6113 results about "Electrical impedance" patented technology

An electrosurgical system comprises a generator and an instrument including a first electrode, a second electrode, and an insulating spacer separating the first and second electrodes. The generator repeatedly measures a characteristic of the radio frequency output such as the impedance between the first and second electrodes. The generator analyses the impedance measurements, and interrupts the radio frequency signal when the rate of change of the impedance is such as to indicate the onset of a “flare-out”. In this way, the power is reduced before the flare-out leads to permanent damage or failure of the instrument.

A system and method for creating lesions and assessing their completeness or transmurality. Assessment of transmurality of a lesion is accomplished by monitoring the impedance of the tissue to be ablated. Rather than attempting to detect a desired drop or a desired increase impedance, completeness of a lesion is detected in response to the measured impedance remaining at a stable level for a desired period of time, referred to as an impedance plateau. The mechanism for determining transmurality of lesions adjacent individual electrodes or pairs may be used to deactivate individual electrodes or electrode pairs, when the lesions in tissue adjacent these individual electrodes or electrode pairs are complete, to create an essentially uniform lesion along the line of electrodes or electrode pairs, regardless of differences in tissue thickness adjacent the individual electrodes or electrode pairs.

Systems and techniques for monitoring hydration. In one implementation, a method includes measuring an electrical impedance of a region of a subject to generate an impedance measurement result, and wirelessly transmitting the data to a remote apparatus. The probe with which impedance is measured may in the form of a patch adhesively secured to the subject.

A method includes providing a source resonator including a first conductive loop in parallel with a first capacitive element and in series with a first adjustable element the source resonator having a source target impedance, providing a plurality of device resonators each including a conductive loop and having a device target impedance, connecting, for each of the plurality of device resonators, a resistor corresponding to the device target impedance in series with the conductive loop of each of the plurality of device resonators, connecting a network analyzer in series with the first conductive loop and adjusting at least one of the first capacitive element and the first adjustable element until a measured impedance of the source resonator is within a predetermined range of the source target impedance.

An electrical current is created across an electrically conductive medium comprising a cell which may be part of a tissue of a living organism. A first electrical parameter which may be current, voltage, or electrical impedance is measured. A second electrical parameter which may be current, voltage or a combination of both is then adjusted and/or analyzed. Adjustments are carried out to facilitate analysis and/or obtain a desired degree of electroporation. Analysis is carried out to determine characteristics of the cell membrane and/or tissue.

A communications apparatus comprising a first antenna, a first serial configuration of a first power amplifier and a first matching network, a second serial configuration of a second power amplifier and a second matching network, a switching element for switchably selecting the first or the second serial configuration for supplying a signal to the first antenna, the first and the second power amplifiers supplying a respective first signal of a first power and a second signal of a second power different than the first power to the first antenna for transmitting and the first and the second matching networks presenting respective first and second impedances to the respective first and second power amplifiers, the first and the second impedances responsive respectively to a power-related parameter of the first and the second signals.

A system for creating lesions and assessing their completeness or transmurality. Assessment of transmurality of a lesion is accomplished by monitoring the impedance of the tissue to be ablated. Rather than attempting to detect a desired drop or a desired increase impedance, completeness of a lesion is detected in response to the measured impedance remaining at a stable level for a desired period of time, referred to as an impedance plateau. The mechanism for determining transmurality of lesions adjacent individual electrodes or pairs may be used to deactivate individual electrodes or electrode pairs, when the lesions in tissue adjacent these individual electrodes or electrode pairs are complete, to create an essentially uniform lesion along the line of electrodes or electrode pairs, regardless of differences in tissue thickness adjacent the individual electrodes or electrode pairs.

An elongated, flexible, flat conductive tape can be applied to any surface to be monitored for water or other liquid leaks, and electrically connected to any suitable type of conventional electrically operated leak detector. A pair of parallel spaced conductors is disposed on one side of the tape that run longitudinally along the length thereof. The conductors are spaced from one another by a small distance to insure that only a small quantity of water or other conductive liquid is necessary to bridge the gap between the conductors, and create an electrical short circuit or substantial impedance reduction between the two. In addition, the conductors are preferably as flat as possible to insure that liquid can freely flow transversely across them without being impeded thereby. Both of these features insure that the detector tape can sense even very small quantities of liquid, thereby generating an early warning of a leak condition before extensive damage results. A liquid responsive visible indication is also provided on the tape to identify the location along the tape where water or other leaking liquid has come in contact therewith, and eliminates the need for using an expensive sensing device to locate the source of a leak.

A reflective impedance element is connected to a port of a composite right/left-handed transmission line, and operates at a predetermined operating frequency so that an impedance when the reflective impedance element is seen from the port becomes a pure imaginary number jB. A reflective impedance component is connected to a port of the composite right/left-handed transmission line, and operates at the predetermined operating frequency so that an impedance when the reflective impedance element is seen from the port becomes −jB.

An electrical impedance probe is provided that includes a surgical needle. In an exemplary embodiment, the probe is a two-part trocar needle designed to acquire impedance measurements at its tip. The impedance measurements are representative of the local properties of a biological substance at the needle tip. Thus, the probe may be used to confirm needle insertion into a desired anatomical target or to identify the nature of the cells surrounding the tip of the needle. In urology, this sensor is used for confirming the needle insertion into the urinary tract, for localizing renal cell carcinoma, and prostate cancer.

Control system for devices such as an audio reproduction system, an actuator device, an electromechanical device and a telephony device. The system includes control circuitry which receives an input signal and a signal indicative of a position of a portion of the controlled apparatus. The control circuit provides an output signal to the controlled apparatus to affect an operation of the controlled apparatus. The output signal provides control of the apparatus to compensate for one or more of: motor factor; spring factor; back electromotive force; and impedance of a coil in a driver of the controlled apparatus. The signal indicative of position is derived by one or more position indicator techniques such as an infrared LED and PIN diode combination, position dependent capacitance of one portion of the controlled apparatus with respect to another portion of the controlled apparatus, and impedance of a coil in the controlled apparatus. The control circuitry is configurable to control transconductance and/or transduction of the system being controlled. A technique is disclosed to detect and measure a cant of a voice coil transducer, the technique including measuring a capacitance between one portion of the voice coil transducer with respect to another portion of the voice coil transducer over a range of movement of the voice coil during operation.

A system and method for heat ablation of tissue in which energy is sequentially applied to at least two electrodes inserted into tissue. The system is comprised of a radiofrequency (RF) source for supplying RF energy, at least two electrodes configured to apply RF energy to tissue, at least one return electrode for returning the RF energy to the RF source, and a controller configured to sequentially apply the RF energy to each of the at least two electrodes. The sequential delivery of energy is determined by the measured current and voltage, the calculated impedance at each of the electrodes and the timing for each electrode. An internal load may be activated with the previously activated channel and remain on until the next channel is activated to avoid the generator from having an open circuit.