APPARATUS AND METHOD FOR SENSING FORCE ON A ROBOTICALLY CONTROLLED MEDICAL INSTRUMENT

• US 20100121269A1
• Filed: 12/17/2009
• Published: 05/13/2010
• Est. Priority Date: 11/12/2008
• Status: Active Grant

• Current Assignee: Auris Health, Inc. (Johnson & Johnson)
• Original Assignee: Hansen Medical Incorporated (Johnson & Johnson)
• Inventors: Schultheis, Eric A., Goldenberg, Alex, Schlesinger, Randall L.
• Granted Patent: US 8,372,019 B2
• Time in Patent Office: Days
• US Class Current: 604/95.10
• CPC Class Codes: A61B 1/005 Flexible endoscopes
• CPC Class Codes: A61B 10/06 Biopsy forceps , e.g. with cup-shaped jaws
• CPC Class Codes: A61B 17/29 Forceps for use in minimally invasive surgery
• CPC Class Codes: A61B 18/1492 having a flexible, catheter-like structure, e.g. for heart ablation A61B18/1477 takes precedence
• CPC Class Codes: A61B 2017/00477 Coupling A61B2017/0046 takes precedence
• CPC Class Codes: A61B 2017/2902 characterized by features of the actuating rod
• CPC Class Codes: A61B 2018/00273 Anchoring means for temporary attachment of a device to tissue
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00791 Temperature
• CPC Class Codes: A61B 2018/00815 measured by a thermistor
• CPC Class Codes: A61B 2018/00839 Bioelectrical parameters, e.g. ECG, EEG
• CPC Class Codes: A61B 2034/301 for introducing or steering flexible instruments inserted into the body, e.g. catheters or endoscopes
• CPC Class Codes: A61B 2090/064 for measuring force, pressure or mechanical tension
• CPC Class Codes: A61B 2090/065 for measuring contact or contact pressure
• CPC Class Codes: A61B 2218/002 Irrigation
• CPC Class Codes: A61B 5/01 Measuring temperature of body parts ; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue clinical contact thermometers G01K13/20
• CPC Class Codes: A61B 5/24 Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
• CPC Class Codes: A61B 5/6885 Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61M 25/0105 Steering means as part of the catheter or advancing means; Markers for positioning systems for detection of markers A61B

Abstract

A medical system comprises a medical probe including an elongated probe body, a lumen extending within the probe body, an axially flexible section, and a push-pull member slidably disposed within the lumen. The system comprises a ditherer mechanically coupled to the member for cyclically displacing it axially back and forth within the lumen, such that the ends of the probe body are axially displaced relative to each other via the axially flexible section. The system further comprises a sensor for sensing a force axially applied to the distal end of the probe body. A method comprises introducing a medical probe into a patient, axially dithering the distal end of the medical probe back and forth relative to the proximal end of the medical probe, and sensing a force applied between tissue of the patient and the distal end of the medical probe while the distal end is axially dithered.

Claims

1. A medical instrument system, comprising:

an elongated probe body having a bendable section, a distal tip section, and an axially variable-length section disposed between the bendable and distal tip sections, the probe body having a lumen axially extending therethrough;

a push-pull member slidably disposed in the lumen of the probe body, the push-pull member having a distal end affixed to the distal tip section of the probe body and a proximal end portion extending out a proximal end of the probe body;

a dithering mechanism configured to mechanically couple to the proximal end portion of the push-pull member, the dithering mechanism further configured for cyclically displacing the push-pull member axially back and forth within the lumen of the probe body, such that the distal tip section is axially displaced relative to bendable section via the axially variable-length section;

at least one force sensor positioned adjacent to the proximal end portion of the push-pull member, the at least one force sensor being configured for measuring a load applied to the push-pull member; and

a processor operatively coupled to the at least one force sensor and configured for determining an external force axially applied to the distal tip section of the probe body based on signals received from the at least one force sensor.

2. The medical instrument system of claim 1, wherein the probe body comprises a flexible intravascular catheter body having an operative element mounted on the distal tip section.

3. The medical instrument system of claim 1, wherein the axially variable-length section of the probe body comprises an axially compressible polymer sleeve.

4. The medical instrument system of claim 1, wherein the axially variable-length section of the probe body comprises a bellows.

5. The medical instrument system of claim 1, wherein the axially variable-length section of the probe body comprises a spring, the spring having a distal end coupled to the distal tip section and a proximal end coupled to the bendable section.

6. The medical instrument system of claim 1, the medical probe further comprising a stiffening coil extending axially therethrough, wherein the push-pull member extends through a central lumen of the stiffening coil.

7. The medical instrument system of claim 6, wherein the stiffening coil is affixed to the probe body at a steering wire anchor member located at a distal end of the bendable section.

8. The medical instrument system of claim 6, the bendable section of the probe body terminating distally at a steering wire anchor, the stiffening coil extending distally past the steering wire anchor and through the axially variable-length section to the distal tip section of the probe body, wherein a pitch of portion of the stiffening coil passing through the axially variable-length section being significantly opened up compared with a pitch of the more proximal portion of the stiffening coil so that the portion of the stiffening coil passing through the axially variable-length section of the probe body acts as a spring to maintain the push-pull member in tension as the push-pull member is dithered back and forth through the probe body lumen.

9. The medical instrument system of claim 1, wherein the force sensor is mounted on the dithering mechanism.

10. The medical instrument system of claim 1, wherein the push-pull member comprises a fluid delivery tube having an open distal end coupled to the distal tip section.

11. The medical instrument system of claim 1, wherein the medical probe further includes at least one control element extending within the probe body, and wherein the system is robotically controlled instrument system including an instrument driver having an adapter configured to be operatively coupled to the at least one control element for bending the bendable section of the probe body in at least one direction.

12. The medical instrument system of claim 11, wherein the at least one control element comprises a plurality of steering wires affixed to the probe body at a steering wire anchor member located at a distal end of the bendable section.

13. The medical instrument system of claim 11, wherein the dithering mechanism is mounted on the instrument driver.

14. The medical instrument system of claim 1, wherein the probe body is manually controlled using a handle attached to a proximal end of the probe body, and wherein the dithering mechanism is located on or in the handle.

15. The medical instrument system of claim 1, wherein the processor determines the external force axially applied to the distal tip section of the probe by:

obtaining a baseline force measurement from the at least one force sensor when the push-pull member is dithered back and forth without any external axial force being applied to the distal tip section of the probe body,

obtaining a total force measurement from the at least one force sensor when the push-pull member is dithered back and forth with an external axial force applied to the distal tip section of the probe body, and

computing the external axial force applied to the distal tip section of the probe body by subtracting the baseline force measurement from the total force measurement.

16. A medical instrument system, comprising:

a medical probe including an elongated probe body having a bendable section, a distal tip section, and an axially translatable section disposed between the bendable and distal tip sections, the axially translatable section comprising at least one seal that allows one of the bendable and distal tip sections to slide within the other one of the bendable and distal tip sections, the probe further including an axially extending inner lumen;

a push-pull member slidably disposed in the lumen of the probe body, the push-pull member having a distal end affixed to the distal tip section of the probe body and a proximal end portion extending out a proximal end of the probe body;

a dithering mechanism configured to mechanically couple to the proximal end portion of the push-pull member, the dithering mechanism further configured for cyclically displacing the push-pull member axially back and forth within the lumen of the probe body, such that the distal tip section is axially displaced relative to bendable section via the axially translatable section;

at least one force sensor positioned adjacent the proximal end portion of the push-pull member, the at least one force sensor being configured for measuring a load applied to the push-pull member; and

a processor operatively coupled to the at least one force sensor and configured for determining an external force axially applied to the distal tip section of the probe body based on signals received from the at least one force sensor.

17. The medical instrument system of claim 16, wherein the processor determines the external force axially applied to the distal tip section of the probe by:

obtaining a baseline force measurement from the at least one force sensor when the push-pull member is dithered back and forth without any external axial force being applied to the distal tip section of the probe body,

obtaining a total force measurement from the at least one force sensor when the push-pull member is dithered back and forth with an external axial force applied to the distal tip section of the probe body, and

computing the external axial force applied to the distal tip section of the probe body by subtracting the baseline force measurement from the total force measurement.

18. A medical method, comprising:

introducing a medical probe into a patient, the medical probe having an elongated probe body;

axially dithering a distal end portion of the probe body back and forth relative to a more proximal portion of the probe body; and

determining a force applied between internal body tissue of the patient and the distal end of the probe body while the distal end of the probe body is axially dithered.

19. The medical method of claim 18, wherein the distal end portion of the probe body is axially dithered relative to the more proximal portion using a push-pull member extending axially through a central lumen of the probe body, the push-pull member having a distal end attached to the distal end portion of the probe body, the probe body further comprising an axially variable-length portion interposed between the respective distal end and more proximal portions of the probe body.

20. The medical method of claim 19, wherein the push-pull member comprises a fluid delivery tube having an open distal end coupled to the distal end portion of the probe body.

21. The medical method of claim 19, wherein the axially variable-length portion of the probe body comprises a spring.

22. The medical method of claim 19, wherein the probe body is robotically controlled by an instrument driver having an adapter configured to be operatively coupled to one or more steering wires extending through the probe body for controllable bending a bendable portion of the probe body in at least one direction, the one or more steering wires having distal ends affixed to the probe body at a steering wire anchor member located at a distal end of the bendable portion, the push-pull member extending distally past the anchor member to the distal end portion of the probe body.

23. The medical method of claim 18, wherein the force applied between the internal body tissue of the patient and the distal end of the probe body is determined by

obtaining a baseline force measurement when the distal end of the probe body is axially dithered back and forth without any external axial force axially applied between the body tissue and the distal end of the probe body, and

obtaining a total force measurement when the distal end of the probe body is dithered back and forth with the external axial force axially applied between the tissue and the distal end of the probe body, and subtracting the baseline force measurement from the total force measurement.

24. A medical instrument system, comprising:

an elongated probe body having a bendable section, a distal tip section, and an axially variable-length section disposed between the bendable and distal tip sections;

a push-pull member slidably disposed in an axially extending lumen of the probe body, the push-pull member having a distal end affixed to the distal tip section of the probe body and a proximal end portion extending out a proximal end of the probe body;

a dithering mechanism configured for attaching to the proximal end portion of the push-pull member, the dithering mechanism further configured for cyclically displacing the push-pull member axially back and forth within the lumen of the probe body, such that the distal tip section of the probe body is axially displaced relative to bendable section of the probe body via the axially variable-length section of the probe body;

a force sensor positioned adjacent to the proximal end portion of the push-pull member, the force sensor being fixed relative to the push-pull member and configured for measuring a load applied to the push-pull member.

25. The medical instrument system of claim 24, wherein the axially variable-length section of the probe body comprises an axially compressible polymer sleeve and a spring carried in a lumen of the sleeve, the spring having a distal end coupled to the distal tip section of the probe body, and a proximal end coupled to the bendable section of the probe body, such that the spring is cyclically compressed and decompressed as the distal tip section is axially dithered back and forth relative to the bendable section, the push-pull member extending through a lumen of the spring.

26. The medical instrument system of claim 24, further comprising a stiffening coil extending axially through the lumen of the probe body, the push-pull member extending through a central lumen of the stiffening coil.

27. The medical instrument system of claim 26, wherein the stiffening coil is affixed to the probe body at a steering wire anchor member located at a distal end of the bendable section.

28. The medical instrument system of claim 26, the bendable section of the probe body terminating distally at a steering wire anchor, the stiffening coil extending distally past the steering wire anchor and through the axially variable-length section to the distal tip section of the probe body, wherein a pitch of portion of the stiffening coil passing through the axially variable-length section being significantly opened up compared with a pitch of the more proximal portion of the stiffening coil so that the portion of the stiffening coil passing through the axially variable-length section of the probe body acts as a spring to maintain the push-pull member in tension as the push-pull member is dithered back and forth through the probe body lumen.

29. The medical instrument system of claim 24, wherein the force sensor is mounted on the dithering mechanism.

30. The medical instrument system of claim 24, wherein the push-pull member comprises a fluid delivery tube.

31. The medical instrument system of claim 30, further comprising a stiffening coil extending axially through the lumen of the probe body, the fluid delivery tube extending through a central lumen of the stiffening coil.

32. The medical instrument system of claim 31, wherein the stiffening coil is affixed to the probe body at a steering wire anchor member located at a distal end of the bendable section.

33. The medical instrument system of claim 31, the bendable section of the probe body terminating distally at a steering wire anchor, the stiffening coil extending distally past the steering wire anchor and through the axially variable-length section to the distal tip section of the probe body, wherein a pitch of portion of the stiffening coil passing through the axially variable-length section being significantly opened up compared with a pitch of the more proximal portion of the stiffening coil so that the portion of the stiffening coil passing through the axially variable-length section of the probe body acts as a spring to maintain the fluid delivery tube in tension as the tube is dithered back and forth in the probe body lumen.

34. The medical instrument system of claim 24, wherein the system is robotically controlled instrument system including an instrument driver having an adapter configured to be operatively coupled to one or more steering wires extending through the bendable section of the probe body, the one or more steering wires each having a distal end affixed to a steering wire anchor member located at a distal end of the bendable section, the push-pull member extending past the steering wire anchor and through a lumen of the axially variable-length section to the distal tip section.

35. The medical instrument system of claim 34, wherein the dithering mechanism is mounted on the instrument driver.

36. The medical instrument system of claim 24, wherein the probe body is manually controlled using a handle attached to a proximal end of the probe body, and wherein the dithering mechanism is located on or in the handle.

37. The medical instrument system of claim 24, further comprising a processor operatively coupled to the force sensor and configured for determining an external force axially applied to the distal tip section of the probe body by

obtaining a baseline force measurement from the at least one force sensor when the push-pull member is dithered back and forth without any external axial force being applied to the distal tip section of the probe body,

obtaining a total force measurement from the at least one force sensor when the push-pull member is dithered back and forth with an external axial force applied to the distal tip section of the probe body, and

computing the external axial force applied to the distal tip section of the probe body by subtracting the baseline force measurement from the total force measurement.