as a piston while it is used in pulse echo mode to acquire ultrasonic lines. The results obtained with the new method are in good agreement with those obtained with the conventional one.

Imaging, therapy, and temperature monitoring ultrasonic system

Abstract: An ultrasonic system useful for providing imaging, therapy and temperature monitoring generally comprises an acoustic transducer assembly configured to enable the ultrasound system to perform the imaging, therapy and temperature monitoring functions. The acoustic transducer assembly comprises a single transducer that is operatively connected to an imaging subsystem, a therapy subsystem and a temperature monitoring subsystem. The ultrasound system may also include a display for imaging and temperature monitoring functions. An exemplary single transducer is configured such that when connected to the subsystems, the imaging subsystem can generate an image of a treatment region on the display, the therapy subsystem can generate high power acoustic energy to heat the treatment region, and the temperature monitoring subsystem can map and monitor the temperature of the treatment region and display the temperature on the display, all through the use of the single transducer. Additionally, the acoustic transducer assembly can be configured to provide three-dimensional imaging, temperature monitoring or therapeutic heating through the use of adaptive algorithms and/or rotational or translational movement. Moreover, a plurality of the exemplary single transducers can be provided to facilitate enhanced treatment capabilities.

Variable multi-dimensional apodization control for ultrasonic transducers

Abstract: Variable multi-dimensional apodization control (200) for an ultrasonic transducer array (202) is disclosed The variable multi-dimensional apodization control (200) is applicable to both piezoelectric based transducers and to MUT based transducers and allows control of the apodization profile of an ultrasonic transducer array (202) having elements arranged in more than one dimension

Articulating ultrasonic surgical shears

Abstract: A therapeutic ultrasound instrument is described for cutting, dissecting, or cauterizing tissue. Ultrasonic vibrations, when transmitted to organic tissue at suitable energy levels and using a suitable end-effector, may be used for the safe and effective treatment of many medical conditions. An ultrasonic surgical instrument is described which incorporates an articulating shearing end-effector. The instrument comprises an ultrasonic transducer, an ultrasonically activatable end-effector, and a substantially solid ultrasonic waveguide that connects the ultrasonic transducer to the end-effector. The waveguide comprises a transmission section extending from the transducer to a fixed node, and an articulation section extending from the fixed node to a pivoting node. The end-effector includes a bifurcated waveguide segment. A handle is adapted to hold the transducer. An outer sheath extends from the handle to the end-effector and surrounds the waveguide. An actuation trigger is rotatably positioned on the handle, and an actuation arm extends from a distal end of the actuation trigger to the pivoting node. Such instruments are particularly suited for use in minimally invasive procedures, such as endoscopic or laparoscopic procedures.

An all-organic sensor-transistor based on a novel electrochemical transducer concept printed electrochemical sensors on paper

Abstract: A novel transducer concept based on an organic electrochemical transistor is described. Its function as an integral part of an air humidity sensor, in which the proton conductor Nafion acts as sensitivity layer has been realised. The resulting electrochemical sensor–transistor, based on the conducting polymer PEDOT:PSS, operates at low voltages, on the order of 1 V. The sensor response, measured as the drain–source current of the electrochemical transistor, versus air humidity, has a close to exponential behaviour. The sensor can be realised using exclusively printing and coating fabrication techniques. Here, we demonstrate devices realised on plastic foils and on ordinary coated fine paper substrates. This organic electrochemical transducer promise future applications such as all-integrated low-cost sensor tags for single-use chemical sensors.

A laser-micromachined multi-modal resonating power transducer for wireless sensing systems

Abstract: This paper presents the development of a vibration-induced power generator with total volume of ∼1 cm 3 which uses laser-micromachined springs to convert mechanical energy into useful electrical power by Faraday’s law of induction. The goal of this project is to create a minimally sized electric power generator capable of producing enough voltage to drive low-power ICs and/or microsensors for applications where ambient mechanical vibrations are present. Thus far, we have fabricated generators with total volume of 1 cm 3 that are capable of producing up to 4.4 V peak-to-peak, which have a maximum RMS power of ∼830 μW with loading resistance of 1000 Ω. The mechanical vibration required to generate this electrical energy has frequencies ranging from 60 to 110 Hz with ∼200 μm amplitude. The generator was shown to generate sufficient power at different resonating modes. We have demonstrated that this generator can drive an infrared (IR) transmitter to send 140 ms pulse trains every minute, and also a 914.8 MHz FM wireless temperature sensing system.

Ultrasonic catheter drug delivery method and device

Abstract: An ultrasonic catheter drug delivery device comprises an ultrasound transducer to produce ultrasonic waves, which transducer is mechanically attached to a catheter body or chamber. The ultrasonic transducer has a distal tip with a distal radiation surface, and when a therapeutic agent from a fluid source is directed to the catheter body or chamber, the radiation surface creates ultrasonic pressure and delivers liquid and simultaneously ultrasonic energy to a patient's vascularity or a selected body lumen. The method applies therapeutic agent and ultrasonic waves to the vascular area, lung or any body lumen without requiring direct contact between ultrasound transducer and body, dissolves blood clots, and stimulates tissue cells.

Variable stiffness electroactive polymer systems

Abstract: The invention relates to systems that provide variable stiffness and/or variable damping using an electroactive polymer transducer. Systems described herein offer several techniques that provide variable and controlled stiffness and/or damping. A transducer may be implemented using open loop control, thereby providing simple systems that inactively deliver a desired stiffness and/or damping performance. Alternately, closed loop control techniques permit electroactive polymer transducer designs that actively adapt the stiffness and/or damping performance of a system. Further, transducers may be implemented in a device whose stiffness changes with deflection of the polymer.

Ultrasonic medical treatment device for RF cauterization and related method

Abstract: An ultrasonic medical treatment device has a casing, an elongate probe, a transducer assembly, a sheath and at least one electrode member. The probe is mounted to and extends from the casing and has an axis and a free end serving as an operative tip. The transducer assembly is mounted to the casing and is operatively connected to the probe for generating vibrations of at least one ultrasonic frequency in the probe. The sheath surrounds the probe. The electrode member is connectable to an RF voltage source and is mounted at least indirectly to the casing so as to permit relative motion between the electrode member and the probe.

Electromechanical modeling and characterization of ionic polymer benders

Abstract: This paper presents a coupled, electromechanical model of a Nafion-based ionic polymer transducer used in the cantilevered bender configuration. A comparison of simulatedandexperimental responses for a 0.2 mm 5.0 mm 17 mm actuator validates both the form of the model and the empirically determined model parameters. In one of the experiments used for parameter identification, the short circuit current is found to be proportional to the induced actuator velocity, with the constant of proportionality on the order of 104A/(m/s). This dynamic model differs from those presented by other researchers in that it is able to represent the transducer as either a sensor or as an actuator. Also presented is an assessment of the polymer actuators’ ability to perform mechanical work. The results of a series of force versus deflection experiments are outlined, and energy densities are calculated to facilitate comparison with other actuator technologies. The maximum blockedforce with a 1.25 V step input was 1.6 mN (with a ...

Improved design for an automated tension infiltrometer

Abstract: Automated measurements of water infiltration rates are commonly done using two gage transducers to measure water level changes in the reservoir of an infiltrometer Previous studies have evaluated and described in detail infiltrometers automated with two gage-transducers and have shown that measurement precision and accuracy of soil hydraulic properties are improved A previous study has also suggested the use of a single differential transducer to automate an infiltrometer to eliminate measurement error associated with air bubbles in the infiltrometer reservoir In this study, the automation of a tension infiltrometer using a differential transducer was developed, evaluated, and applied A single differential transducer was installed at the bottom of an infiltrometer reservoir and the other end was connected by tubing to the head-space in the reservoir Calibration of the reservoir height measurements vs transducer voltage output was simplified over previous methods and was even demonstrated in situ Measurement precision was also improved by two orders of magnitude over previous methods Measurements were also done to demonstrated the use of the single differential transducer set-up to obtain field measurements of unsaturated hydraulic conductivity and sorptivity Unlike previous methods though, this method does not allow for the determination of the imposed potential at the soil surface unless adaptations are made

Inductive transducer with reduced pole tip protrusion

Abstract: An inductive transducer has inorganic nonferromagnetic material disposed in an apex region adjacent to a submicron nonferromagnetic gap in a magnetic core. The inorganic nonferromagnetic material has a much lower coefficient of thermal expansion than that of hardbaked photoresist, reducing pole tip protrusion even if other insulation surrounding the coil sections within the core is made of hardbaked photoresist. Alternatively, the entire insulation surrounding the coil sections within the core, in addition to the apex region, can be formed of inorganic nonferromagnetic material, further reducing pole tip protrusion. The transducer has SiO2 rather than alumina in an undercoat layer joining the wafer substrate and the thin film layers of the transducer. SiO2 may also replace alumina in other areas, such as a piggyback layer joining the inductive transducer with a magnetoresistive transducer.

Low power consumption implantable pressure sensor

Abstract: Pressure-measuring apparatus (100) is provided, including a battery (118) and a pressure transducer (114). The pressure transducer (114) is adapted to be placed in a patient, and has a characteristic mechanical response bandwidth f, and a corresponding mechanical response period p equal to 1/f. A control unit (102) is adapted to actuate the battery (118) to drive current through the pressure transducer (114) for a current-driving time period less than 0.5 p, and to sense an electrical characteristic of the pressure transducer (114) during the current-driving time period.

System for measuring a biological parameter by means of photoacoustic interaction

Abstract: A system for measuring a biological parameter, such as blood glucose, the system comprising the steps of directing laser pulses from a light guide into a body part consisting of soft tissue, such as the tip of a finger to produce a photoacoustic interaction The resulting acoustic signal is detected by a transducer and analyzed to provide the desired parameter

Silicon-based transducer for use in hearing instruments and listening devices

Abstract: A silicon-based transducer assembly coupled to a movable structure in a hearing instrument. The transducer assembly includes at least one microphone chip and an ASIC having multiple integrated components such as any combination of a DSP, an A/D converter, an amplifier, a filter, or a wireless interface. The movable structure may be a battery access door, a volume dial, a switch, or a touch pad. A protection strip can be disposed across the battery access door to prevent debris from clogging the silicon-based transducer assembly. The transducer assembly may also include an array of microphone chips to achieve adaptive beam steering or directionality. When equipped with a wireless interface, the hearing instrument wirelessly communicates with another hearing instrument or with a network.

Method and apparatus for controlling ultrasonic transducer

Abstract: Method and apparatus for implementing ultrasonic systems that maximize efficiency by dynamically detecting and maintaining peak operational resonance frequency. In one embodiment, the invention dynamically sweeps the output frequency range to locate the peak load current. The resonance frequency corresponding to the peak load current is used as a reference frequency in a control loop. The control loop includes a voltage-controlled oscillator (VCO) that is controlled by a loop controller and operates to lock onto the dynamically sensed reference frequency. In response to the VCO output, a pulse-width modulator (PWM) circuit drives a pair of switches that adjust transducer current to maintain the circuit locked on the resonance frequency at a substantially constant current.

System and method for electronically altering ultrasound scan line origin for a three-dimensional ultrasound system

Abstract: A system and method for individually varying the orientation of scan lines in at least two dimensions in an ultrasound scan are disclosed. In one embodiment, the invention includes a system for generating a three-dimensional ultrasound volume scan, comprising a transducer probe having elements arranged in a plurality of dimensions and a system controller capable of generating a scan line apparently emanating from a location other than the geographic center of the transducer probe.

Wireless communication over a transducer device

Abstract: One aspect of the present invention is generally directed towards a system and method of tuning a transducer for transmitting and receiving a wireless signal. In an illustrative embodiment, a single transducer is coupled to a first or second circuit for either transmitting or receiving, respectively. Generally, electrical characteristics of the first circuit are adjusted to increase a magnetic field generated by the transducer. Conversely, electrical characteristics of the second circuit are adjusted to increase a signal generated by the transducer for receiving a magnetic field. Accordingly, a single transducer device can be tuned for either transmitting or receiving a corresponding wireless signal.

Active vibroacoustic control with multiple local feedback loops.

Abstract: When multiple actuators and sensors are used to control the vibration of a panel, or its sound radiation, they are usually positioned so that they couple into specific modes and are all connected together with a centralized control system. This paper investigates the physical effects of having a regular array of actuator and sensor pairs that are connected only by local feedback loops. An array of 4×4 force actuators and velocity sensors is first simulated, for which such a decentralized controller can be shown to be unconditionally stable. Significant reductions in both the kinetic energy of the panel and in its radiated sound power can be obtained for an optimal value of feedback gain, although higher values of feedback gain can induce extra resonances in the system and degrade the performance. A more practical transducer pair, consisting of a piezoelectric actuator and velocity sensor, is also investigated and the simulations suggest that a decentralized controller with this arrangement is also stable over a wide range of feedback gains. The resulting reductions in kinetic energy and sound power are not as great as with the force actuators, due to the extra resonances being more prominent and at lower frequencies, but are still worthwhile. This suggests that an array of independent modular systems, each of which included an actuator, a sensor, and a local feedback control loop, could be a simple and robust method of controlling broadband sound transmission when integrated into a panel.

Surface mountable transducer system

Abstract: The present invention relates to a surface mountable acoustic transducer system, comprising one or more transducers, a processing circuit electrically connected to the one or more transducers, and contact points arranged on an exterior surface part of the transducer system. The contact points are adapted to establish electrical connections between the transducer system and an external substrate, the contact points further being adapted to facilitate mounting of the transducer system on the external substrate by conventional surface mounting techniques.

Focused ultrasound system with mri synchronization

Abstract: A MRI system (50) uses a timing sequence for transmitting radio frequency (RF) signals and detecting magnetic resonance (MR) response signals from a patient's body in response to the RF pulse sequences. A piezoelectric transducer (14) is driven with drive signals such that the transducer emits acoustic energy towards a target tissue region (42) within the patient's body (40). Parameters of the drive signals are changed at times during the timing sequence that minimize interference with the MRI system detecting MR response signals, e.g., during transmission of RF signals by the MRI system.

Vehicle accessory microphone

Abstract: A microphone assembly (1700) includes one or more transducers (1702) positioned in a housing (1732). Circuitry (Fig. 8) is coupled to the transducer for outputting an electrical signal such that the microphone has a main lobe directed forwardly and attenuates signals originating from the sides and/or rear. The transducers can advantageously include multiple transducers, which, with the circuit, produce a desired sensitivity pattern. The microphone assembly can be employed in a vehicle accessory.

Ultrasonic method and device for lypolytic therapy

Abstract: The invention relates to an ultrasound transducer for use in therapy or diagnostics. More particularly, it can be used successfully in lypolytic therapy. Said ultrasound transducer comprises different segments, which allows changing curvature radius and consequently focal distance. In this case, depth and volume in treating adipose tissue (lypolytic therapy) is controllable, which means tissue can be treated selectively. Use of the liquid bag between transducer and skin surface allows propagation of ultrasound waves to the target area. After identifying fatty tissue or lypolytic depth, ultrasound transducer must be adjusted for needed focal distance and deliver ultrasound energy for treatment.

Piezoelectric electroacoustic transducer

Abstract: A piezoelectric electroacoustic transducer eliminates the need for the interconnection between main surface electrodes and internal electrodes, and is capable of constructing a bimorph diaphragm using a simple connection structure. The piezoelectric electroacoustic transducer includes a laminated body formed by laminating two or three piezoelectric ceramic layers, main surface electrodes each provided on the top and bottom main surfaces, and an internal electrode provided between any adjacent two piezoelectric ceramic layers. In the piezoelectric electroacoustic transducer, all ceramic layers are polarized in the same direction with respect to the thickness direction, and by applying an alternating voltage across the main surface electrodes and the internal electrode, the laminated body generates a bending vibration in its entirety.

Method and apparatus for ultrasonic imaging

Abstract: An ultrasound transducer array (408) includes at least one transducer element (412) having a first (604) and second (606) portions separated by an acoustical discontinuity (520). The first portion (604) has the desired length to form a half-wave k31 resonance, while the second portion (606) has a resonant length for an undesired very low frequency out-of-band k31 resonance. The thickness of the transducer element (412) is designed for k33 half-resonance. Given the design, the transducer element (412) can operate and provide for both forward-looking (514) and side looking (512) elevation apertures. A method is also disclosed for using the disclosed ultrasound transducer (412) in ultrasound imaging.