Relative impedance measurement
First Claim
1. A method for position sensing, comprising:
- inserting a probe comprising a probe electrode into a body of a subject;
measuring a first current passing through the body between the probe electrode and a first body-surface electrode coupled to a surface of the body;
measuring a second current passing through the body between the probe electrode and a second body-surface electrode coupled to the surface of the body;
calculating a relation between the first and second currents, the relation being indicative of a value of relative impedance between the probe electrode and each of the body-surface electrodes, and being based on a quotient of the first current and a sum of the first and second currents; and
tracking movement of the probe within the body responsively to the relation.
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Accused Products
Abstract
A method for calibrating impedance includes coupling at least first, second, and third electrodes at respective locations to a surface of a body of a subject. A first current passing through the body between the first and second body-surface electrodes is measured, and a second current passing through the body between the first and third body-surface electrodes is measured. From the first and second currents, a contact factor is derived that is indicative of the impedance between at least one of the body-surface electrodes and the surface of the body. Also described are methods for sensing the position of a probe and for detecting tissue contact based on a relation between currents from the probe to body-surface electrodes.
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Citations
6 Claims
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1. A method for position sensing, comprising:
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inserting a probe comprising a probe electrode into a body of a subject; measuring a first current passing through the body between the probe electrode and a first body-surface electrode coupled to a surface of the body; measuring a second current passing through the body between the probe electrode and a second body-surface electrode coupled to the surface of the body; calculating a relation between the first and second currents, the relation being indicative of a value of relative impedance between the probe electrode and each of the body-surface electrodes, and being based on a quotient of the first current and a sum of the first and second currents; and tracking movement of the probe within the body responsively to the relation. - View Dependent Claims (2, 3)
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4. Apparatus for position sensing, comprising:
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a probe, comprising a probe electrode, adapted to be inserted into a body of a subject; a first body-surface electrode and a second body-surface electrode, each adapted to be coupled at respective locations to a surface of the body; and a control unit, adapted to measure a first current passing through the body between the probe electrode and the first body-surface electrode, to measure a second current passing through the body between the probe electrode and the second body-surface electrode, to calculate a relation between the first and second currents, and to track movement of the probe within the body responsively to the relation, wherein the relation is indicative of a value of relative impedance between the probe electrode and each of the body-surface electrodes, and is based on a quotient of the first current and a sum of the first and second currents. - View Dependent Claims (5, 6)
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Specification