78 results about "Impedance sensing" patented technology

An impedance monitoring circuit for an electrosurgical generator is disclosed. The monitoring circuit includes an isolation transformer coupled to at least one of an active terminal and a return terminal of an electrosurgical generator, wherein the isolation transformer includes a primary winding coupled to a reference resistor and a secondary winding coupled to a load. The monitoring circuit also includes a driver configured to transmit a sensor signal to the reference resistor and the load, a primary converter coupled to the reference resistor and the load and configured to detect a primary converted signal as a function of the sensor signal passing through the reference resistor and the load. The monitoring circuit further includes a secondary converter coupled to the driver and configured to detect a secondary converted signal as a function of the sensor signal prior to passing through the reference resistor and the load and a controller configured to determine a fault condition based on the primary and secondary converted signals.

A near field RF communicator (100) has an inductive coupler (102) and a first signal provider (109, 110, 111) to cause the inductive coupler to provide a first signal that when inductively coupled to the inductive coupler of another near field RF communicator in near field range is insufficient to cause initiation of communication with that other near field RF communicator. A sensor (116) senses a change in an impedance of the inductive coupler (102) due to inductive coupling of the first signal between the inductive couplers of the said near field RF communicator and a said other near field RF communicator in near field range. A controller (107) determines whether or not another near field RF communicator is in near field range on the basis of any change in impedance sensed by the sensor and, if another near field RF communicator is determined to be in near field range, causes a second signal to be inductively coupled to the other near field RF communicator to initiate communication between the two near field RF communicators. The sensor may use a phase detector (118) to enable a change in impedance to be sensed by detecting a change in a current-voltage phase relationship resulting from a change in impedance.

The invention is directed to a multi-electrode ablation sensing catheter and system suitable for medical procedures such as cardiac ablation. In one embodiment of the invention, a catheter is provided having an elongated catheter shaft and a catheter tip having two or more closely spaced electrodes mounted on the catheter tip, where the electrodes are coupled to a plurality of electronic circuitries and are used for electrogram sensing, impedance sensing, and location sensing and orientation. In another embodiment of the invention, a catheter system is provided having a catheter with an elongated catheter shaft and a catheter tip with two or more closely spaced electrodes mounted on the catheter tip, and an RF generator circuitry, an electrogram sensing circuitry, an impedance sensing circuitry, and a location sensing and orientation circuitry.

The present invention provides a method and apparatus for assessing ventricular function on a chronic basis using a plurality of electrodes disposed on or about a left ventricle and / or a right ventricle—and optionally, at least one mechanical or metabolic sensor—all operatively electrically coupled to an implantable medical device. The plurality of electrodes are preferably spaced-apart so that at least one electrode is disposed electrical communication with a discrete volume of ventricular tissue. In one embodiment, the discrete volume of tissue is defined by multiple longitudinal and axial planes as known and used in the medical arts. Thus, according to the present invention, at least one electrode couples to appropriate sensing circuitry and essentially provides a localized electrogram (EGM) that, when compared to other EGMs, provides for configurable, localized delivery of therapeutic pacing stimulus, diverse impedance-sensing vectors, various diagnostic information regarding myocardial function and / or anti-tachycardia pacing.

The present invention relates to methods and devices for formation of microconduits in tissue, particularly using an impedance sensing drill to form microconduits. One embodiment of the invention is an impedance sensing drill comprising a drilling assembly, a control module, mechanically connected to the drilling assembly for controlling the depth of drilling by the drilling assembly; and a sensor, electrically connected to the drilling assembly and control module for detecting a change in an electrical impedance of a material being drilled. Another embodiment is a method of forming a microconduit in a material, which comprises the steps of drilling into the material, monitoring an electrical impedance of the material, and stopping the drilling into the material when a change in the impedance is detected, thereby forming microconduit.

The present invention provides a method and apparatus for assessing ventricular function on a chronic basis using a plurality of electrodes disposed on or about a left ventricle and / or a right ventricle—and optionally, at least one mechanical or metabolic sensor—all operatively electrically coupled to an implantable medical device. The plurality of electrodes are preferably spaced-apart so that at least one electrode is disposed electrical communication with a discrete volume of ventricular tissue. In one embodiment, the discrete volume of tissue is defined by multiple longitudinal and axial planes as known and used in the medical arts. Thus, according to the present invention, at least one electrode couples to appropriate sensing circuitry and essentially provides a localized electrogram (EGM) that, when compared to other EGMs, provides for configurable, localized delivery of therapeutic pacing stimulus, diverse impedance-sensing vectors, various diagnostic information regarding myocardial function and / or anti-tachycardia pacing.

An apical foramen locator that a dental or medical practitioner can use to quickly and accurately identify the location of a patient's apical foramen during a dental / medical procedure is provided. The apical foramen locator determines the location of the apical foramen relative to a tool inserted into the patient's tooth by sensing an impedance—typically the voltage across two electrodes—and a stimulus voltage, and retrieving from an impedance map apical foramen location data that corresponds to the sensed impedance. The apical foramen locator can include a power circuit operable to apply a stimulus voltage across two electrodes and a reference resistor, an impedance-sensing circuit operable to read the stimulus voltage, a first voltage across the electrodes and a second voltage across the reference resistor and a processing component operable to derive first and second voltage indices from the stimulus, first and second voltages. Impedance maps can be generated using the apical foramen locator on reference teeth and can be stored in a memory used by the processing component.

Speakers (e.g. “loudspeakers”) from different manufactures may have differing characteristics. In order to improve audio performance, an audio system may customize audio settings based on characteristics of an attached speaker. Described is a technique for determining speaker characteristics by sending a signal through a filter of the attached speaker. The signal may be a probing signal that produces no audible effect from the speaker. The signal may progress through one or more frequency ranges and an impedance signature may be measured. When the signal progresses through a frequency range, the impedance may be measured and a speaker model type and / or characteristics or condition of the speaker may be determined based on the measured impedance.

An impedance monitoring circuit for an electrosurgical generator is disclosed. The monitoring circuit includes an isolation transformer coupled to at least one of an active terminal and a return terminal of an electrosurgical generator, wherein the isolation transformer includes a primary winding coupled to a reference resistor and a secondary winding coupled to a load. The monitoring circuit also includes a driver configured to transmit a sensor signal to the reference resistor and the load, a primary converter coupled to the reference resistor and the load and configured to detect a primary converted signal as a function of the sensor signal passing through the reference resistor and the load. The monitoring circuit further includes a secondary converter coupled to the driver and configured to detect a secondary converted signal as a function of the sensor signal prior to passing through the reference resistor and the load and a controller configured to determine a fault condition based on the primary and secondary converted signals.

Apparatus and method for controlling the frequency of the current in the excitation coil of a handpiece of a dental magnetostrictive ultrasonic scaling unit, or a similar transducer. A microprocessor continually samples predetermined functions of the current through the excitation coil, and periodically adjusts the frequency, by performing a coarse-stepped frequency scan, followed by a fine-stepped frequency scan until the function samples are close to predetermined optimum values. The functions can include the peak of the current and the peak of a high-pass filtered version of the current. The frequency adjustment is performed each time the handpiece is energized by the practitioner, and at frequent intervals thereafter, assuring automatic optimal frequency at all times and under all conditions. Apparatus according to the invention does not require sensing coils or complex power- or impedance-sensing circuitry and covers a wide range of resonant frequencies for different handpiece- and insert types. A configuration with multiple handpieces is supported.

Apparatus and method for controlling the frequency of the current in the excitation coil of the handpiece of a dental magnetostrictive ultrasonic scaling unit, or similar transducer. A microprocessor continually samples a predetermined function of the current through the excitation coil, and adjusts the frequency for a function maximum, performing coarse and fine frequency adjustments. The function can be proportional to the current, its time-derivative, or combination thereof A voltage-controlled oscillator is employed, controlled by pulse-width modulation from the microprocessor. The base frequency scan is performed each time the handpiece is energized by the practitioner, assuring automatic optimal frequency adjustment at all times and under all conditions. Apparatus according to the invention does not require transformers, sensing coils, or complex power- or impedance-sensing circuitry, and covers a wide range of resonant frequencies for different insert types. A configuration with multiple handpieces is supported.

A blood glucose measuring device is equipped with a drill device, attachment assembly, and disposable sensing and measurement assembly. The attachment assembly contains an attachment ring that connects to the drill device and is used to hold the disposable sensing and measurement assembly. A detach actuating cam and output shaft are attached to the drill device. Spring tongs are attached to the output shaft by a compression ring further clamp to an end cap. A skin penetrator is attached to the end cap. The disposable sensing and measurement assembly is enclosed in a disposable case. An outer telescoping anti-bend tube is attached to the end cap. An inner anti-bend capillary sensor tube contains analyte sensors and is attached to the disposable case. The electrical conductors for the analyte sensor electrodes are attached to the capillary sensor tube and thus to the disposable case. An impedance sensing electrode on the bottom of the case provides electrical contacts to the skin. The electrical conductor to the impedance sensing electrode is attached to the bottom of the disposable case.

Devices and methods for assessing tissue contact based on dielectric properties and / or impedance sensing are disclosed. In some embodiments, one or more probing frequencies are delivered via electrodes including an electrode in proximity to a tissue (for example, myocardial tissue). In some embodiments, dielectric parameter values, optionally together with other known and / or estimated tissue characteristics, are measured to determine a contact quality with the tissue. In some embodiments, dielectric contact quality is used, for example, in guiding the formation of a lesion (for example, RF ablation of heart tissue to alter electrical transmission characteristics).

An audio system includes a CODEC audio jack having left and right audio ports and a jack sense circuit. The jack sense circuit includes left and right amplifiers and a cross-drive impedance sensing circuit. This cross-drive impedance sensing circuit, which is electrically coupled to the left and right audio ports and the left and right amplifiers, detects the resistances of left and right output loads in order to determine characteristics of a device connected to the CODEC audio jack. The cross-drive impedance circuit is configured to measure a resistance of a left output load electrically coupled to the left audio port, in response to a “right” test signal generated by the right amplifier, and is further configured to measure a resistance of a right output load electrically coupled to the right audio port in response to a “left” test signal generated by the left amplifier.

A variable impedance sense (VIS) circuit (600) can detect and store an input offset value inherent in a sensing loop (620 and / or 622). According to a detected input offset polarity, a resulting impedance matching binary code can be adjusted to compensate for error that can be introduced by the input offset. The binary code can also be adjusted to compensate for additional error that can be introduced by dropping a least significant bit (LSB) of the code to reduce noise effects caused by the switching of the LSB.

A control system for an implantable cardiac therapy device, the device defining a plurality of sensing vectors including at least one impedance sensing vector and operating under a set of a plurality of variable operating parameters that define conditions for delivery of therapy and wherein the control system evaluates signal quality from the at least one impedance sensing vector and, if the quality is sufficient to discern valvular events, the control system adjusts the set of operating parameters to dynamically improve cardiac performance, including synchrony with valvular events, and if the quality is insufficient to discern valvular events, but sufficient to discern peaks, the control system adjusts the set of operating parameters to dynamically improve cardiac performance independent of valvular events, and if the quality is insufficient to discern peaks, the control system adjusts the set of operating parameters to induce cardiac performance towards a defined performance goal.

This application relates to methods and apparatus for fiber optic sensing which can provide information about the environment in which the fiber optic is deployed. In particular the application relates to fiber optic based sensing of the mechanical impedance of the environment. The method comprises using an interrogator (201) to interrogate an optical fiber (104) which is coupled to a first element (202; 802) which is responsive to electromagnetic fields. In use a varying electric current (I), which may be an alternating current, is applied so as to induce a varying force (F) on said first element. The optical radiation backscattered from within the optical fiber is analyzed to determine a measurement signal indicative of a variation in the backscattered radiation corresponding with said electric current applied. The first element may be a first conductor (202) and the varying current may be supplied to the first conductor, or to a second conductor (701). Alternatively the first element could be a magnetic element (802). By applying a variable force to the first element, and hence the optical fiber, the characteristics of the environment can be determined.

A resonance type impedance sensor which is a multicoil open-core or air-core inductor, said sensor comprising at least two coils, one coil being an excitation coil connectable to at least one alternating current source with frequency sweep, another coil being a sensing coil connectable to at least one data processing system, wherein upon electrical connection to said current source, said excitation coil propagates an energy to said sensing coil, which generates a probing electromagnetic field, and wherein L, C, R parameters of said sensing coil are capable of providing resonance conditions for measuring of object under test impedance at predetermined frequency.

A process for curing a natural or synthetic rubber compound under a plurality of curing conditions by: (1) obtaining time dependent data streams of dielectric or impedance values from a non-bridged impedance sensing circuit and a capacitor having the rubber compound being cured as a dialectric; (2) determining impedance related measurements from the obtained data streams; (3) determining a predictive curing equation by performing a multiple regression between: (a) reheometric data obtained from a plurality of different rubber compound samples cured in a rheometer at various environmental curing conditions, and (b) corresponding samples cured in a production mold at the same environmental conditions; (4) adjusting the curing equation to obtain cured parts having one or more desired properties; and (5) controlling the mass producing cured parts with a controller that uses the curing equation for predicting a cure time for each part, wherein the predictions are effective over variations in the rubber compound, and in the mold temperature.

According to aspects of the present disclosure, a system for detecting moisture in an absorbent article worn by a wearer may include an impedance sensing element. The impedance sensing element may include electrodes. The system may also include an attachment member for securing the impedance sensing element at a location on an exterior surface of the absorbent article. The electrodes may be positioned so as to be capacitively coupled to an interior region of the absorbent article and to measure an impedance of the absorbent article from the location on the exterior surface of the absorbent article. The system may also include an impedance measurement subsystem for measuring the impedance of the absorbent article, and extracting a real component of the impedance and an imaginary component of the impedance for determining a characteristic of the moisture in the absorbent article.

In a method and an implantable medical device for assessing a degree of pulmonary edema of a patient, at least two specific body patients of the patent are detected and at least one impedance sensing session is initiated to sense trans-thoracic impedance signals from the patient when the patient is in one of the at least two specific positions. Impedance values are obtained from the impedance signals, and a relation between respective impedance values at the at least two positions is determined. This relation is then used as a metric of pulmonary edema to assess the degree of pulmonary edema, and is provided as an output.

A gas sensor control apparatus includes a heater regulating section to control the supply of electricity to a heater included in a gas sensor, an impedance sensing section to sense an impedance of a cell of the gas sensor, and an impedance condition examining section to examine whether the sensed impedance is greater than or equal to a predetermined abnormality judging threshold. The control apparatus further includes a voltage condition examining section to examine whether a maximum effective voltage is applied to the heater, when the impedance is above the predetermined abnormality judging threshold, a duration measuring section to examine whether an application time duration of the maximum effective voltage becomes equal to or longer than a predetermined heater overheat preventing time, and a voltage decreasing section to decrease the heater application voltage to such a lower effective voltage as to hold the temperature of the cell higher than or equal to 500° C. when the application time duration reaches the predetermined heater overheat preventing time.

The invention discloses a composite aircraft icing detector and an icing detection method, and belongs to the technical field of aviation detection. The composite aircraft icing detector comprises a double-electrode complex impedance sensing mechanism, a multispectral optical fiber sensing mechanism and a composite probe outer frame, wherein the double-electrode complex impedance sensing mechanism and the detection end surface of the multispectral optical fiber sensing mechanism form a sensitive surface and are positioned on the inclined end surface; the double-electrode complex impedance sensing mechanism collects complex impedance frequency characteristic data in a to-be-detected environment; the multispectral optical fiber sensing mechanism collects spectral response data in the to-be-detected environment, recognizes an ice layer and a water film on a sensitive surface in combination with complex impedance frequency characteristic data, and meanwhile, monitors the dynamic process of water film freezing and ice layer melting in an ice-water mixed phase state, so that icing detection is achieved. The problem that a single principle type sensor fails in a complex icing environment is effectively avoided, the reliability and accuracy of the aircraft icing detector are greatly improved, and the aircraft icing detector has practical significance in guaranteeing efficient and reliable operation of an aircraft anti-icing and deicing system.

A remote sensing power supply regulator uses high impedance sensing inputs coupled internally to at least one circuit element within an integrated circuit, so as to regulate the voltages produced by the power supply to a level that maintains nominal voltage levels at the internal circuit element within the very large scale integrated circuit. The sense point can be chosen to serve one or a group of on-board load elements that are operationally sensitive to voltage droop and / or ground bounce.

The invention provides a mobile equipment input system and a mobile equipment input method using the input system. The mobile equipment input system comprises an electro-acoustic conversion module, an impedance sensing element, an impedance signal processing unit and a central processing unit, wherein the impedance sensing element is used for sensing the impedance signal change of the electro-acoustic conversion module, the impedance signal processing unit is used for receiving the sensing result of the impedance sensing element and correspondingly generating an input operation signal to the central processing unit, and the central processing unit is used for making a response to the input operation signal and driving mobile equipment to execute input operation application. The input system and the input method provided by the invention have the advantages of convenience in operation, simple structure and large display area.

This disclosure describes a chopper stabilized instrumentation amplifier. The amplifier is configured to achieve stable measurements at low frequency with very low power consumption. The instrumentation amplifier uses a differential architecture and a mixer amplifier to substantially eliminate noise and offset from an output signal produced by the amplifier. Dynamic limitations, i.e., glitching, that result from chopper stabilization at low power are substantially eliminated through a combination of chopping at low impedance nodes within the mixer amplifier and feedback. The signal path of the amplifier operates as a continuous time system, providing minimal aliasing of noise or external signals entering the signal pathway at the chop frequency or its harmonics. The amplifier can be used in a low power system, such as an implantable medical device. The amplifier may be used for physiological signal sensing, impedance sensing, telemetry or other test and measurement applications.