Medical probe with concentric reference and sense electrodes

Abstract

To provide an electrode combination for an end effector of a catheter.SOLUTION: An electrode combination for an end effector of a catheter may include a reference electrode and a sensing electrode that are positioned such that the reference electrode is recessed in relation to the sensing electrode so that the reference electrode is inhibited from contacting tissue while the sensing electrode is in contact with tissue. The reference electrode can function to detect far-field electromagnetic noise while the sensing electrode receives electrical signals from tissue and may also receive signals from far-field electromagnetic noise. Electrocardiograms of the electrical signals from tissue can be generated by subtracting, or otherwise compensating for, the far-field noise received by the sensing electrode based on the far-field electromagnetic noise received by the reference electrode. Preferably, the reference electrode and the sensing electrode have the same surface area as each other.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to the earlier application U.S. Provisional Application No. 63 / 507,154 (Attorney Docket No. BIO6819USPSP1), filed June 9, 2023, which is incorporated by reference as if set forth in its entirety herein.

[0002] FIELD OF THEINVENTION The present disclosure relates generally to medical devices, and more particularly to electrode catheters configured to measure electrical signals in tissue, especially cardiac tissue. [Background technology]

[0003] Cardiac arrhythmias, such as atrial fibrillation (AF), occur when an area of ​​cardiac tissue abnormally conducts electrical signals to adjacent tissue. This disrupts the normal cardiac cycle and causes an asynchronous rhythm. Certain procedures that exist for treating arrhythmias include surgically destroying the source of the signals that cause the arrhythmia and destroying the conduction pathways of such signals. By selectively ablating cardiac tissue with the application of energy via a catheter, it is sometimes possible to stop or alter the propagation of unwanted electrical signals from one part of the heart to another.

[0004] Many current ablation approaches utilize radiofrequency (RF) electrical energy to heat tissue. RF ablation can have certain rare drawbacks due to operator skill, such as increased risk of thermal cell damage that can lead to tissue charring, burning, steam popping, phrenic nerve paralysis, pulmonary vein stenosis, and esophageal fistula. Cryoablation is an alternative approach to RF ablation that reduces some of the thermal risks associated with RF ablation, but may present tissue damage due to the ultra-low temperature nature of such devices. Manipulating cryoablation devices and selectively applying cryoablation is generally more difficult compared to RF ablation, and thus cryoablation is not feasible in certain anatomical geometries that can be reached by electrical ablation devices.

[0005] Ablation approaches have been developed that use irreversible electroporation (IRE) to ablate cardiac tissue using non-thermal ablation methods. To achieve IRE, short pulses of high-voltage electrical signals are delivered to tissue, which results in irreversible permeabilization of cell membranes. Delivery of IRE energy to tissue using multi-electrode catheters has been previously proposed in the patent literature. Examples of systems and devices configured for IRE ablation are disclosed in U.S. Patent Application Publication Nos. 2021 / 0169550(A1), 2021 / 0169567(A1), 2021 / 0169568(A1), 2021 / 0161592(A1), 2021 / 0196372(A1), 2021 / 0177503(A1), and 2021 / 0186604(A1), each of which is incorporated by reference into this specification. Nos. 2021 / 0169550(A1), 2021 / 0177503(A1), and 2021 / 0186604(A1), the disclosures of which are incorporated herein by reference, are attached as an appendix to priority patent application No. 63 / 507,154.

[0006] Regions of cardiac tissue can be mapped by catheters to identify abnormal electrical signals. Ablation may be performed using the same or different catheters. Some catheter ablation procedures, particularly those involving persistent atrial fibrillation, may be performed using electrophysiology (EP) mapping to target regions of abnormal electrical signals. Such EP mapping may include the use of sensing electrodes configured to monitor electrical signals within the cardiovascular system to pinpoint the location of abnormal conductive tissue sites involved in the arrhythmia. An example of an EP mapping system is described in U.S. Pat. No. 5,738,096, which is incorporated herein by reference and attached in an appendix to priority patent application Ser. No. 63 / 507,154. Examples of EP mapping catheters are described in U.S. Pat. No. 9,907,480, U.S. Patent Publication Nos. 2018 / 0036078, 2018 / 0056038, and 20210369339, each of which is incorporated herein by reference and attached in an appendix to U.S. Priority Application No. 63 / 507,154.

[0007] In addition to using EP mapping, some catheter ablation procedures may be performed using an image guided surgery (IGS) system. An IGS system may allow a physician to visually track the position of the catheter within the patient in real time in conjunction with an image of the patient's anatomy. Some systems may provide a combination of EP mapping and IGS functionality, including the CARTO™ 3 system by Biosense Webster, Inc. (Irvine, Calif.). An example of a catheter configured for use with an IGS system is disclosed in U.S. Pat. No. 9,480,416, which is incorporated herein by reference and attached as an appendix to priority patent application Ser. No. 63 / 507,154. Summary of the Invention [Means for solving the problem]

[0008] An electrode combination for the end effector of the presented catheter may include a reference electrode and a sensing electrode, the reference electrode being positioned to be recessed relative to the sensing electrode such that the reference electrode is prevented from contacting the tissue while the sensing electrode is in contact with the tissue. The reference electrode may function to detect far-field electromagnetic noise, and the sensing electrode may receive electrical signals from the tissue and may also receive signals from the far-field electromagnetic noise. An electrogram of the electrical signal from the tissue may be generated based on the far-field electromagnetic noise received by the reference electrode and by subtracting or otherwise compensating for the far-field noise received by the sensing electrode. Preferably, the reference electrode and the sensing electrode have the same surface area as each other.

[0009] An exemplary end effector for a medical probe can include a first electrode and a second electrode. The first electrode can be disposed on a first side of the end effector. The first electrode can have a first surface exposed to the surrounding environment and configured to contact tissue. The second electrode can be disposed on the first side of the end effector. The second electrode can be at least partially surrounded by the first electrode. The second electrode can have a second surface exposed to the surrounding environment, the second surface prevented from contacting tissue by a first vertical gap between the first and second surfaces.

[0010] Another exemplary end effector for a medical probe can include a frame, a first electrode, and a second electrode. The frame member can extend along a longitudinal axis. The first electrode and the second electrode can be disposed generally perpendicular to the longitudinal axis of the frame member, with one of the first electrode and the second electrode recessed relative to the other of the first electrode and the second electrode to prevent such recessed electrode from contacting tissue.

[0011] An exemplary medical probe may include an elongate shaft, an end effector, and a plurality of electrode combinations. The elongate shaft may extend along a longitudinal axis. The end effector may be coupled to a distal end of the shaft assembly. The plurality of electrode combinations may be coupled to the end effector. Each electrode combination of the plurality of electrode combinations may include a respective inner electrode and a respective outer electrode disposed about at least a majority of the respective inner electrode and vertically offset from the respective inner electrode. Each of the respective inner electrode and each respective outer electrode may be exposed to the surrounding environment.

[0012] An exemplary method for reducing far-field signals can include the following steps, performed in various orders and with interleaving steps, as will be appreciated by those skilled in the art: The method can include arranging a first electrode and a second electrode on a generally planar member such that one of the first electrode and the second electrode is recessed relative to the other of the first electrode and the second electrode. The method can include sensing the far-field signal using the recessed one of the first electrode and the second electrode. The method can include sensing a cardiac signal using the other of the first electrode and the second electrode. The method can include subtracting the far-field signal from the cardiac signal. [Brief description of the drawings]

[0013] The specification concludes with claims particularly pointing out and distinctly claiming the subject matter described herein, which subject matter will be better understood from the following description of specific embodiments taken in conjunction with the accompanying drawings, in which like reference numerals identify the same elements, and in which: The figures depict one or more implementations of the device of the present invention, by way of illustration only and not by way of limitation. [Figure 1] FIG. 1 illustrates an exemplary catheter-based electrophysiological mapping and ablation system. [Diagram 2] 1A-1C are diagrams of an exemplary end effector of a catheter. [Figure 3A] 13A-13C are diagrams of an exemplary end effector having alternative electrode configurations. [Figure 3B] FIG. 2 is a diagram of an exemplary end effector frame. [Figure 4] FIG. 3B is a cross-sectional view of the exemplary end effector shown in FIG. 3A. [Figure 5A] FIG. 5 is a top view of the electrode combination of the end effector shown in FIG. 4. [Figure 5B] FIG. 5 is a top view of the electrode combination of the end effector shown in FIG. 4. [Figure 5C] FIG. 5 is a top view of the electrode combination of the end effector shown in FIG. 4. [Figure 6] 13A-13C are cross-sectional views of an exemplary end effector having additional structural members around the perimeter of the frame. [Figure 7] 13A-13C are diagrams of an exemplary end effector having an alternative electrode support structure. [Figure 8A] FIG. 8 is a diagram of an alternative embodiment of a cross section of the electrode combination shown in FIG. 7. [Figure 8B] FIG. 8 is a diagram of an alternative embodiment of a cross section of the electrode combination shown in FIG. 7. [Figure 8C] FIG. 8 is a diagram of an alternative embodiment of a cross section of the electrode combination shown in FIG. 7. [Figure 9] FIG. 13 illustrates an exemplary flex circuit layout that can be used to support an electrode combination of an exemplary end effector. [Figure 10] 1 is a flow diagram of method steps that can be used to detect a cardiac signal. [Figure 11A] 1 illustrates an example magnetic sensor circuit for an end effector. [Figure 11B] 1 illustrates an example magnetic sensor circuit for an end effector. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The following detailed description should be read with reference to the drawings, in which like elements in different drawings are numbered the same. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. The detailed description illustrates, by way of example and not by way of limitation, the principles of the invention. The description clearly enables one skilled in the art to make and use the invention and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what is currently contemplated to be the best mode for carrying out the invention.

[0015] As used herein, the term "about" or "approximately" in relation to any numerical value or range indicates a suitable dimensional tolerance that enables a portion or collection of components to function for the intended purpose described herein. More specifically, "about" or "approximately" may refer to a range of values ​​of ±10% of the recited value, for example, "about 90%" may refer to a range of values ​​of 81% to 99%.

[0016] Additionally, as used herein, the terms "patient," "host," "user," and "subject" refer to any human or animal subject, and while use of the invention in a human patient represents a preferred embodiment, it is not intended to limit the systems or methods to human use. Similarly, the term "proximal" refers to a location closer to the operator, while "distal" refers to a location further away from the operator or physician.

[0017] Alternative apparatus and system features and alternative method steps are presented in the exemplary embodiments herein. Each given exemplary embodiment presented herein can be modified to include features and / or method steps presented with different exemplary embodiments herein, and such features and / or steps are compatible with the given embodiment as understood by those skilled in the art and as explicitly set forth herein. Such modifications and variations are intended to be included within the scope of the claims.

[0018] FIG. 1 illustrates an exemplary catheter-based electrophysiology mapping and ablation system 10. The system 10 includes multiple catheters that are percutaneously inserted by a physician 24 through a patient's vascular system into a cavity or vasculature of a heart 12. Typically, a delivery sheath catheter is inserted into the left or right atrium near a desired location within the heart 12. Multiple catheters can then be inserted into the delivery sheath catheter to reach a desired location. The multiple catheters may include catheters dedicated to sensing Intracardiac Electrogram (IEGM) signals, catheters dedicated to ablation, and / or catheters configured for both sensing and ablation. An exemplary catheter 14 configured for sensing IEGMs is illustrated herein. The physician 24 brings an end effector 100 of the catheter 14 into contact with the heart wall to sense a target site of the heart 12. For ablation, the physician 24 similarly brings a distal end of an ablation catheter to a target site for ablation.

[0019] The illustrated catheter 14 is an exemplary catheter including one, and preferably multiple, electrodes configured as an electrode combination 130 distributed across a substantially planar surface of the end effector 100 and configured to sense IEGM signals. Each electrode combination 130 may include a pair of electrodes vertically offset from one another such that one electrode is blocked from contacting tissue and the other electrode is in contact with tissue. The electrode in contact with tissue may function as a sensing electrode and the electrode blocked from contacting tissue may function as a reference electrode. The electrical signal received by the sensing electrode may include primarily IEGM signals, while the electrical signal received by the reference electrode may include primarily far-field signals. The IEGM signals may be more accurately measured by subtracting the signal received by the reference electrode from the signal received by the sensing electrode or by reducing far-field noise in the signal from the sensing electrode based on the signal from the reference electrode. The IEGM signals measured by the multiple electrode combinations 130 may be used to determine the spatial relationship of the IEGM signals through tissue.

[0020] The catheter 14 may further include a position sensor 29 coupled to the shaft 90 of the catheter 14 near the end effector 100 for tracking the position and orientation of the end effector 100. Optionally and preferably, the position sensor 29 is a magnetic-based position sensor including three magnetic coils for sensing three-dimensional (3D) position and orientation. The end effector 100 may include additional single-axis magnetic sensors 171, 172, 181 as shown in Figures 11A and 11B, variations thereof, and alternatives thereof, as will be understood by those skilled in the art.

[0021] The magnetic-based position sensors 29, 171, 172, 181 may operate in conjunction with a location pad 25 that includes a plurality of magnetic coils 32 configured to generate a magnetic field within a predetermined working volume. The real-time position of the end effector 100 of the catheter 14 may be tracked based on the magnetic fields generated by the local pad 25 and sensed by the magnetic-based position sensors 29, 171, 172, 181. Details of magnetic based position sensing techniques are described in U.S. Pat. Nos. 5,391,199, 5,443,489, 5,558,091, 6,172,499, 6,239,724, 6,332,089, 6,484,118, 6,618,612, 6,690,963, 6,788,967, and 6,892,091, which are incorporated herein by reference.

[0022] The system 10 includes one or more electrode patches 38 positioned for skin contact on the patient 23 to establish a position reference for the location pads 25, as well as impedance-based tracking of the electrodes, including the shaft electrodes 26 and / or electrodes of the end effector electrode combination 130. For impedance-based tracking, a current is directed to the electrodes 26, 130 and sensed at the electrode skin patch 38, so that the position of each electrode can be triangulated via the electrode patch 38. Details of impedance-based position tracking techniques are described in U.S. Patent Nos. 7,536,218, 7,756,576, 7,848,787, 7,869,865, and 8,456,182, which are incorporated herein by reference.

[0023] Recorder 11 displays electrograms 21 captured by the body surface ECG electrodes 18 and intracardiac electrograms (IEGMs) captured by electrode combination 130 of catheter 14. Recorder 11 may include pacing capability for pacing the cardiac rhythm and / or may be electrically connected to a stand-alone pacer.

[0024] The system 10 may include an ablation energy generator 50 adapted to deliver ablation energy to one or more electrodes at the distal tip of a catheter configured for ablation. The energy generated by the ablation energy generator 50 may include, but is not limited to, radio frequency (RF) energy or pulsed field ablation (PFA) energy, including monopolar or bipolar high voltage DC pulses such as may be used to effect irreversible electroporation (IRE), or combinations thereof.

[0025] The patient interface unit (PIU) 30 is an interface configured to establish electrical communication between the catheters, the electrophysiological equipment, a power source, and a workstation 55 for controlling the operation of the system 10. The electrophysiological equipment of the system 10 may include, for example, multiple catheters, location pads 25, body surface ECG electrodes 18, electrode patches 38, an ablation energy generator 50, and a recorder 11. Optionally and preferably, the PIU 30 includes processing capabilities for performing real-time calculations of catheter location and for performing ECG calculations.

[0026] The workstation 55 includes a processor unit having memory, memory or storage loaded with appropriate operating software, and user interface capabilities. The workstation 55 can be configured to provide multiple functions, optionally including: (1) modeling the endocardial anatomical structures in three dimensions (3D) and rendering the model or anatomical map 20 for display on the display device 27; (2) displaying on the display device 27 activation sequences (or other data) compiled from recorded electrograms 21 with representative visual indicia or images superimposed on the rendered anatomical map 20; (3) displaying real-time locations and orientations of multiple catheters within the heart chambers; and (4) displaying on the display device 27 sites of interest, such as where ablation energy has been applied. One commercially available product embodying elements of the system 10 is available as the CARTO™ 3 system, commercially available from Biosense Webster, Inc., Irvine, Calif. 92168.

[0027] 2 is a more detailed view of the end effector 100. The shaft 90 of the catheter 14 extends along a longitudinal axis AA. The end effector 100 is coupled to a distal end of the elongated shaft 90. The end effector 100 is shown in a planar configuration such that features of the end effector 100 are orthogonal to a first orthogonal axis O1 that is orthogonal to the longitudinal axis AA, and features of the end effector are parallel to a plane that includes the longitudinal axis AA and a second orthogonal axis O2 that is orthogonal to the longitudinal axis AA and the first orthogonal axis O1.

[0028] The end effector 100 is configured to be folded to a diameter sized to fit within a sheath catheter for delivery to the heart 12, and is configured to expand to a planar configuration (or approximately planar with some curvature) when pushed distally out of the distal end of the sheath catheter and suspended in bodily fluids. For example, the end effector 100 can be folded by rolling or folding the outer portions 103 towards each other to spirally wrap the end effector 100 along the longitudinal axis AA. The end effector 100 can be held in this folded configuration by the delivery sheath catheter when the end effector is delivered therethrough. The end effector 100 can be moved from the planar configuration to the folded configuration when pulled proximally into the distal end of the sheath catheter.

[0029] The end effector 100 is sufficiently flexible such that when pressed against tissue, the end effector conforms to the tissue such that multiple electrodes of the end effector simultaneously contact the tissue. The end effector 100 is sufficiently flexible such that when pressed against a planar surface, the end effector 100 assumes a planar configuration as shown in FIG.

[0030] The end effector may include a frame 150 configured to provide structural support for the end effector 100 and facilitate movement of the end effector 100 into a planar configuration. The end effector may include one or more membranes 110, 120 extending between posts of the frame 150 (see also FIGS. 4 and 6). The membranes 110, 120 may form a substrate to which an electrode combination 130 may be coupled. The end effector has a first side 101a and a second side 101b (FIGS. 4 and 6). Each side 101a, 101b is exposed to the surrounding environment, and the electrodes of each electrode combination 130 include a surface exposed to the surrounding environment.

[0031] The end effector 100 may include openings 102, 105 to enhance the flexibility of the end effector 100. As shown, the end effector 100 includes an outer opening 102 that extends the majority of the length of the end effector, measured from the distal end of the shaft 90 to the distal end 106 of the end effector. The outer opening 102 separates left and right portions 103 of the end effector from a central portion 107 of the end effector. As shown, the end effector 100 includes a central opening 105 that extends less than half the length of the end effector 100. The openings 102, 105 are preferably elongated along a longitudinal axis AA between rows 138 (FIG. 3A) of electrode combinations 130.

[0032] As shown, the central portion 107 includes an array of electrode combinations 130 coupled to portions of the membranes 110, 120 that extend between the posts of the frame 150. Thus, the end effector 100 need not include a frame 150 below all of the electrode combinations 130. At least some of the electrode combinations 130 can be coupled to the membranes 110, 120 such that the frame does not extend below the electrode combinations 130.

[0033] As shown in more detail in the inset of FIG. 2, each electrode combination includes a first electrode 131 and a second electrode 132. The second electrode 132 is surrounded by the first electrode 131. As shown, the first electrode 131 is annular and the second electrode 132 is circular. For example, by way of non-limiting example, the following alternative geometric shapes are contemplated: the first electrode 131 can have a square annular shape and the second electrode 132 can have a square shape; the first electrode 131 can have a regular polygonal annular shape and the second electrode 132 can have a regular polygonal shape; or the first electrode 131 can have an elliptical annular shape and the second electrode 132 can have an elliptical shape. Furthermore, the first electrode 131 can be continuous or segmented. Additionally, the first electrode 131 may have a serpentine annular shape and / or may include annular shaped interference cuts to provide flexibility for the first electrode 131. Preferably, the majority of the periphery of the second electrode 132 is surrounded by the first electrode 131.

[0034] The electrode combination 130 includes two electrodes 131, 132 such that one electrode of the electrode combination 130 can function as a sensing electrode and the other electrode of the electrode combination 130 can function as a reference electrode. The reference electrode can function to detect far-field electromagnetic noise, and the sensing electrode can receive electrical signals from the tissue and also receive signals from the far-field electromagnetic noise. An electrogram of the electrical signals from the tissue can be generated by subtracting or otherwise compensating for the far-field noise received by the sensing electrode based on the far-field electromagnetic noise received by the reference electrode.

[0035] The electrodes 131, 132 in the electrode combination can be vertically offset such that the sensing electrode contacts tissue while the reference electrode is prevented from contacting tissue by a vertical gap between the exposed surfaces of the two electrodes 131, 132. Thus, the reference electrode is in contact with a fluid (e.g., blood) and the sensing electrode is in contact with tissue. In some examples, the first electrode 131 (the outer electrode) is configured as the sensing electrode and the second electrode 132 (the inner electrode) is configured as the reference electrode. Alternatively, the end effector 100 can be modified such that the second electrode 132 is vertically elevated relative to the first electrode 131 such that the first electrode 131 functions as the reference electrode and the second electrode 132 functions as the reference electrode. In some examples, the end effector 100 may include two types of electrode combinations: a first type of electrode combination 130 in which a first electrode 131 (outer electrode) is configured as a sensing electrode and a second electrode 132 (inner electrode) is configured as a reference electrode, and a second type of electrode combination 130 in which the first electrode 131 (outer electrode) is configured as a reference electrode and the second electrode 132 (inner electrode) is configured as a sensing electrode.

[0036] The electrode combinations 130 can be spaced apart from one another to form a longitudinal pair 141. Each longitudinal pair 141 can include two electrode combinations 130, both on the same side 101a, 101b of the end effector 100. Thus, the longitudinal pair 141 includes two sensing electrodes, one from each electrode combination 130 of the longitudinal pair. The sensing electrodes can be configured to measure electrocardiogram signals as a bipolar pair. For example, a first electrode 131 from each electrode combination 130 can be configured as a sensing electrode, and the first electrode 131 can be configured to measure electrocardiogram signals as a bipolar pair. As described above, a second electrode 132 in an electrode combination 130 can alternatively be configured as a sensing electrode, and the end effector can include both a first type electrode combination and a second type electrode combination 130. Thus, the bipolar pair function of the longitudinal pair 141 can be between two outer electrodes 131, between two inner electrodes 132, or between an outer electrode 131 and an inner electrode 132, depending on the type(s) of electrode combination in the longitudinal pair 141.

[0037] The electrode combinations 130 can be positioned to form orthogonal pairs 142. Each orthogonal pair 142 can include a first electrode combination 130 on a first side 101a of the end effector 100 and a second electrode combination 130 on a second side 101b of the end effector 100 opposite the first electrode combination 130. The orthogonal pairs 142 can be used to further compensate for far-field noise. While the sensing electrodes in one electrode combination are in contact with tissue, the reference electrodes in that same electrode combination are detecting far-field noise directly adjacent to the tissue, while the electrodes in the opposite electrode combination are detecting far-field noise in the blood in an orientation facing away from the tissue. Thus, in addition to using the signals from the respective reference electrodes to compensate for far-field noise in the signals detected by the sensing electrodes, the signals detected from the electrodes in the opposite electrode combination can also be used to compensate for far-field noise.

[0038] The end effector 100 may further include a flexible polymer layer 160 as an outer enclosure, which will be described in more detail in connection with FIG.

[0039] 3A is a diagram of an exemplary end effector 100 having an alternative electrode configuration. The electrode combinations 130 are spaced apart in a regular grid having rows 137 of electrode combinations 130 and columns 138 of electrode combinations. The rows 137 are aligned along a second orthogonal axis. The columns 138 are aligned along a longitudinal axis AA. The alternative electrode configuration does not include a longitudinal pair 141. The alternative electrode configuration includes an orthogonal pair 142. The orthogonal pair 142 is aligned vertically along a centerline CL along a first orthogonal axis O1 and is therefore orthogonal to the end effector 100 in a planar configuration. The electrode pairs 130 and the alignment are described in more detail in conjunction with FIG. 4.

[0040] 3B is an illustration of an exemplary end effector frame 150. The end effector may include a frame 150 configured to provide structural support for the end effector and facilitate movement of the end effector 100 to a planar configuration. The frame 150 may include a resilient material and may include a shape memory material, such as Nitinol. The frame 150 may be symmetrical about the longitudinal axis AA as shown, but need not be symmetrical about the longitudinal axis AA.

[0041] FIG. 4 is a cross-sectional view of the exemplary end effector 100 shown in FIG. 3A. The top surfaces 133, 134 of the first electrode 131 and the second electrode 132 are exposed to the surrounding environment, respectively. The top surfaces 133, 134 of the two electrodes 131, 132 are separated by a vertical gap H1. The vertical gap H1 prevents the top surface of the second electrode 132 from contacting the tissue while the top surface of the first electrode 131 is in contact with the tissue. When the first electrode 131 is pressed into the tissue, the tissue may have some elasticity such that it bends downward around the edge of the first electrode 131 and extends downward beyond the top surface 133 of the first electrode 131. The vertical gap H1 is large enough to prevent the tissue from extending downward to contact the top surface 134 of the second electrode 132 during a typical use case of the catheter 14.

[0042] 5A, 5B, and 5C are top views of various possible configurations of the electrode combination 130 of the end effector 100 shown in FIG. 4. FIG. 5A shows a first electrode 131 having an uninterrupted circular annular shape and a second electrode 132 having a continuous circular shape. FIG. 5B shows a first electrode 131 having an interrupted annular shape and a second electrode 132 having a polygonal shape. FIG. 5C shows a first electrode 131 having a serpentine continuous circular shape that may increase the flexibility of the first electrode 131. These are examples of some possible electrode shapes.

[0043] Dimensions such as the inner diameter D3 of the first electrode 131 may affect the minimum vertical gap H1 required to prevent tissue from contacting the upper surface 134 of the second electrode 132 during a typical use case of the catheter 14. The amount of force the end effector 100 is configured to apply to the tissue may also affect the minimum vertical gap H1 required to prevent tissue from contacting the upper surface 134 of the second electrode 132 during a typical use case of the catheter 14. The amount of force the end effector 100 is configured to apply to the tissue may be primarily influenced by the flexibility of the end effector 100, which may be primarily influenced by the flexibility of the frame 150. The flexibility of the tissue may also affect the minimum vertical gap H1 required to prevent tissue from contacting the upper surface 134 of the second electrode 132.

[0044] 4, 5A, 5B, and 5C collectively, a first surface area of ​​the upper surface 133 of the first electrode 131 can be calculated based on its dimensions (i.e., outer diameter D1, inner diameter D3, annular width W1, and shape). A second surface area of ​​the upper surface 134 of the second electrode 132 can be calculated by its dimensions (i.e., outer diameter D2 and shape). Preferably, the first surface area is approximately equal to the second surface area.

[0045] The first surface 133 and the second surface 134 can be laterally spaced apart from one another by a lateral gap region 136 having a gap length L1. The surface area of ​​the lateral gap region 136 can be calculated by taking the area of ​​a circle or polygon having a diameter equal to the inner diameter D3 of the first surface 133 and subtracting the area of ​​a circle or polygon having a diameter equal to the outer diameter D2 of the second surface 134. Thus, the surface area of ​​the lateral gap region 136 can be calculated as a planar surface area that is parallel to the first surface 133, parallel to the second surface 134, and lateral between the first and second surfaces. The surface area of ​​the lateral gap region 136 can be less than or equal to the first surface area of ​​the first surface 133 and less than or equal to the second surface area of ​​the second surface 134. The annular width W1 of the first surface 133 can be greater than or equal to the gap length L1. The outer diameter D2 of the second surface 134 can be greater than or equal to the gap length L1. Preferably, the lateral gap region 136 has a surface area approximately equal to about 0.83 times the second surface area and / or the first surface area.

[0046] In one example, the first electrode 131 has an outer diameter D1 of about 0.5 mm to about 0.67 mm, and the second electrode 132 has an outer diameter D2 of about 0.44 mm. In one example, the first and second surface areas are each about 0.15 mm. 2 It is.

[0047] Preferably, first surface 133 and second surface 134 are each planar and extend along longitudinal axis AA and face perpendicular to longitudinal axis AA as shown.

[0048] Referring to FIG. 4, the end effector 100 may include a frame 150, a first membrane 110 on a first side 101a of the end effector 100, a second membrane 120 on a second side 101b of the end effector 100, and an enclosure 160 covering the first and second membranes 110, 120.

[0049] The membranes 110, 120 may each include a depression or recess 112 in which the reference electrode is positioned to create a vertical gap H1 between the top surface of the sensing electrode and the top surface of the reference electrode. Although the recess 112 is shown as a circular recess, it may have alternative shapes according to the alternative shapes of the electrodes 131, 132 of the electrode combination 130.

[0050] As shown, the inner electrode 132 is disposed within the recess 112 and the outer electrode 131 surrounds the recess 112. Alternatively, the recess 112 may be configured to surround the inner electrode 132 and the outer electrode 131 may be positioned within the recess such that the outer electrode 131 is prevented from contacting tissue by the vertical gap H1 and is configured to function as a reference electrode while the inner electrode 132 is configured as a sensing electrode (FIG. 8B). The recess may include an overhang, as shown and disclosed in more detail in connection with FIG. 8A.

[0051] The membranes 110, 120 may include flex circuits, also referred to in the art as flexible printed circuit boards (PCBs) or flex PCBs. The membranes 110 may include a layer of flexible dielectric film, such as a polymer film, and one or more patterned conductive (e.g., metal) layers. Thus, the membranes 110, 120 may include multiple layers. In some examples, the polymer film may be made primarily of polyimide. In other examples, it may be made of biocompatible polyimide, glass-reinforced epoxy laminate material, copper, or graphene, either alone or in combination. To simplify the illustration, the layers of the membranes 110, 120 are not shown. Thus, the recesses 112 may be constructed by forming openings in one or more upper layers of the flex circuit and / or other polymer films of a given membrane 110, 120. As shown, the electrodes 131, 132 may include conductive disks electrically and mechanically coupled to the flex circuit. Additionally or alternatively, electrodes 131, 132 may include exposed portions of the conductive layer such that the conductive layer includes exposed top surfaces 133, 134.

[0052] As shown, the electrode combinations 130 in each orthogonal pair 142 are aligned vertically along a centerline CL along the first orthogonal axis O1, with the centerline CL passing through a center point of each electrode combination 130 of the orthogonal pair 142. The inner electrodes of the electrode combinations 130 of the orthogonal pair 142 can be aligned vertically with each other, and the outer electrodes of the electrode combinations 130 of the orthogonal pair 142 can be aligned vertically with each other. It should be noted that the scope of the present invention does not require that each electrode combination 130 has centerlines CL that coincide with each other. That is, the centerlines CL of the electrode combinations 130 on the first membrane 110 can be offset from the corresponding centerlines CL of the electrode combinations 130 on the second membrane 120. The orthogonal pair 142 includes two electrode combinations that at least partially overlap when the centerlines CL are offset from each other.

[0053] The end effector 100 may further include a flexible polymer layer 160 that encapsulates the membranes 110, 120 and the frame 150. The flexible polymer layer 160 may include openings such that the electrodes 131, 132 are exposed to the surrounding environment. In some examples, the flexible polymer layer 160 may include an outer surface having a thin portion that surrounds the electrode combination 130 and a thick portion that is approximately midpoint between the electrode combinations 130. This may improve the ability of the electrodes 130 to lie flatter against the target anatomy. Alternatively, the flexible polymer layer 160 may include an outer surface having a thicker portion that surrounds the electrode combination 130. In some examples, the frame 150 may be embedded in the flexible polymer layer 160 separately from the flexible circuits of the membranes 110, 120. This may increase the rigidity of the end effector 100. In some examples, the flexible polymer layer 160 may include a biocompatible silicone. In other examples, the flexible polymer layer 160 can include a biocompatible flexible polymer, a thermoelastic polymer material, and a dielectric material. The flexible polymer layer 160 can optionally be pigmented to facilitate laser cutting.

[0054] 6 is a cross-sectional view of an exemplary end effector having an additional structural member 155 around the periphery of the frame 150. The structural member 155 can be disposed around the periphery of the frame 150 between the flex circuits of the membranes 110, 120 to provide a planar surface for mounting the flex circuits. The structural member 155 can be selected from a group such as polymers, metals, semi-metals, rigid, elastic, or superelastic materials, and combinations thereof.

[0055] The end effector 100 can be further modified to include different geometries for the frame 150, different electrode arrangements, different geometries for the membranes 110, 120, as well as other suitable features and variations.

[0056] FIG. 7 is a diagram of an exemplary end effector 100 having an alternative electrode support structure. The end effector 100 includes a spine 190 that provides structural support for the electrode combination 130. The spine 190 may include a flexible tubular housing and a support frame extending through the flexible tubular housing. The support frame may provide structural support to the spine so that it expands into a predetermined configuration upon exiting the sheath catheter, similar to the structural function of the frame 150 (FIG. 3B). The tubular housing may have a variety of configurations. Wiring and other components may be disposed within the lumen of the tubular housing. For example, the tubular housing and components disposed therein may be configured similar to the spine disclosed in U.S. Patent Publication No. 2021 / 0369339, which is incorporated herein by reference and is attached in the appendix to priority patent application Ser. No. 63 / 507,154.

[0057] The electrode combination 130 can be attached to a spine 190, for example a membrane 110 that is secured to a polymeric tubular housing of the spine 190. The membrane 110 can include a flex circuit configured as disclosed in more detail elsewhere herein.

[0058] Each membrane 110 can include a longitudinal pair 141 of electrode combinations 130a, 130b. Each longitudinal pair 141 can be configured as a bipolar pair. Thus, the end effector 100 can include a plurality of bipolar pairs 141, each of which comprises a first electrode combination 130a and a second electrode combination 130b, where the first electrode combination 130a can include a first electrode and a second electrode configured as a sensing electrode and a reference electrode. The second electrode combination 130b can include a third electrode and a fourth electrode configured as a sensing electrode and a reference electrode. The reference electrode can be recessed perpendicular to the sensing electrode in the first electrode combination 130a and the second electrode combination 130b.

[0059] As shown in the inset of FIG. 7, the longitudinal pair 141 may include a first (outer) electrode having a first surface 133a, a second (inner) electrode having a second surface 134a, a third (outer) electrode having a third surface 133b, and a fourth (inner) electrode having a fourth surface 134b. The four electrodes are coupled to the same side of the end effector 100. The first electrode, and thus the first surface 133a, may be longitudinally aligned with the third electrode, and thus the third surface 133b. The second electrode, and thus the second surface 134a, may be longitudinally aligned with the fourth electrode, and thus the fourth surface 134b. The longitudinal pair 141 shown in FIG. 2 may be similarly configured as described in connection with FIG. 7.

[0060] Each of the first surface 133a and the third surface 133b is exposed to the surrounding environment and configured to contact tissue. The second surface 134a is surrounded by the first surface 133a. The fourth surface 134b is surrounded by the third surface 133b. The second surface 134a and the fourth surface 134b are each exposed to the surrounding environment.

[0061] The longitudinal pair 141 may include two electrode combinations, each having a sensing electrode and a reference electrode. The sensing electrodes may be aligned longitudinally. The reference electrodes may also be aligned longitudinally.

[0062] In one example, the second surface 134a is prevented from contacting tissue by a vertical gap H1 (FIG. 8A) between the second surface 134a and the first surface 133a. The fourth surface 134b is prevented from contacting tissue by a vertical gap H1 (FIG. 8A) between the third surface 133b and the fourth surface 134b. The vertical gap is measured along a first orthogonal axis O1. The third surface 133b is preferably coplanar with the first surface 133a. The first electrode and the third electrode may be configured to measure electrocardiogram signals as a bipolar pair.

[0063] In another example, the first surface 133a is prevented from contacting tissue by a vertical gap H2 (FIG. 8B) between the second surface 134a and the first surface 133a. The third surface 133b is prevented from contacting tissue by a vertical gap H2 (FIG. 8B) between the third surface 133b and the fourth surface 134b. The vertical gap is measured along a first orthogonal axis O1. The second surface 134a is preferably coplanar with the fourth surface 134b. The second electrode and the fourth electrode may be configured to measure electrocardiogram signals as a bipolar pair.

[0064] In another example, the longitudinal pair 141 includes two types of electrode combinations (FIGS. 8A and 8B) where the inner electrode is recessed into one of the electrode combinations and the outer electrode is recessed into the other electrode combination.

[0065] The electrode combinations 130 of the longitudinal pair 141 can be spaced apart from each other by a predetermined distance. The third surface 133b is spaced apart from the first surface 133a by a lateral gap L5 (as shown in FIG. 7), which is the shortest distance measured edge-to-edge from the first surface 133a to the third surface 133b. The electrode combinations 130 can be spaced apart from each other by a longitudinal distance L2 measured between the center points of each electrode combination 130, i.e., from the center point of the second surface 134a to the center point of the fourth surface 134b. The longitudinal pairs 141 can be spaced apart from each other by a longitudinal distance L3 measured from the center point or center of mass of the surface area of ​​the electrodes of each longitudinal pair 141. For example, the longitudinal distance L3 between the longitudinal pairs 141 can be measured from the center point between the electrode combinations 130 of the first longitudinal pair 141a to the center point between the electrode combinations 130 of the second longitudinal pair 141b, as shown.

[0066] The electrodes can be arranged in rows along the spine of the end effector 100b. The spine is separated by row spacing L4 such that the rows of electrodes are separated by row spacing L4.

[0067] Figures 8A, 8B, and 8C are cross-sectional views of an electrode combination 130. Figure 8A is a diagram of a first type of electrode combination 130 in which the second electrode 132 is recessed relative to the first electrode 131. Figure 8B is a diagram of a second type of electrode combination 130 in which the first electrode 131 is recessed relative to the second electrode 132. Figure 8C is a diagram of the first type of electrode combination 130 in which the second electrode 132 is recessed relative to the first electrode 131 and the first electrode 131 overhangs the second electrode 132 by an overhang length L6.

[0068] As shown in FIG. 8A, the membrane 110 can be shaped such that the recessed electrode is positioned in a recess 112 having an overhang, with the top perimeter 114 of the recess 112 overhanging the bottom perimeter 115 of the recess. If the geometry of the electrode combination 130 is circular as shown, the bottom perimeter 115 of the recess 112 can have a diameter D5 that is larger than the diameter D5 of the top perimeter 114. Thus, the bottom surface area of ​​the recess 112 can be larger than the top surface area of ​​the recess 112, with the bottom surface area defined as the surface area within the bottom perimeter 115 and the top surface area defined as the surface area with the top perimeter 114. Similarly, the membranes 110, 120 shown in FIGS. 4 and 6 may include such an overhang in the recess 112. Similarly, the electrode combination 130 as shown in FIG. 8B can be modified to include an overhang over the first electrode 131. Furthermore, a reference electrode having an alternative geometry can be positioned in an alternatively shaped recess having an overhang. The overhang can prevent the reference electrode from contacting tissue when the sensing electrode is in contact with tissue.

[0069] Alternatively, as shown in Figure 8B, the membrane 110 need not include an overhang over the recessed electrode. In this example, the recess 112 has a substantially uniform width D7 along the first orthogonal axis O1, and the second electrode 132 is disposed on a mesa having a substantially uniform width D6 along the first orthogonal axis O1.

[0070] Alternatively, as shown in FIG. 8C, the membrane 110 can be shaped such that the recessed electrode is placed in a recess 112 with an overhang, and the top perimeter 114 of the recess 112 overhangs the bottom perimeter 115 of the recess. The overhang can be such that the first electrode 131 overlaps the second electrode 132 by an overlap length L6. This configuration allows the contact area of ​​the first electrode 103 to be increased by increasing the width W1 of the first electrode without increasing the diameter D1 of the first electrode 131. The effective surface area 132 can remain approximately the same in both FIGS. 8A and 8C compared to a similar electrode combination design as shown in FIG. 8A, where the second electrode 132 has the same surface area of ​​the top surface 133.

[0071] 9 is a diagram of an exemplary membrane 110 having a flex circuit layout that can be used to support an electrode combination 130 of an exemplary end effector 100. As described in more detail herein, a flex circuit can include multiple layers and can include one or more patterned conductive layers 143. FIG. 9 shows the pattern of the conductive layers of the flex circuit. A longitudinal gap L2 between the electrode combination 130 of the first longitudinal pair 142a is shown. A longitudinal gap L3 between the first longitudinal pair 141a and the second longitudinal pair 141b is shown.

[0072] 10 is a flow diagram 200 of method steps that may be used to detect a cardiac signal. In block 202, a first electrode and a second electrode may be disposed on a generally planar member such that one of the first electrode and the second electrode is recessed relative to the other of the first electrode and the second electrode. The first electrode and the second electrode may comprise an electrode combination 130. In block 204, a far-field signal may be sensed using the recessed one of the first electrode and the second electrode. In block 206, a cardiac signal may be sensed using the other of the first electrode and the second electrode. In block 208, the far-field signal may be subtracted from the cardiac signal.

[0073] 11A and 11B show an exemplary magnetic sensor circuit of the end effector 100. The end effector 100 can include multiple inductive coils or loops 171, 172, 181, each having a respective axis perpendicular to the end effector 100 in a planar configuration. As shown, the end effector 100 includes a first inductive loop 181, a second inductive loop 171, and a third inductive loop 173. The first inductive loop 181 is disposed proximate to the distal end of the end effector 100. A majority of the second inductive loop 171 and a majority of the third inductive loop 172 are disposed proximally relative to the first inductive loop 181. The second inductive loop 171 and the third inductive loop 172 can be elongated along a longitudinal axis and positioned as mirror images of each other about the longitudinal axis. The first inductive loop 181 can be rectangular. The loops 171, 172, 181 may be coplanar with one another. The flexible polymer layer 160 may have layers removed inside the coils 171, 172, 181 to make the end effector 100 more flexible while maintaining the geometric integrity and sensing capabilities of the coils 171, 172, 181. The loops 171, 172, 181 may be used as magnetic position sensors, as described in more detail in connection with FIG. 1. The magnetic sensor circuit may include a first loop circuit 180 including a first loop 181 and a proximal trace conductor 182 configured to deliver an electrical signal sensed by the first loop 181 to the PIU 30 (FIG. 1). The magnetic sensor circuit may include a second loop circuit 170 including a second loop 171, a third loop 172, and a proximal trace conductor 173 configured to deliver an electrical signal sensed by the second and third loops 171, 172 to the PIU 30. The magnetic sensor circuitry may be included in a patterned conductor layer of the flex circuit of the first film 110 and / or the second film 120 .

[0074] Although exemplary embodiments of the subject matter included in the present invention have been shown and described, further adaptations of the methods and systems described herein may be achieved by appropriate modifications without departing from the scope of the claims. For example, the catheters disclosed in the references incorporated herein by reference and / or in the references attached in the appendix of priority patent application No. 63 / 507154 may be modified to include one or more electrode combinations 130 or arrangements thereof disclosed herein, as would be understood by one of ordinary skill in the art. Furthermore, where the above methods and steps show certain events occurring in a particular order, it is intended that the particular steps need not be performed in the order described, but may be performed in any order so long as the steps enable the embodiments to function for their intended purpose. Thus, to the extent there are variations of the invention that are within the spirit of the disclosure or equivalent to the invention found in the claims, this patent is intended to cover those variations as well. Some such modifications should be apparent to one of ordinary skill in the art. For example, the above examples, embodiments, geometries, materials, dimensions, proportions, steps, etc. are exemplary. Thus, the claims should not be limited to the specific details of structure and operation set forth in the specification and drawings.

[0075] The following clauses list non-limiting embodiments of the present disclosure. Clause 1. An end effector for a medical probe, comprising: a first electrode on a first side of the end effector, the first electrode having a first surface exposed to the surrounding environment and configured to contact tissue; and a second electrode on the first side of the end effector, the second electrode being at least partially surrounded by the first electrode, the second electrode including a second surface exposed to the surrounding environment, the second electrode being inhibited from contacting the tissue by a first vertical gap between the first and second surfaces.

[0076] Clause 2. An end effector for a medical probe comprising: a frame member extending along a longitudinal axis; and first and second electrodes arranged generally perpendicular to the longitudinal axis of the frame member, one of the first and second electrodes being recessed relative to the other of the first and second electrodes to prevent such recessed electrode from contacting tissue.

[0077] Clause 3. An end effector as described in clause 2, wherein the first electrode and the second electrode are disposed on a substrate spaced apart from the frame member and not in contact with the frame member.

[0078] Clause 4. The end effector of clause 3, wherein the frame member is encapsulated in a polymer to maintain a gap from the frame member to the first electrode and the second electrode.

[0079] Clause 5. An end effector according to any one of clauses 1 to 4, wherein the second electrode is completely surrounded by the first electrode.

[0080] Clause 6. An end effector described in any one of clauses 1 to 4, wherein the first electrode has a plurality of arcuate sections arranged around the second electrode, the plurality of arcuate sections being spaced apart from one another.

[0081] Clause 7. An end effector described in any one of clauses 1 to 6, wherein the first electrode has one of an annular shape or a divided ring and the second electrode has one of a circular shape or a polygonal shape.

[0082] Clause 8. The end effector of clause 7, wherein the first electrode has a first outer diameter of about 0.5 mm to about 0.67 mm.

[0083] Clause 9. The end effector of clause 7 or 8, wherein the second electrode has a second outer diameter of about 0.44 mm.

[0084] Clause 10. An end effector according to any one of clauses 1-9, wherein the first electrode has a first surface area approximately equal to a second surface area of ​​the second electrode.

[0085] Clause 11. The first electrode is about 0.15 mm 2 11. The end effector of any one of clauses 1-10, having a first surface area of.

[0086] Clause 12. The second electrode is about 0.15 mm 2 11. The end effector of any one of clauses 1-10, having a second surface area of.

[0087] Clause 13. An end effector described in any one of clauses 1 to 12, wherein the first surface is laterally spaced from the second surface by a first lateral gap region having a surface area approximately equal to the first surface area and / or the second surface area, the first lateral gap region being parallel to the first surface and parallel to the second surface and being a planar surface region between the first surface and the second surface.

[0088] Clause 14. An end effector described in any one of clauses 1 to 13, wherein the first surface is laterally spaced from the second surface by a first lateral gap region that is approximately equal to or less than the first surface area and approximately equal to or less than the second surface area, the first lateral gap region is parallel to the first surface, parallel to the second surface and is a planar surface region between the first and second surfaces, the first surface has an annular width that is greater than or equal to the annular width of the first lateral gap region, and the second surface has a diameter that is greater than or equal to the annular width of the first lateral gap region.

[0089] Clause 15. The end effector of clause 14, wherein an annular width of the first lateral gap region is approximately equal to 0.83 times the second surface area and / or 0.83 times the first surface area.

[0090] Clause 16. An end effector described in any one of clauses 1 to 15, wherein the first electrode is configured to measure an electrocardiogram signal from the tissue and the second electrode is configured to sense a long-distance signal.

[0091] Clause 17. An end effector according to any one of clauses 1 to 16, wherein the first surface and the second surface have planar surfaces.

[0092] Clause 18. An end effector described in any one of clauses 1 to 17, wherein the first surface and the second surface extend along the longitudinal axis and face perpendicular to the longitudinal axis.

[0093] Clause 19. An end effector described in any one of clauses 1 to 18, further comprising a first side including a recess, whereby a first electrode is coupled to the first side and surrounds the recess, and a second electrode is disposed within the recess.

[0094] Clause 20. The end effector of clause 19, wherein the second electrode is coupled to the first side at a bottom of the recess, the recess having a larger diameter at the bottom compared to the diameter at a top of the recess.

[0095] Clause 21. An end effector described in any one of clauses 1 to 20, further comprising: a third electrode coupled to a first side of the end effector, exposed to the surrounding environment, and including a third surface configured to contact tissue, wherein the third surface is coplanar with the first surface, the third surface being spaced from the first surface by a second lateral gap; and a fourth electrode coupled to the first side of the end effector and surrounded by the third electrode, the fourth electrode including a fourth surface exposed to the surrounding environment and inhibited from contacting tissue by a second vertical gap between the third surface and the fourth surface, the second vertical gap being measured substantially perpendicular to the third surface and perpendicular to the fourth surface.

[0096] Clause 22. The end effector described in clause 21, wherein the first electrode and the third electrode are configured to measure an electrocardiogram signal as a bipolar pair.

[0097] Clause 23. An end effector as described in clause 21 or 22, wherein the second surface is laterally spaced from the fourth surface by approximately 0.85 mm, measured from a centre point of the second surface to a centre point of the fourth surface.

[0098] Clause 24. An end effector described in any one of clauses 21 to 23, wherein the first electrode is longitudinally aligned with the third electrode and the second electrode is longitudinally aligned with the fourth electrode.

[0099] Clause 25. An end effector described in any one of clauses 21 to 24, further comprising a plurality of bipolar pairs, each of the bipolar pairs comprising a first electrode combination and a second electrode combination, the first electrode combination including a first electrode and a second electrode, the second electrode combination including a third electrode surrounding a fourth electrode, the fourth electrode being recessed perpendicular to the third electrode.

[0100] Clause 26. An end effector as described in clause 25, wherein the plurality of bipole pairs includes a second bipole pair spaced apart from the first bipole pair by approximately 2.4 mm, measured from a center point or center of mass of the surface area of ​​the first bipole pair and a center point or center of mass of the second bipole pair.

[0101] Clause 27. An end effector as described in clause 25 or 26, wherein the plurality of bipolar pairs includes between 6 and 24 bipolar pairs.

[0102] Clause 28. An end effector described in any one of clauses 1 to 27, further comprising: a fifth electrode coupled to a second side of the end effector facing away from the first side and having a fifth surface exposed to the ambient environment, the fifth surface being aligned perpendicular to the first surface of the first electrode; and a sixth electrode coupled to the second side, surrounded by the fifth electrode and exposed to the ambient environment, the sixth surface being exposed to the ambient environment and spaced apart by a third vertical gap between the fifth surface and the sixth surface, the third vertical gap being measured perpendicular to the fifth surface and perpendicular to the sixth surface.

[0103] Clause 29. The end effector of clause 28, wherein the fifth electrode is configured as a reference electrode relative to the first electrode.

[0104] Clause 30. An end effector according to any one of clauses 1 to 29, wherein the end effector is substantially planar along the longitudinal axis.

[0105] Clause 31. An end effector described in any one of clauses 1 to 30, further comprising a frame having one or more struts extending along a longitudinal axis, and a first membrane extending between the one or more struts on a first side of the end effector and exposed to the surrounding environment, wherein the first electrode and the second electrode are attached to the first membrane such that the second electrode is positioned within a recess in the first membrane.

[0106] Clause 32. An end effector as described in clause 31, further comprising a plurality of first electrode combinations attached to the first membrane and forming rows and columns of an electrode array, each electrode combination of the plurality of first electrode combinations comprising a respective first electrode having a respective first surface exposed to the ambient environment and configured to contact tissue, and a respective second electrode having a respective second surface exposed to the ambient environment and inhibited from contacting tissue by a respective first vertical gap between the respective first surface and the respective second surface, each first vertical gap being measured perpendicular to the respective first surface and perpendicular to the respective second surface.

[0107] Clause 33. An end effector as described in clause 32, comprising: a second membrane extending between one or more struts such that at least a portion of the frame is between the first membrane and the second membrane, the second membrane being exposed to the ambient environment; and a plurality of second electrode combinations attached to the second membrane such that each second electrode combination of the plurality of second electrode combinations is positioned substantially opposite a respective electrode combination of the plurality of first electrode combinations and spaced apart from one another, each electrode combination of the plurality of second electrode combinations including a respective first electrode exposed to the ambient environment and including a respective first surface configured to contact tissue, and a respective second electrode exposed to the ambient environment and including a respective second surface inhibited from contacting tissue by a respective first vertical gap between the respective first surface and the respective second surface, the respective first vertical gap being measured perpendicular to the respective first surface and perpendicular to the respective second surface.

[0108] Clause 34. An end effector as described in any one of clauses 1 to 33, wherein the end effector is configured to expand into a planar configuration, and the end effector further comprises a plurality of induction loops coupled to the end effector such that each induction loop of the plurality of induction loops has a respective axis perpendicular to the end effector in the planar configuration.

[0109] Clause 35. An end effector as described in Clause 34, wherein the multiple inductive loops include a first inductive loop, a second inductive loop, and a third inductive loop, the first inductive loop being positioned proximal to a distal end of the end effector, and a majority of the second inductive loop and a majority of the third inductive loop being positioned proximally relative to the first inductive loop.

[0110] Clause 36. The end effector of clause 35, wherein the second inductive loop is positioned in a mirror image of the third inductive loop.

[0111] Clause 37. A medical probe comprising: an elongate shaft extending along a longitudinal axis; an end effector coupled to a distal end of the elongate shaft; and a plurality of electrode combinations coupled to the end effector, each electrode combination of the plurality of electrode combinations comprising a respective inner electrode and a respective outer electrode disposed about at least a majority of the respective inner electrode and vertically offset from the respective inner electrode, each respective inner electrode and each respective outer electrode being exposed to an ambient environment.

[0112] Clause 38. A medical probe as described in clause 37, wherein each respective inner electrode is prevented from contacting tissue by each respective outer electrode being vertically offset from the respective inner electrode.

[0113] Clause 39. A medical probe as described in clause 37 or 38, wherein each of the respective first electrodes is configured to measure an electrocardiogram signal from tissue and each of the respective second electrodes is configured to sense a long-distance signal.

[0114] Clause 40. A medical probe described in any one of clauses 37 to 39, wherein the end effector comprises a bipolar pair comprising two electrode combinations of a plurality of electrode combinations, the bipolar pair being configured to detect a voltage difference between the outer electrodes of each of the two electrode combinations of the bipolar pair.

[0115] Clause 41. A method of reducing a long-range signal acquired for intracardiac mapping, the method comprising: arranging a first electrode and a second electrode on a generally planar member such that one of the first electrode and the second electrode is recessed relative to the other of the first electrode and the second electrode; sensing the long-range signal using the recessed one of the first electrode and the second electrode; sensing a cardiac signal using the other of the first electrode and the second electrode; and subtracting the long-range signal from the cardiac signal.

[0116] Clause 42. The method of clause 41, wherein the first electrode comprises a first surface area and the second electrode comprises a second surface area substantially equal to the first surface area.

[0117] Clause 43. The method of clause 41, wherein the first electrode at least partially surrounds the second electrode.

[0118] Although exemplary embodiments of the subject matter encompassed by the present invention have been shown and described, further adaptations of the methods and systems described herein can be achieved by appropriate modifications without departing from the scope of the claims. Moreover, where the above methods and steps show certain events occurring in a particular order, it is intended that the specific steps need not be performed in the order described, but rather in any order as long as the steps enable the embodiments to function for their intended purpose. Thus, to the extent there are variations of the invention that are within the spirit of the disclosure or equivalent to the invention found in the claims, this patent is intended to cover those variations as well. Some such modifications should be apparent to those skilled in the art. For example, the above examples, embodiments, geometries, materials, dimensions, proportions, steps, etc. are exemplary. Thus, the claims should not be limited to the specific details of structure and operation set forth in the specification and drawings.

[0119] [Embodiment] (1) An end effector for a medical probe, comprising: a frame member extending along a longitudinal axis; an end effector comprising: a first electrode and a second electrode arranged generally perpendicular to the longitudinal axis of the frame member, one of the first electrode and the second electrode being recessed relative to the other of the first electrode and the second electrode to prevent such recessed electrode from contacting tissue. (2) An end effector as described in embodiment 1, wherein the first electrode and the second electrode are disposed on a substrate spaced apart from the frame member and not in contact with the frame member. (3) An end effector as described in embodiment 2, wherein the frame member is encapsulated in a polymer to maintain a gap from the frame member to the first electrode and the second electrode. (4) An end effector as described in embodiment 1, wherein the second electrode is completely surrounded by the first electrode. (5) An end effector as described in embodiment 1, wherein the first electrode has a plurality of arcuate sections arranged around the second electrode, the plurality of arcuate sections being spaced apart from one another.

[0120] (6) An end effector as described in embodiment 1, wherein the first electrode has a first surface area approximately equal to a second surface area of ​​the second electrode. (7) An end effector as described in embodiment 1, wherein the first electrode is configured to measure an electrocardiogram signal from tissue and the second electrode is configured to sense a long-distance signal. (8) An end effector as described in embodiment 1, further comprising a first side including a recess, the first electrode being coupled to the first side and surrounding the recess, and the second electrode being disposed within the recess. (9) An end effector as described in embodiment 1, further comprising a plurality of bipolar pairs, each of the bipolar pairs including a first electrode combination and a second electrode combination, the first electrode combination including the first electrode and the second electrode, the second electrode combination including a third electrode surrounding a fourth electrode, and the fourth electrode being recessed perpendicular to the third electrode. (10) The end effector of embodiment 1, wherein the end effector is substantially planar along the longitudinal axis.

[0121] (11) A frame including one or more struts extending along a longitudinal axis; An end effector as described in embodiment 1, further comprising: a first membrane extending between the one or more pillars on a first side of the end effector and exposed to the surrounding environment, the first electrode and the second electrode being fixed to the first membrane such that the second electrode is positioned within a recess in the first membrane. (12) The end effector is configured to expand into a planar configuration, the end effector comprising: An end effector as described in embodiment 1, further comprising a plurality of inductive loops coupled to the end effector, each of the plurality of inductive loops having a respective axis perpendicular to the end effector in the planar configuration. (13) An end effector for a medical probe, comprising: a first electrode on a first side of the end effector, the first electrode having a first surface exposed to an ambient environment and configured to contact tissue; a second electrode on the first side of the end effector, the second electrode being at least partially surrounded by the first electrode and having a second surface exposed to the surrounding environment, the second surface being inhibited from contacting tissue by a first vertical gap between the first surface and the second surface. (14) An end effector as described in embodiment 13, wherein the first surface and the second surface include planar surfaces. (15) An end effector as described in embodiment 13, wherein the first surface and the second surface extend along a longitudinal axis and face perpendicular to the longitudinal axis.

[0122] (16) An end effector as described in embodiment 13, further comprising a frame member extending along a longitudinal axis, the first electrode and the second electrode being disposed on a substrate spaced apart from and not in contact with the frame member. (17) The end effector of embodiment 13, further comprising a first side including a recess, the first electrode being coupled to the first side and surrounding the recess, and the second electrode being disposed within the recess. (18) A third electrode coupled to a first side of the end effector, the third electrode having a third surface exposed to an ambient environment and configured to contact tissue, the third surface being coplanar with the first surface, the third surface being spaced from the first surface by a second lateral gap; An end effector as described in embodiment 13, further comprising: a fourth electrode coupled to the first side of the end effector and surrounded by the third electrode, the fourth electrode having a fourth surface exposed to the surrounding environment, the fourth surface being inhibited from contacting tissue by a second vertical gap between the third surface and the fourth surface, the second vertical gap being measured substantially perpendicular to the third surface and perpendicular to the fourth surface. (19) An end effector as described in embodiment 18, wherein the first electrode and the third electrode are configured to measure an electrocardiogram signal as a bipolar pair. (20) The end effector of embodiment 13, further comprising a plurality of bipolar pairs, each of the bipolar pairs including a first electrode combination and a second electrode combination, the first electrode combination including the first electrode and the second electrode, the second electrode combination including a third electrode surrounding a fourth electrode, the fourth electrode being recessed perpendicular to the third electrode.

Claims

1. 1. An end effector for a medical probe, comprising: a frame member extending along a longitudinal axis; and a first electrode and a second electrode disposed generally perpendicular to the longitudinal axis of the frame member, one of the first electrode and the second electrode being recessed relative to the other of the first electrode and the second electrode to prevent such recessed electrode from contacting tissue.

2. The end effector of claim 1 , wherein the first electrode and the second electrode are disposed on a substrate spaced apart from and out of contact with the frame member.

3. The end effector of claim 2 , wherein the frame member is encapsulated in a polymer to maintain a gap from the frame member to the first electrode and the second electrode.

4. The end effector of claim 1 , wherein the second electrode is completely surrounded by the first electrode.

5. The end effector of claim 1 , wherein the first electrode comprises a plurality of arcuate sections disposed about the second electrode, the plurality of arcuate sections being spaced apart from one another.

6. The end effector of claim 1 , wherein the first electrode comprises a first surface area approximately equal to a second surface area of ​​the second electrode.

7. The end effector of claim 1 , wherein the first electrode is configured to measure electrocardiogram signals from tissue and the second electrode is configured to sense far-field signals.

8. 2. The end effector of claim 1, further comprising a first side including a recess, the first electrode coupled to the first side and surrounding the recess, and the second electrode disposed within the recess.

9. 2. The end effector of claim 1, further comprising a plurality of bipolar pairs, each of the bipolar pairs including a first electrode combination and a second electrode combination, the first electrode combination including the first electrode and the second electrode, the second electrode combination including a third electrode surrounding a fourth electrode, the fourth electrode being recessed perpendicular to the third electrode.

10. The end effector of claim 1 , wherein the end effector is substantially planar along a longitudinal axis.

11. a frame including one or more struts extending along a longitudinal axis; 2. The end effector of claim 1, further comprising: a first membrane extending between the one or more posts on a first side of the end effector and exposed to an ambient environment, the first electrode and the second electrode being secured to the first membrane such that the second electrode is disposed within a recess in the first membrane.

12. The end effector is configured to expand into a planar configuration, the end effector comprising: The end effector of claim 1 , further comprising a plurality of inductive loops coupled to the end effector, each inductive loop of the plurality of inductive loops having a respective axis perpendicular to the end effector in the planar configuration.

13. 1. An end effector for a medical probe, comprising: a first electrode on a first side of the end effector, the first electrode comprising a first surface exposed to an ambient environment and configured to contact tissue; a second electrode on the first side of the end effector, the second electrode being at least partially surrounded by the first electrode and having a second surface exposed to the surrounding environment, the second surface being inhibited from contacting tissue by a first vertical gap between the first surface and the second surface.

14. The end effector of claim 13 , wherein the first surface and the second surface comprise planar surfaces.

15. The end effector of claim 13 , wherein the first surface and the second surface extend along a longitudinal axis and face perpendicular to the longitudinal axis.

16. 14. The end effector of claim 13, further comprising a frame member extending along a longitudinal axis, the first electrode and the second electrode being disposed on a substrate spaced apart from and out of contact with the frame member.

17. 14. The end effector of claim 13, further comprising a first side including a recess, the first electrode coupled to the first side and surrounding the recess, and the second electrode disposed within the recess.

18. a third electrode coupled to a first side of the end effector, the third electrode having a third surface exposed to an ambient environment and configured to contact tissue, the third surface being coplanar with the first surface, the third surface being spaced from the first surface by a second lateral gap; 14. The end effector of claim 13, further comprising: a fourth electrode coupled to the first side of the end effector and surrounded by the third electrode, the fourth electrode having a fourth surface exposed to the surrounding environment, the fourth surface being inhibited from contacting tissue by a second vertical gap between the third surface and the fourth surface, the second vertical gap being measured substantially perpendicular to the third surface and perpendicular to the fourth surface.

19. The end effector of claim 18 , wherein the first electrode and the third electrode are configured to measure an electrocardiogram signal as a bipolar pair.

20. 14. The end effector of claim 13, further comprising a plurality of bipolar pairs, each of the bipolar pairs including a first electrode combination and a second electrode combination, the first electrode combination including the first electrode and the second electrode, the second electrode combination including a third electrode surrounding a fourth electrode, the fourth electrode being recessed perpendicular to the third electrode.

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