Symmetric short contact force sensor with four coils

Patent metadata

Field	Value
Publication number	US-10383543-B2
Application number	US-201514937998-A
Country	US
Kind code	B2
Filing date	Nov 11, 2015
Priority date	Nov 11, 2015
Publication date	Aug 20, 2019
Grant date	Aug 20, 2019

Abstract

In a flexible catheterization probe a resilient member couples the tip to the distal portion of the probe and is configured to deform in response to pressure exerted on the tip when engaging tissue. A position sensor in the distal portion of the probe senses the position of the tip relative to the distal portion of the probe. The relative position changes in response to deformation of the resilient member. The position sensor generates a signal indicative of the position of the tip responsively to a magnetic field produced by a magnetic field generator located in the position sensor. The position sensor has a first coil of conductive wire having first windings, and three second coils of conductive wire having respective second windings. The second coils are symmetrically distributed about the longitudinal axis of the first coil.

First claim

The invention claimed is:

1. A method, comprising the steps of:
inserting a flexible probe into a body cavity of a patient, the flexible probe having a distal portion and a distal tip coupled to the distal portion by a resilient member, the resilient member being configured to deform in response to pressure exerted on the distal tip when the distal tip engages tissue within the body cavity, a magnetic field generator located within the distal tip for generating a magnetic field and a position sensor disposed in the distal portion, the position sensor comprising a first coil of conductive wire having a longitudinal axis and first windings and three second coils of conductive wire having respective second windings, the second coils being symmetrically distributed about the longitudinal axis of the first coil;
bringing the distal tip of the probe into contact with the tissue in the body cavity;
sensing a position of the distal tip relative to the distal portion of the probe with the position sensor, wherein the position of the distal tip changes in response to deformation of the resilient member,
generating a signal indicative of the position of the distal tip responsively to a magnetic field that is generated in a vicinity of the distal tip, wherein generating the signal comprises determining a first force vector using signals from the first coil and the three second coils;
determining a second force vector using signals only from the three second coils;
determining a third force vector using signals only from the first coil;
when the second force vector and the third force vector differ by less than a threshold using the first force vector as the signal indicative of the position of the distal tip; and
when the second force vector and the third force vector differ by more than the threshold using the third force vector as the signal indicative of the position of the distal tip.

2. The method according to claim 1 , in which there are exactly three second coils.

3. The method according to claim 1 , wherein the first windings are directed about the longitudinal axis of the first coil.

4. The method according to claim 1 , wherein the second coils are elliptical coils having major axes, a first vertex and a second vertex, respectively.

5. The method according to claim 4 , wherein the second coils are in contact with the first coil.

6. The method according to claim 4 , wherein the major axes of the elliptical coils are parallel to the longitudinal axis of the first coil.

7. The method according to claim 4 , wherein the second windings are directed from the first vertex to the second vertex, respectively.

8. The method according to claim 1 , wherein the first coil is wound about a hollow tube.

9. The method according to claim 1 , wherein the second coils are air core inductors.

Assignees

• Biosense Webster Israel Ltd

Inventors

• Bonyak Yevgeny
• Levy Dror Shlomo
• Ludwin Doron Moshe
• Saba Eitan Moshe
• Bar-Tal Meir

Classifications

• A61B2090/065

  for measuring contact or contact pressure · CPC title

• A61B2018/00357

  Endocardium · CPC title

• A61B5/6885

  Monitoring or controlling sensor contact pressure · CPC title

• A61B2018/00839

  Bioelectrical parameters, e.g. ECG, EEG · CPC title

• A61B2034/2051

  Electromagnetic tracking systems · CPC title