Coils formed from folded Nitinol sheets

Abstract

To provide a catheter having a contact force sensor.SOLUTION: A contact force sensor is constructed using a spring in which a resilient member is interposed between two contacting elements. Extensions connected to the resilient member are in contact with the elements. A force applied to at least one of the elements causes a deformation of the spring that correlates with a displacement of the elements relative to one another.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] (Copyright information) A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by any of the patent document or patent disclosure as disclosed in the Patent and Trademark Office patent application or records, but otherwise reserves all copyright rights whatsoever.

[0002] FIELD OF THEINVENTION The present invention relates to hollow probes and catheters, and more particularly to catheters having contact force sensors. [Background technology]

[0003] Cardiac arrhythmias, such as atrial fibrillation, occur when areas of cardiac tissue disrupt the normal cardiac cycle by abnormally conducting electrical signals to adjacent tissue, causing an asynchronous rhythm.

[0004] Procedures for treating arrhythmias include surgically destroying the source of the signals that are causing the arrhythmia and destroying the conduction pathways of such signals. By selectively ablating cardiac tissue with energy applied via a catheter, it is sometimes possible to stop or redirect the propagation of undesired electrical signals from one part of the heart to another. Ablation techniques destroy undesired electrical pathways by creating non-conducting lesions.

[0005] Demonstrating physical electrode contact with the target tissue is important to control the delivery of ablation energy. In the art, attempts to demonstrate tissue-electrode contact have been extensive, and various techniques have been proposed. For example, U.S. Patent No. 6,695,808 describes an apparatus for treating a selected patient tissue or organ region. A probe has a contact surface that can be pressed against the region, thereby creating a contact pressure. A pressure transducer measures the contact pressure. This configuration is said to meet the treatment requirement that the medical device must be firmly positioned, but not excessively contacting, the anatomical surface, by providing the device user with information indicative of the presence and magnitude of the contact force.

[0006] Commonly assigned U.S. patent application Ser. No. 14 / 937,998 to Bonyak et al., which is incorporated herein by reference, describes a symmetric contact force sensor in a probe. A resilient member couples the tip to a distal portion of the probe and is configured to deform in response to pressure applied to 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 in response to a magnetic field generated by a magnetic field generator located in the position sensor. Summary of the Invention [Means for solving the problem]

[0007] Springs found in conventional contact force sensors are individually prepared, for example, by cutting from Nitinol tubing material. Embodiments of the present invention provide a catheter having a contact force sensor and method of manufacturing the catheter using a spring design that is cut from a flat sheet of metal and shape set into its final form. The design is adaptable for mass production and can be fitted into small spaces such as those required for contact force sensors in medical catheters.

[0008] According to an embodiment of the present invention, a device is provided in which a spring has a resilient member inserted between two contacting elements, an extension connected to the resilient member is in contact with the elements, and a force applied to at least one of the elements produces a deformation of the spring that correlates with the displacement of the elements relative to each other.

[0009] According to one aspect of the device, the resilient member includes a central ring with a first segment of the ring disposed on one side of a plane and a second segment disposed on another side of the plane, and the deformation includes bringing the first segment and the second segment closer to the plane.

[0010] According to another aspect of the device, the resilient member includes a central ring having a sinusoidal configuration with radial vibrations toward and away from its central point.

[0011] According to one aspect of the device, the resilient member includes a central ring including a plurality of sectors, each of the sectors being shaped into two hairpin curves.

[0012] According to a further aspect of the device, the deformation includes twisting of at least one of the elements relative to another one of the elements.

[0013] According to a further aspect of the device, the extension portion comprises a plurality of legs attached to the central ring, with first and second legs extending in opposite first and second perpendicular directions, respectively, relative to the ring.

[0014] In yet another aspect of the device, the first link and the second link connect the first leg and the second leg, respectively, to the ring at opposite angles relative to the plane, and the deformation includes a decrease in the angle.

[0015] According to yet another aspect of the device, the first leg and the second leg contact an end surface of the respective element.

[0016] According to a further aspect of the device, the first leg and the second leg embrace the respective element.

[0017] There is further provided in accordance with an embodiment of the present invention an apparatus including a flexible insertion tube having a proximal portion and a distal portion for insertion into a body cavity of a patient, and a resilient member coupling the proximal portion of the insertion tube to the distal portion, the resilient member being molded from a shape-set elastic material and having proximal and distal extensions in contact with the proximal and distal portions, respectively, of the insertion tube, and a force applied through the distal portion causes a deformation of the resilient member that correlates with a displacement of the proximal portion relative to the distal portion.

[0018] There is further provided in accordance with an embodiment of the present invention a method of manufacturing a medical probe, the method being performed by providing an elongate probe having a proximal portion and a distal portion, the distal portion having an electrode disposed thereon. The method is further performed by forming a resilient member from sheet metal, the resilient member having an elastic portion and an attachment portion, the attachment portion configured to engage the proximal and distal portions of the probe. The method is further performed by shape-fixing the resilient member and configuring the resilient member as a contact force sensor by coupling the resilient member to the proximal and distal portions such that a force applied through the distal portion causes a deformation of the resilient member that correlates with a displacement of the proximal portion relative to the distal portion.

[0019] According to one aspect of the method, forming the resilient member includes cutting a spring form from sheet metal.

[0020] According to yet another aspect of the method, the cutting is performed by laser cutting.

[0021] According to a further aspect of the method, forming the resilient member includes stamping a spring form from sheet metal.

[0022] According to another aspect of the method, the sheet metal may be thin film sputtered nitinol, cold worked nitinol, beryllium copper alloy, cobalt chromium alloy, or stainless steel alloy.

[0023] According to one aspect of the method, the shape setting is performed by heating the sheet metal in an oven.

[0024] According to a further aspect of the method, the shape setting is performed by hot forming the sheet metal as part of a stamping process.

[0025] According to a further aspect of the method, the stamping includes progressive stamping with a series of dies. [Brief description of the drawings]

[0026] For a better understanding of the invention, reference is now made, by way of example, to the detailed description thereof, which should be read in conjunction with the following drawings, in which like elements are given like reference numerals and in which: [Figure 1] 1 is a pictorial diagram of a system for performing a catheterization procedure in the heart, in accordance with a disclosed embodiment of the invention; [Diagram 2] 1 is a schematic diagram of a distal portion of a cardiac catheter having a contact force sensor in accordance with an embodiment of the present invention. [Diagram 3] FIG. 2 is an elevational view of a spring mold prior to shape fixing, in accordance with an embodiment of the present invention. [Figure 4] 4 is a side view of the mold shown in FIG. 3 after shape fixing, in accordance with an embodiment of the present invention. [Diagram 5] FIG. 5 is a perspective side view of the mold shown in FIG. 4 in accordance with an embodiment of the present invention. [Figure 6] FIG. 13 is a perspective view of a shape-fixed spring according to an alternative embodiment of the present invention. [Figure 7] 7 is a more tilted elevational view of the shape-fixed spring shown in FIG. 6 according to an alternative embodiment of the present invention. [Figure 8]FIG. 13 is an elevational view of a compression spring installed between two cylinders in accordance with an alternative embodiment of the present invention. [Figure 9] 13 illustrates a spring type and shape-fixed spring according to an alternative embodiment of the present invention. [Figure 10] 1 illustrates a shape-fixed spring according to an alternative embodiment of the present invention. [Figure 11] 1 illustrates a shape-fixed spring according to an alternative embodiment of the present invention. [Figure 12] 1 illustrates a shape-fixed spring according to an alternative embodiment of the present invention. [Figure 13] 13 illustrates a spring type and shape-fixed spring according to an alternative embodiment of the present invention. [Figure 14] 1 illustrates a shape-fixed spring according to an alternative embodiment of the present invention. [Figure 15] 1 illustrates a shape-fixed spring according to an alternative embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] In the following description, numerous specific details are set forth to provide a thorough understanding of the various principles of the present invention. However, it will be apparent to those skilled in the art that not all of these details are necessary to practice the present invention. In this instance, well-known circuits, control logic, and details of computer program instructions for conventional algorithms and processes have not been shown in detail so as not to unnecessarily obscure the general concepts.

[0028] Documents incorporated herein by reference are to be considered as integral parts of this application and, except where any term is defined in those incorporated documents to the contrary to a definition expressly or impliedly given herein, only the definition in this specification should be considered.

[0029] System Overview Turning now to the drawings, and referring initially to FIGURE 1, which is a pictorial diagram of a system 10 for assessing electrical activity and performing an ablation procedure in a living subject's heart 12, constructed and operative in accordance with a disclosed embodiment of the present invention. The system includes a catheter 14 that is percutaneously inserted by an operator 16 through the subject's vascular system into a chamber or vascular structure of the heart 12. The operator 16, typically a physician, brings a distal tip 18 of the catheter into contact with the heart wall, for example, at an ablation target site. Electrical activity maps may be generated according to methods disclosed in U.S. Pat. Nos. 6,226,542 and 6,301,496, and commonly assigned U.S. Pat. No. 6,892,091, the disclosures of which are incorporated herein by reference. One commercially available product embodying elements of system 10 is available as the CARTO® 3 system, available from Biosense Webster, Inc., 3333 Diamond Canyon Road, Diamond Bar, Calif. 91765. This system may be modified by one of skill in the art to embody the principles of the invention as described herein.

[0030] Regions determined to be abnormal, for example by evaluation of electrical activity maps, can be ablated by applying thermal energy, for example by applying radio frequency energy to the myocardium, or by passing radio frequency current through wires in the catheter to one or more electrodes at the distal tip 18. The energy is absorbed by the tissue, heating it to a level (usually about 60° C.) that permanently eliminates the tissue's electrical excitability. If successful, this procedure creates non-conducting lesions in the cardiac tissue that interrupt the abnormal electrical pathways that cause the arrhythmia. The principles of the present invention can be applied to different cardiac chambers to diagnose and treat a number of different cardiac arrhythmias.

[0031] The catheter 14 typically includes a handle 20 having suitable controls thereon to enable the operator 16 to steer, position, and orient the distal portion of the catheter as desired for ablation. To assist the operator 16, the distal portion of the catheter 14 contains a position sensor (not shown) that provides signals to a processor 22 located in a console 24. The processor 22 may perform several processing functions, as described below. Additionally, the catheter 14 includes a contact force sensor, which is described below.

[0032] Ablation energy and electrical signals can be delivered to / from the heart 12 through one or more ablation electrodes 32 located at or near the distal tip 18 via cables 34 to the console 24. Pacing and other control signals can be delivered from the console 24 through the cables 34 and the electrodes 32 to the heart 12. Sensing electrodes 33, also connected to the console 24, are positioned between the ablation electrodes 32 and have connections to the cables 34.

[0033] Wire connections 35 connect the console 24 to the body surface electrodes 30 and other components of a positioning subsystem for measuring position and orientation coordinates of the catheter 14. The processor 22 or another processor (not shown) may be an element of the positioning subsystem. The electrodes 32 and the body surface electrodes 30 may be used to measure tissue impedance at the ablation site as taught in U.S. Pat. No. 7,536,218 issued to Govari et al., which is incorporated herein by reference. A temperature sensor (not shown), typically a thermocouple or thermistor, may be placed on or near each of the electrodes 32.

[0034] The console 24 typically houses one or more ablation power generators 25. The catheter 14 may be adapted to deliver ablation energy to the heart using any known ablation technique, such as, for example, radiofrequency energy, ultrasonic energy, and laser-generated light energy. Such methods are disclosed in commonly assigned U.S. Patent Nos. 6,814,733, 6,997,924, and 7,156,816, which are incorporated herein by reference.

[0035] In one embodiment, the positioning subsystem includes a magnetic position tracking arrangement that uses field generating coils 28 to generate magnetic fields within a predefined working volume and senses these fields at the catheter to determine the position and orientation of the catheter 14. The positioning subsystem is described in U.S. Patent No. 7,756,576, which is incorporated herein by reference, and U.S. Patent No. 7,536,218, cited above.

[0036] As mentioned above, catheter 14 is coupled to a console 24, which allows operator 16 to observe and adjust the functions of catheter 14. Console 24 includes a processor, preferably a computer having suitable signal processing circuitry. The processor is coupled to drive a monitor 29. The signal processing circuitry typically receives, amplifies, filters, and digitizes signals from catheter 14, including, for example, signals generated by sensors, such as electrical, temperature, and contact force sensors, located distally within catheter 14, as well as a number of position sensing electrodes (not shown). The digitized signals are received by console 24 and a positioning system and used to calculate the position and orientation of catheter 14 and to analyze the electrical signals from the electrodes.

[0037] To generate the electroanatomical map, the processor 22 typically includes an electroanatomical map generator, an image registration program, an image or data analysis program, and a graphical user interface configured to present graphical information on the monitor 29.

[0038] System 10 typically also includes other elements, not shown for simplicity. For example, system 10 may include an electrocardiogram (ECG) monitor coupled to receive signals from one or more body surface electrodes to provide ECG-synchronized signals to console 24. As noted above, system 10 typically also includes a reference position sensor, either an externally applied reference patch attached to the outside of the patient's body, or an internally-placed catheter inserted into heart 12 while maintained in a fixed position relative to heart 12. Catheter 14 is provided with conventional pumps and lines for circulating liquid through it for cooling the ablation site. System 10 may receive image data from an external imaging modality, such as an MRI unit, and may include an image processor that may be incorporated or called upon by processor 22 for generating and displaying images.

[0039] Reference is now made to FIG. 2, which is a schematic diagram of a distal end portion of a cardiac catheter 37, in accordance with an embodiment of the present invention. A contact force sensor configured in accordance with an embodiment of the invention is disposed on a portion 39 of the catheter. Except for the contact force sensor, the catheter 37 may be a catheter as described in commonly assigned U.S. Patent Application Publication No. 2009 / 0093806 to Govari et al., the contents of which are incorporated herein by reference. The catheter 37 is a flexible insertion tube having a distal portion 41 for insertion into a body cavity of a patient and a distal tip 43 configured to be contacted with tissue within the body cavity. A resilient member 45 couples the proximal portion 47 to the distal portion 41. In this disclosure, members such as the proximal portion 47 and the distal portion 41 are members that move relative to each other and that attach to the resilient member 45, also referred to as "connecting elements." The terms "proximal" and "distal" are arbitrarily used herein to distinguish between portions of a catheter. These terms have no physical meaning with respect to the actual configuration of the catheter itself.

[0040] The distal portion 41 is capable of moving and bending relative to the proximal portion 47 in response to pressure exerted on the distal tip 43, indicated by arrow 49. In the embodiment of FIG. 2, the resilient member 45 is interposed between two connecting elements 46 and 48. The legs 50, 52 extend in opposite perpendicular directions from the plane of the ring portion 54 and contact the end faces of the connecting elements 46, 48 such that the electromagnetic coils are spaced apart by a distance that may be as little as 0.1 mm. Electromagnetic coils 62, 64 are provided on either side of the resilient member 45 to measure the displacement of the distal tip 43 relative to the proximal portion 47 of the catheter 37 as the resilient member 45 deforms in response to tip pressure.

[0041] First embodiment Referring now to FIG. 3, it is an elevational view of a spring mold 51 before shape setting, according to an embodiment of the present invention. The mold is cut from a sheet metal, such as thin film sputtered or cold worked Nitinol, and then formed or shape set to the desired shape. Alternatively, the mold may be made from a beryllium copper alloy, a cobalt chrome alloy, or a stainless steel alloy. One way to achieve shape setting is to expose the mold to high temperatures in an oven. The temperature and other operating conditions required for shape setting are well known in the art according to the material used for the spring, for example Nitinol is typically heated to a high temperature of 520° C. for 30 minutes and then quenched. Alternatively, the sheet metal may be subjected to progressive stamping, for example, performing a series of operations on the metal with different dies until a completed spring shape is achieved. The mold 51 has a central ring portion 53 forming a closed curve surrounding an inner open space 55 with a corrugated contour. Six legs 57 radiate outwardly from the open space 55. Stamping may include hot forming a metal.

[0042] Referring again to Figure 2, the ring portion 54 constitutes a resilient portion that acts as a compression spring between the proximal portion 47 and the distal portion 41 of the catheter 37. The spring action correlates a compressive force with the displacement of the distal portion 41 relative to the proximal portion 47. The legs 50, 52 form the attachments to the connecting elements 46, 48. In the embodiment of Figure 2, the legs 50, 52 provide the desired separation between the distal portion 41 and the proximal portion 47. In one type of catheter, the electrodes are in the distal portion and the catheter shaft forms the proximal portion.

[0043] 4 and 5, which are respectively a side view and a perspective view of the mould 51. The mould 51 is shape-fixed in a rest position according to an embodiment of the present invention. The legs 57 are bent at an angle of 90° to the plane 58 (shown in dashed lines) of the ring portion 53 in alternating directions. Furthermore, a segment of the ring portion 53 is disposed on one side of the plane 58. When a compressive force is applied to the legs 57 as shown by the arrows 59, the ring portion 53 undergoes a deformation, the ring portion 53 tends to approach a flattened state, and all portions approach or lie on the plane 58. When the compressive force is removed, the ring portion 53 returns to the configuration of FIG. 4.

[0044] This and the following embodiments can be mass produced, lowering unit costs. Designs are cut, stamped, or otherwise shaped from flat sheet metal and then shape-set into their final configuration. Typical thickness dimensions for such springs in cardiac catheter applications are approximately 0.5 mm. Minimizing the thickness of the elastic portion of the spring is important in cardiac catheters because the two connecting elements typically comprise a transmitter and a receiver, which can now be separated by a distance not exceeding 1.5 mm. Furthermore, by laser cutting the sheet metal into a pattern, welding is eliminated, thereby not only keeping unit costs low, but also improving reliability compared to traditional welded springs.

[0045] Second embodiment 6 and 7, both are elevational views of a shape-fixed spring 61 according to an alternative embodiment of the present invention. In this embodiment, the legs 63 are connected to the central ring 65 by connectors 67 that form angles 69, 73 on either side of the plane of the central ring 65, typically 26 degrees out of the plane. The connectors 67 include fenestrations 71 that increase the axial displacement but have minimal effect on the radial (or lateral) displacement. When a compressive force is applied to the legs 63, it reduces the angles 69, 73, and when the compressive force is removed, it is reversed.

[0046] Third embodiment 8, which is an elevational view of a compression spring 75 installed between two cylinders 77, 79 in accordance with an alternative embodiment of the present invention. The spring 75 may be any of the embodiments herein. A central portion 81 of the spring itself functions as a compression spring as described above. The cylinders 77, 79 are embraced by legs 83 that have a retaining or gripping feature to secure the spring 75 to the cylinders 77, 79.

[0047] Fourth embodiment 9, which illustrates a spring mold 85 and a shape-fixed spring 87 prepared from the spring mold 85 in accordance with an alternative embodiment of the present invention. In this embodiment, legs 89 extend from a central ring 91 and bifurcate at junction 93 to form branches 95, 97.

[0048] Spring 87 has four legs 89 bent above and below the plane of ring 91 as described in previous embodiments. In some applications, legs 89 maintain spacing between respective contact structures, such as distal portion 41 and proximal portion 47 of catheter (FIG. 1). Branches 95, 97 can be bent inward for other applications to provide a holding or gripping function similar to spring 75 (FIG. 8).

[0049] Fifth embodiment 10, which illustrates a shape-fixed spring 99 in accordance with an alternative embodiment of the present invention. The structure of the spring 99, having four legs 101, is similar to spring 87 (FIG. 9), except that the central ring 103 is shaped into a sinusoidal configuration that oscillates generally radially toward and away from a midpoint 105 of the central ring 103. The overall length dimension exceeds the circumference of a circular ring of the same diameter and allows for closer placement between the transmitter coil and the receiver coil.

[0050] Sixth embodiment Reference is now made to Figure 11, which shows a shape-fixed spring 107 according to an alternative embodiment of the present invention. This variation is similar to the embodiment of Figure 10, except that the sectors 109 (one of the sectors 109 is shown in dashed lines) of the central ring 111 connecting the legs 113 are made into two hairpin curves. The springs 107 can act as compression springs as described above, and may also function to allow lateral (or radial) movement.

[0051] Seventh embodiment 12, which illustrates a shape-fixed spring 121 according to an alternative embodiment of the present invention. The arrangement is similar to spring 99 (FIG. 10), except that there are six legs 123 instead of four. This design allows spring 121 to withstand relatively large compressive forces compared to spring 99.

[0052] Eighth embodiment 13, which shows a spring form 125 and a shape-set spring 127 prepared from spring form 85 in accordance with an alternative embodiment of the present invention. In this embodiment, six legs 129 are attached to outwardly directed loops 131 molded into a central ring 133. As shown on the left side of FIG. 13, the six legs 129 extend inwardly toward the center 130 of the central ring, which reduces the outer diameter of the final molded spring form 125.

[0053] Ninth embodiment 14, which illustrates a shape-set spring 135 according to an alternative embodiment of the present invention. This embodiment is similar to spring 61 (FIG. 6), except that the links 137 connecting the legs 139 with the central ring 141 are solid rather than fenestrated, which makes the process simpler for a metal stamping operation.

[0054] Tenth embodiment 15, which illustrates a shape-fixed spring 143 according to an alternative embodiment of the present invention. In this embodiment, there are six legs 145 attached to respective elongated loops 147 extending from a central ring 149. In addition to the loops 147, the ring 149 includes additional outwardly extending loops 151 that alternate with the loops 147 and are not attached to the legs. The additional loops reduce stiffness and distribute stress over a larger area, resulting in a more robust design.

[0055] Those skilled in the art will appreciate that the present invention is not limited to what has been particularly shown and described above, but rather, the scope of the present invention includes combinations and subcombinations of the various features described above, as well as variations and modifications of the above features that are not present in the prior art and that would occur to those skilled in the art upon reading the above description.

[0056] [Embodiment] (1) An apparatus comprising: a spring having a resilient member interposed between two contacting elements, said resilient member, and An apparatus in which an extension connected to the resilient member is in contact with the elements, and a force applied to at least one of the elements causes a deformation of the spring that correlates with the displacement of the elements relative to one another. (2) The device of embodiment 1, wherein the elastic member comprises a central ring having a first segment and a second segment, the first segment being disposed on one side of a plane and the second segment being disposed on another side of the plane, and the deformation includes moving the first segment and the second segment closer to the plane. (3) The apparatus of claim 1, wherein the resilient member comprises a central ring having a sinusoidal configuration with radial vibration toward and away from a midpoint of the ring. (4) The device of embodiment 1, wherein the elastic member comprises a central ring having a plurality of sectors, each of the sectors being shaped into two hairpin curves. (5) The device of claim 4, wherein the deformation includes twisting of at least one of the elements relative to another of the elements.

[0057] (6) The device of embodiment 1, wherein the extension portion comprises a plurality of legs attached to a central ring, including a first leg and a second leg, the first leg and the second leg extending in opposite first and second perpendicular directions, respectively, relative to the ring. (7) The device of embodiment 6, further comprising a first link and a second link connecting the first leg and the second leg, respectively, to the ring at opposite angles relative to a plane, and the deformation includes a reduction in the angle. (8) The device of embodiment 7, wherein the first leg and the second leg contact end faces of the respective elements. (9) The device of embodiment 7, wherein the first leg and the second leg embrace respective elements. (10) An apparatus comprising: a flexible insertion tube having a proximal portion and a distal portion for insertion into a body cavity of a patient; a resilient member coupling the proximal portion to the distal portion of the insertion tube, the resilient member comprising a shape-set elastic material, the resilient member having proximal and distal extensions in contact with the proximal and distal portions of the insertion tube, respectively; A device wherein a force applied through the distal portion causes a deformation of the resilient member that correlates with a displacement of the proximal portion relative to the distal portion.

[0058] (11) The device of embodiment 10, wherein the elastic member comprises a central ring having a first segment and a second segment, the first segment disposed on one side of a plane and the second segment disposed on another side of the plane, and the deformation comprises moving the first segment and the second segment closer to the plane. (12) The apparatus of claim 10, wherein the resilient member includes a central ring having a sinusoidal configuration with radial vibrations toward and away from a midpoint of the ring. (13) The resilient member comprises a central ring having a plurality of sectors; The apparatus of embodiment 10, wherein each of the sectors is wound into two hairpin curves. (14) The device of embodiment 13, wherein the proximal portion is spaced from the distal portion and the elastic member is interposed therebetween, and the deformation is caused by twisting of the proximal portion relative to the distal portion. (15) The device of embodiment 10, wherein the resilient member comprises a central ring, and the proximal and distal extensions extend in opposite first and second perpendicular directions, respectively, relative to the ring.

[0059] (16) The device of claim 15, further comprising a first connector and a second connector respectively connecting the proximal and distal extensions to the ring at an angle relative to a plane, and the deformation comprises a change in the angle. (17) The device of claim 16, wherein the proximal and distal portions have end faces, and the proximal and distal extensions contact the end faces of the proximal and distal portions, respectively. (18) The device of claim 16, wherein the proximal and distal extensions embrace the proximal and distal portions, respectively. (19) A method for manufacturing a medical probe, comprising the steps of: providing an elongate probe having a proximal portion and a distal portion having an electrode thereon; forming a resilient member from sheet metal, the resilient member having a resilient portion and an attachment portion, the attachment portion configured to engage the proximal portion and the distal portion of the probe; shape fixing the resilient member; configuring the resilient member as a contact force sensor by coupling the resilient member to the proximal and distal portions such that a force applied through the distal portion causes a deformation of the resilient member that correlates with a displacement of the proximal portion relative to the distal portion; A method comprising: (20) The method of claim 19, wherein forming the resilient member includes cutting a spring form from sheet metal.

[0060] (21) The method of embodiment 20, wherein the cutting is performed by laser cutting. (22) The method of claim 19, wherein forming the resilient member includes stamping a spring form from sheet metal. 23. The method of claim 19, wherein the metal sheet comprises one of the group consisting of thin film sputtered nitinol, cold worked nitinol, beryllium copper alloy, cobalt chromium alloy, and stainless steel alloy. (24) The method of claim 19, wherein the shape fixing is performed by heating the metal sheet in an oven. 25. The method of claim 19, wherein shape-setting is performed by hot forming the sheet metal as part of a stamping process.

[0061] (26) The method of claim 25, wherein the stamping comprises progressive stamping with a series of dies.

Claims

1. An apparatus comprising: a flexible insertion tube having a proximal portion and a distal portion for insertion into a body cavity of a patient; a resilient member coupling the proximal portion to the distal portion of the insertion tube, the resilient member comprising a shape-set elastic material, the resilient member having a ring-shaped body portion with a central opening and a plurality of proximal and distal extensions extending from an outer edge of the ring-shaped body portion and in contact with the proximal and distal portions of the insertion tube, respectively, the proximal and distal extensions extending alternately from the outer edge of the ring-shaped body portion in sequence along the outer edge; a force applied to the distal portion displaces the distal portion relative to the proximal portion causing deformation of the resilient member; each of the proximal extensions includes a first leg in contact with the proximal portion and each of the distal extensions includes a second leg in contact with the distal portion, the first legs extending in a proximal direction of the insertion tube and the second legs extending in a distal direction of the insertion tube.

2. The device of claim 1 , wherein the ring-shaped body portion of the resilient member comprises a central ring surrounding the central opening, the central ring having a plurality of curved portions that are curved in an undulating manner.

3. 2. The apparatus of claim 1, wherein the ring-shaped body portion of the resilient member comprises a central ring, the first leg and the second leg extending in opposite first and second perpendicular directions, respectively, relative to the central ring.

4. 4. The device of claim 3, wherein the resilient member further comprises a first link and a second link connecting the first leg and the second leg, respectively, to the central ring.

5. The device of claim 4 , wherein the proximal and distal portions have end faces, and the first and second legs contact the end faces of the proximal and distal portions, respectively.

6. The device of claim 4 , wherein the first leg and the second leg embrace the proximal portion and the distal portion, respectively.

7. 2. The device of claim 1, wherein the ring-shaped body portion of the resilient member comprises a central ring, the first leg and the second leg extending from the central ring and branching at junctions to form branches.

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