Force sensing medical device

Abstract

Structures and methods for preventing electromagnetic (EM) interference from affecting a force indication from a force sensing medical device are disclosed. In one embodiment, a force sensing medical device includes one or more force sensor units that generate an indication of a force acting on the device. EM interference to the indication is minimized by using one or more ground paths, a conductive shield, or both. The ground path includes one or more electrically conductive mechanical actuator structures and traces in the force sensing indication signal cable. The circuit board is configured to prevent EM interference between the circuit board and the force sensor element. When a surgeon operates a force sensing medical device in a telesurgical system, reliability of force feedback to the surgeon during application of electrosurgical energy is enhanced.

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of priority and the filing date of U.S. Provisional Patent Application No. 63 / 425,524, entitled "FORCE SENSING MEDICAL INSTRUMENT", filed on November 15, 2022, the disclosure of which is incorporated herein by reference in its entirety. Background of the Invention

[0003] The embodiments described herein relate to force sensing technology, and more particularly, to force sensing technology suitable for use with a remotely operated surgical system. More specifically, the embodiments described herein relate to a force sensing medical instrument for determining the force applied to a medical device to control a surgical system that may provide force feedback to a system operator. More specifically, the embodiments described herein relate to the mitigation of electromagnetic interference when the force sensing medical instrument is exposed to an electric field.

[0004] Known techniques for minimally invasive surgery (MIS) employ instruments that can be manually controlled or controlled via a remotely operated medical system ("remote surgical system") that is handheld or mechanically grounded and operates at least partially under computer assistance. Many known MIS instruments include a treatment or diagnostic end - effector (e.g., forceps, cutting tool, or cautery tool) mounted on an optional wrist mechanism at the distal end of a shaft. During an MIS procedure, the end - effector, wrist mechanism, and distal end of the shaft are typically inserted through a small incision or natural body cavity of the patient via a cannula to position the end - effector at a working site within the patient. The optional wrist mechanism can be used to change the position and orientation of the end - effector relative to the shaft to perform a desired procedure at the working site. In known instruments, the movement of the instrument as a whole provides mechanical degrees of freedom (DOF) for the movement of the end - effector, and the wrist mechanism typically provides the desired DOF for the movement of the end - effector relative to the shaft of the instrument. For example, for forceps or other grasping tools, known wrist mechanisms can change the pitch and yaw of the end - effector relative to the shaft. The wrist may optionally provide a roll DOF for the end - effector, or the roll DOF may be achieved by rolling the shaft. The end - effector may optionally have additional mechanical DOF, such as clamping or blade movement. In some cases, the wrist and end - effector mechanical DOFs can be combined. For example, U.S. Patent No. 5,792,135 (filed on May 16, 1997) discloses a mechanism in which the wrist and end - effector clamping DOFs are combined.

[0005] Force-sensing medical devices are known and, together with associated remote surgical systems, can deliver haptic feedback to a surgeon performing a MIS procedure during the procedure. The haptic feedback can increase the surgeon's sense of immersion, realism, and intuitiveness when performing the procedure. For effective haptic rendering and accuracy, force sensors can be placed on the medical device and as close as possible to the anatomical tissue interaction. One approach is to include a force sensor unit having an electrical sensor element (e.g., strain gauge) at the distal end of the medical device shaft to measure the strain applied to the medical device. The measured strain can be used to determine the force applied to the medical device and as an input on which desired haptic feedback can be generated.

[0006] In some MIS procedures, an electric current is introduced into the surgical site, such as during electro-surgery. Electro-surgery broadly refers to a class of medical procedures that rely on applying high-frequency electrical energy (usually radio-frequency energy) to patient tissue to achieve a variety of possible effects, such as cutting, coagulation, necrosis, etc. For example, in some MIS procedures, tissue within a patient must be cauterized and transected. To perform such a procedure, an end effector clamp configured to apply bipolar or monopolar cautery energy is introduced into the surgical site to engage the target tissue, and electrical energy (e.g., radio-frequency energy) is delivered to the clamp to cauterize the engaged tissue. Alternatively, in some cases, it is known for a surgeon to engage tissue with a conductive end effector clamp that is not specifically configured to apply electrical energy and then place an actively charged electrode (e.g., a charged end effector on a second instrument) in conductive contact with the clamp (i.e., direct electrical coupling) in order to apply electro-surgical energy to the tissue.

[0007] The force-sensing instrument can be specifically designed to apply electro-surgical energy (e.g., bipolar forceps instrument) or not designed to apply electro-surgical energy (e.g., Cadiere forceps instrument). Regardless of whether the force-sensing medical device is designed to apply electro-surgical energy, during certain MIS procedures, the force-sensing medical device can be exposed to an electric field during an electro-surgical operation. And regardless of the method used to apply electro-surgical energy to the tissue, whether using an instrument specifically designed to apply electro-surgical energy or an instrument not specifically designed to apply electro-surgical energy, the current associated with the electro-surgical energy can be conducted through various components of the force-sensing medical device.

[0008] Exposure of a force-sensing medical device to an electric field can cause electromagnetic interference to be generated within the device, which can affect signals from a force sensor unit of the force-sensing device. Further, such an effect on the signals can result in an inaccurate indication of the force acting on the force-sensing medical device and an inaccurate associated tactile feedback to a surgeon operating the force-sensing device. Insofar as the tactile feedback is based on an indication of the force on the device, it is desirable to mitigate the effects of electromagnetic interference. Such mitigation is subject to the design of the force-sensing device itself and design constraints (e.g., the component materials required for strength or other mechanical properties, the small component size required for surgery, etc.).

[0009] The magnitude of the electromagnetic interference and / or the effect on the output of the force sensor unit can depend at least in part on the positioning of the various components of the force-sensing medical device. For example, in a force-sensing medical device specifically designed to apply electrosurgical energy to tissue, an energized end effector component can generate current in one or more other electrically conductive device components (e.g., metal components such as beams, mechanical cables, and / or shafts) that are spaced apart from the energized end effector component (e.g., by insulation or an insulation gap). Similarly, using a medical device specifically designed to apply electrosurgical energy near or in contact with a force-sensing medical device can generate current in one or more conductive components of the force-sensing medical device (e.g., metal components such as beams, mechanical cables, and / or shafts).

[0010] The conductive components of the force-sensing device (components dedicated to performing the force-sensing function (e.g., strain sensors, strain gauges, and / or sensor cables) or conductive components having a structural function) can be physically separated from each other by electrical insulation or a space gap. However, when current in a first component generates current in a second component across the insulation or gap between the two components, the two conductive components can become capacitively or inductively coupled (i.e., indirectly electrically coupled). The magnitude of the generated current is affected at least in part by the positioning of the two conductive components and the dielectric quality of the insulation or gap between them. For example, a strain sensor can be mechanically coupled to a conductive structure by an electrically insulating adhesive. According to the principle of capacitive coupling, current conducted by the structure can generate current in the strain sensor through the electrically insulating adhesive. The magnitude of the generated current can be affected by the distance between the strain sensor and the structure and other factors, the distance being determined by the thickness of the electrically insulating adhesive. Insofar as relatively low voltage variations in the strain sensor can indicate the force acting on the force-sensing medical device, the presence of electromagnetic interference (in the form of the generated current) in the output of the strain sensor can distort the force indication.

[0011] In addition to problems that may be caused by capacitive coupling, electromagnetic interference may also be generated by inductive coupling (e.g., antenna coupling or magnetic field coupling) between various components of a force-sensing medical device. When inductively coupled, a magnetic field generated by a current in one conductive component generates a current in a second conductive component. For example, a current may be generated via inductive coupling in a strain sensor and / or a portion of a sensor cable that carries a signal from the strain sensor. The presence of the current generated by inductive coupling is electromagnetic interference, which can distort the strain indication generated by the force sensor unit, thereby causing distortion of the indication of the force acting on the force-sensing medical device.

[0012] In some force-sensing medical devices, a distal force sensor unit is used to measure forces applied to the end effector of the medical device in the lateral direction (orthogonal to the long axis of the instrument axis; e.g., the X and Y directions in a Cartesian system), and a proximal force sensor unit is used to measure forces applied to the end effector in the axial direction (parallel to the long axis of the instrument axis; the Z direction in a Cartesian system). That is, the force-sensing units may be located at the distal end, proximal end, or both ends of the force-sensing medical device. The proximal portion of the medical device may include a circuit board that includes components of the force-sensing system, and the proximal force sensor unit is coupled to the circuit board. The circuit board and the components of the proximal force sensor unit are vulnerable to currents induced by inductive or capacitive coupling, which can distort the electrical signals generated by the proximal force sensor unit. Such inductive or capacitive coupling may be generated by these two components themselves, or may be generated by other instrument components (such as a conductive mechanical control cable, a conductive pulley over which the cable is routed, or a conductive mechanical structure that supports the pulley). Therefore, it is necessary to prevent electromagnetic interference, which can distort the indication of the force acting on the force-sensing medical device generated by the proximal force sensor unit.

[0013] In view of the foregoing, it is desirable to continuously seek new and improved systems and methods for controlling a surgical system based on an accurate measurement of the strain applied to a medical device by a force acting on the medical device and communicating an accurate associated tactile feedback sensation to a surgeon operating the medical device. SUMMARY OF THE INVENTION

[0014] This Summary of the Invention introduces certain aspects of the embodiments described herein to provide a basic understanding. This Summary of the Invention is not an extensive overview of the subject matter of the invention and is not intended to identify key or important elements or to delineate the scope of the subject matter of the invention.

[0015] This document describes structures and methods for preventing electromagnetic (EM) interference from affecting force indication from a force-sensing medical device. The force-sensing medical device includes one or more force sensor units that generate an indication of a force acting on the device. For example, a medical device as described herein can include a distal force sensor unit, a proximal force sensor unit, or both a distal force sensor unit and a proximal force sensor unit. The EM interference to the indication is minimized by using one or more ground paths, conductive shields, or both. The ground path includes one or more conductive mechanical actuator structures and traces in a force-sensing indication signal cable. The electronic circuit board is configured to prevent EM interference between the electronic circuit board and the force sensor elements of one or both of the force sensor units. Thus, when a surgeon operates the force-sensing medical device in a remote surgery system, the reliability of force feedback to the surgeon during application of electrosurgical energy is enhanced.

[0016] In some embodiments, a medical device includes a shaft that includes a proximal portion and a distal portion. A tool is movably coupled to the distal portion of the shaft, and a distal force sensor unit is coupled to the distal portion of the shaft and is configured to sense a force on the tool. A proximal mechanical structure is coupled to the proximal portion of the shaft, and an electronic circuit board is coupled to the proximal mechanical structure. A drive element is coupled between the tool and the proximal mechanical structure, and actuation of the drive element causes movement of the tool. An electrical ground path is defined between the distal force sensor unit and the electronic circuit board, and the electrical ground path includes the drive element.

[0017] In some embodiments, the proximal mechanical structure includes a proximal pulley and a pulley cover that at least partially covers the pulley. The drive element is in electrical contact with the pulley, the pulley is in electrical contact with the pulley cover, the pulley cover is in electrical contact with the electronic circuit board, and the ground path includes the pulley and the pulley cover.

[0018] In some embodiments, the medical device further includes at least one of an O-ring, a gasket, and a plated component coupled between the electronic circuit board and the proximal mechanical structure. In some embodiments, the tool includes a tool pulley, and the drive element is electrically coupled to the tool pulley.

[0019] In some embodiments, the ground path is a first ground path, and the medical device further includes a sensor signal cable electrically coupled between the distal force sensor unit and the electronic circuit board. A second electrical ground path is defined between the distal force sensor unit and the electronic circuit board, and the second ground path includes the sensor signal cable. In some embodiments, the medical device further includes a proximal force sensor unit coupled to the electronic circuit board, and the proximal force sensor unit is configured to determine a force applied to the tool in a direction along the length of the shaft. In some embodiments, the tool is electrically insulated from the force sensor unit. In some embodiments, the tool is in electrical contact with the ground path.

[0020] In some embodiments, the electronic circuit board includes a first layer and a second layer. The first layer includes a plurality of conductive traces, and the second layer includes a conductive material. The conductive material of the second layer is electrically coupled to the electrical ground path. In some embodiments, the medical device is configured as an instrument in a remote surgical system.

[0021] In some embodiments, a medical device includes: a proximal mechanical structure; and an electronic circuit board coupled to the proximal mechanical structure, and the electronic circuit board includes a plurality of conductive traces. An electrically grounded conductive shield is positioned distally below the plurality of conductive traces. A force sensor unit including a sensor element is positioned proximally above the conductive traces. There is a physical electrical connection between the sensor element and one or more of the plurality of conductive traces, and there is no physical electrical connection between the sensor element and the conductive shield.

[0022] In some embodiments, the medical device further includes a second sensor element. There is a physical electrical connection between the second sensor element and one or more of the plurality of conductive traces, and there is no physical electrical connection between the second sensor element and the conductive shield. The sensor element and the second sensor element are each spaced an equal distance from the conductive shield. In some embodiments, the sensor element is an inductive coil sensor element.

[0023] In some embodiments, the conductive shield includes a gap positioned to prevent inductive coupling between the conductive shield and the sensor element. In some embodiments, the electronic circuit board includes a first layer and a second layer positioned distally below the first layer; the first layer includes conductive traces, the second layer includes a conductive shield, and a portion of the first layer extends proximally above the gap.

[0024] In some embodiments, the medical device further includes a shaft coupled to the proximal mechanical structure. The shaft is operably coupled to the force sensor unit such that translational movement of the shaft causes translational movement of a portion of the force sensor unit relative to the electronic circuit board.

[0025] In some embodiments, the electronic circuit board includes an opening and an outer edge, and a conductive shield surrounds the opening of the electronic circuit board. A gap is defined in the conductive shield between the opening of the electronic circuit board and the outer edge of the electronic circuit board. In some embodiments, the medical device includes an electrical ground, and one or more of the plurality of conductive traces are electrically connected to the electrical ground.

[0026] In some embodiments, the medical device further includes a shaft, a tool, and a distal force sensor unit. The shaft includes a proximal portion and a distal portion. The proximal portion of the shaft is coupled to the proximal mechanical structure and the tool, and the distal force sensors are each coupled to the distal portion of the shaft. In some embodiments, the tool is electrically insulated from the distal force sensor unit. In some embodiments, the medical device further includes a drive element operably coupled between the tool and the proximal mechanical structure such that actuation of the drive element causes movement of the tool. The drive element defines a portion of an electrical ground path between the distal force sensor unit and the electrical ground, or between the tool and the electrical ground, or between both the distal force sensor unit and the tool and the electrical ground.

[0027] In some embodiments, the medical device further includes a sensor signal cable electrically coupled between the distal force sensor unit and the electronic circuit board. The sensor signal cable includes an electrical ground trace, and the electrical ground trace of the sensor signal cable defines a portion of the ground path between the distal force sensor unit and the electrical ground.

[0028] In some embodiments, the electronic circuit board includes a first layer and a second layer positioned distally below the first layer. The first layer includes conductive traces, and the second layer includes a conductive shield positioned distally below the conductive traces. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a plan view of a minimally invasive teleoperated surgical system for performing a medical procedure such as surgery according to an embodiment.

[0030] Figure 2 is Figure 1 a perspective view of an optional auxiliary unit of the minimally invasive teleoperated surgical system shown.

[0031] Figure 3 is Figure 1 a perspective view of a user console of the minimally invasive teleoperated surgical system shown.

[0032] Figure 4 is Figure 1 a front view of a manipulator unit of the minimally invasive teleoperated surgical system shown including a plurality of instruments.

[0033] Figure 5Schematic illustration of a medical device according to an embodiment, showing a ground path GP.

[0034] Figure 6 Schematic illustration of a portion of a medical device according to an embodiment, including a circuit board coupled to a proximal mechanical structure.

[0035] Figure 7 Perspective view of a medical device according to an embodiment.

[0036] Figure 8 Is Figure 7 An enlarged perspective view of the distal portion of the medical device.

[0037] Figure 9 Is Figure 7 An enlarged view of the proximal mechanical structure of the medical device, with selected components removed for illustrative purposes.

[0038] Figure 10 Is Figure 9 A side view of the proximal mechanical structure.

[0039] Figure 11 Is Figure 10 Of Figure 10 An enlarged side view of a portion of the proximal mechanical structure in frame B.

[0040] Figure 12A Is a flowchart showing example components included in the ground path of the medical device in Figure 7 The medical device.

[0041] Figure 12B Is Figure 7 A side view of the medical device, showing the ground path extending between the end effector and the proximal force sensor unit.

[0042] Figure 13A Is Figure 7 A perspective view of the electronic circuit board and the proximal force sensor unit of the medical device.

[0043] Figure 13B Is Figure 13A A partial exploded view of the proximal force sensor unit and the electronic circuit board.

[0044] Figure 14A Is Figure 13A An enlarged perspective view of a portion of the proximal force sensor unit and the electronic circuit board.

[0045] Figure 14B Is Figure 14A A top view of a portion of the proximal force sensor unit and the electronic circuit board.

[0046] Figure 14C IsFigure 14A Side view of a proximal force sensor unit and a portion of an electronic circuit board.

[0047] Figure 15 is Figure 7 Top view of an electronic circuit board of a medical device.

[0048] Figure 16 is Figure 15 Top view of an electronic circuit board with the top layer removed.

[0049] Figure 17 is Figure 13A Bottom perspective view of an electronic circuit board with a sensor signal cable attached to the electronic circuit board.

[0050] Figure 18 Diagrammatic illustration of a portion of a proximal force sensor unit according to an embodiment. Detailed Description

[0051] The embodiments described herein can be advantageously used in various force sensor applications, such as for grasping, cutting, and manipulation operations associated with minimally invasive surgery. The embodiments described herein can also be used in various non-medical applications, such as for example, remote operating systems for search and rescue, remotely controlled diving devices, aerial devices, automobiles, etc. The medical device or apparatus of the present application enables movement in three or more degrees of freedom (DOF). For example, in some embodiments, the end effector of the medical device can move relative to the body of the instrument in three mechanical DOFs (e.g., pitch, yaw, and roll (axial roll)). There can also be one or more mechanical DOFs within the end effector itself, for example, two jaws (2 DOFs) each rotating relative to a U-shaped clamp and a distal U-shaped clamp rotating relative to the proximal U-shaped clamp (one DOF). Thus, in some embodiments, the medical device or apparatus of the present application enables movement in six DOFs. The embodiments described herein can also be used to determine the force applied (or exerted) on the distal portion of the instrument during use.

[0052] Generally, the present disclosure relates to systems and methods for controlling a surgical system (system), such as a minimally invasive teleoperated surgical system. In particular, the present disclosure includes a force sensing system that can include a proximal force sensor unit and a distal force sensor unit configured to mitigate electromagnetic interference. The force sensor units can be used with a force sensing medical device (instrument) to provide an indication of the force affecting the instrument. This indication of the force can be used by the system to deliver haptic feedback to a user control unit of the system.

[0053] The distal force sensor unit may include a strain sensor coupled to an elastically deformable beam. The beam is configured to deform in response to a load acting at the distal portion of the instrument. The strain sensor includes a strain gauge that measures the strain generated in the beam due to deflection. In some embodiments, a sensor signal cable may be coupled to the distal force sensor unit, extend proximally, and be coupled to an electronic circuit board of the medical device. The sensor signal cable carries the strain signal to the electronic circuit board. Additional details regarding the sensor signal cable are provided in U.S. Provisional Patent Application No. 63 / 425,520, filed on November 15, 2022, the disclosure of which is incorporated herein by reference. The strain sensor indicates the strain magnitude in the form of a relatively small voltage difference. In some embodiments, the strain gauges are arranged in a Wheatstone bridge configuration, where one half of the Wheatstone bridge is configured to carry a signal (“positive”) from one location on the beam and the other half is configured to carry a signal (“negative”) from a different location on the beam. Instead of an absolute voltage, the voltage difference between the signal carried by the positive trace and the signal carried by the negative trace indicates the strain magnitude measured in the absence of electromagnetic interference.

[0054] During certain procedures, the distal force sensor unit may be exposed to an electric field. Such exposure may result in the development of electromagnetic interference, which can affect the signals in the positive and / or negative traces. For example, a current conducted through a portion of the distal force sensor unit, such as the beam, may induce an unintended current in another portion of the distal force sensor unit. The induced current may be generated by capacitive coupling and / or inductive coupling between various conductive components of the distal force sensor unit. The magnitude of the induced current and thus the magnitude of the electromagnetic interference may be affected by the position and / or orientation of the various conductive components of the distal force sensor unit relative to each other. When the magnitude of the electromagnetic interference (i.e., the generated current) in one of the traces is greater than the magnitude of the electromagnetic interference in the other trace, the voltage difference is distorted and thus the measured strain magnitude is distorted. However, when the difference between the magnitudes of the electromagnetic interference in each of the traces is minimized, the effect of the electromagnetic interference in one trace is substantially canceled by the electromagnetic interference in the other trace, and vice versa. Thus, it is desirable to mitigate the effect of electromagnetic interference by minimizing the difference between the induced current in the positive trace coupled to one half of the Wheatstone bridge and the corresponding induced current in the negative trace coupled to the other half of the Wheatstone bridge. Additional details regarding such embodiments are described in U.S. Provisional Application No. 63 / 425,518, filed on November 15, 2022, the disclosure of which is incorporated herein by reference.

[0055] In some operations, exposure to an electric field may cause a current to be conducted by the beam. This current can induce a current in a strain sensor component that is mechanically coupled to the beam via a capacitor through capacitive coupling. However, the distance between each of the components in the strain sensor and the beam can vary, for example, based on variations in the thickness of the adhesive used to couple the component to the beam. This variation in the distance between the components in the beam results in a capacitively induced current of varying magnitude within the strain sensor. Thus, in some embodiments, the distal force sensor unit described herein is configured to reduce or eliminate variations in the magnitude of the induced current. The distal force sensor unit utilizes a conductive layer positioned between the beam and the strain sensor, with an electrically insulating layer positioned between the conductive layer and the strain sensor. Thus, the insulating layer can have a uniform thickness, and the conductive layer can have a flatness within a specific flatness tolerance. The uniform thickness and / or flatness can establish the strain sensor at a uniform separation distance from the conductive layer. The conductive layer is electrically coupled to the beam such that the current conducted by the beam is also conducted by the conductive layer. Thus, the magnitude of the capacitively induced current in the various components (e.g., strain gauges) of the strain sensor is determined by the uniform distance between the strain sensor and the conductive element, rather than by the variable distance between the strain sensor components and the beam. Since the strain sensor and the conductive layer have a uniform separation distance, the induced current introduced to the positive trace is substantially equal to the induced current introduced to the corresponding negative trace, thereby canceling the effects of electromagnetic interference.

[0056] In some operations, exposure to an electric field may cause electromagnetic interference (EMI) resulting from inductive coupling between the various components of the strain sensor. To mitigate the effects of inductive coupling, the strain sensor can be configured to maximize longitudinal symmetry and transverse symmetry. The symmetry of the strain sensor helps to cancel out the various inductively induced currents and, thus, the effects of electromagnetic interference. For example, as described herein, the strain sensor can include a first region adjacent to a first strain gauge and a second region adjacent to a second strain gauge.

[0057] The medical device described herein includes a proximal force sensor unit that includes a compact inductive force sensor to measure the force applied to the end effector of the medical device in the axial direction (parallel to the long axis of the device axis; the Z direction in the Cartesian coordinate system). As described herein, two inductive coils are each wound around a polymer cylinder, and magnets (e.g., ferrite beads, EMI suppression beads, nickel-zinc beads, etc.; the term "magnet" as used herein will be described in more detail below) held by a rod are movably positioned within each of the coils. When the magnets move axially within their respective coils, the inductance at each coil changes. The change in inductance at each of the coils can be used to measure the change in the position of the device axis, which can be used to determine the z-axis force measurement. The inductive force sensor described herein provides redundancy in force measurement by using two inductive coils positioned side by side. This arrangement also reduces the overall height of the force sensor, thus saving space within the proximal mechanical structure. Such an embodiment is described in more detail in International PCT Application No. PCT / US2021 / 049792, filed on September 10, 2021, the disclosure of which is incorporated herein by reference.

[0058] As described above, when the medical device is an electrosurgical type device (e.g., a cautery device) that provides electrical energy, there is typically an insulator between the cable drive pulley on the instrument tool (e.g., a clamp) and the portion of the tool that is exposed to the electrical energy. The presence of the insulator causes the components between the end effector, the distal force sensor unit, and the cable to be at a relatively low voltage. In the case where the medical device is a non-cautery type instrument and there is no insulator between the cable drive pulley on the instrument tool and the end effector, but the end effector is still energized by electrical energy, the cable drive pulley, the distal force sensor unit, and the circuit board ground plane of the instrument can all be at a relatively high voltage. For example, the tool can be energized by contact with another power source or medical device. Therefore, a ground path GP is provided between the electronic circuit board and the tool of the end effector to accommodate this relatively high voltage. The drive element is electrically connected to the electronic circuit board through a proximal pulley (which can act as an idler pulley) and a grounding screw to keep the drive element, the drive pulley, and the distal force sensor unit all at the same ground voltage. In some embodiments, the ground plane of the electronic circuit board can include a conductive layer that serves as a conductive shield for electrical grounding. In an alternative embodiment, the conductive shield can be a separate conductive component that is positioned to serve as a conductive shield for electrical grounding. Thus, the force sensing signal from the distal force sensor unit can be isolated from the energy caused by cautery or other electrical energy applied to the end effector.

[0059] As described herein, in some embodiments, a conductive layer of an electronic circuit board extends beneath or distal to an inductive coil force sensor. The inductive coil force sensor is positioned relative to the conductive layer such that the proximity and spatial uniformity of capacitive coupling between the sensor and the conductive layer in the electronic circuit board is maintained, which limits the likelihood of eddy currents from the sensor creating spatial non-uniformities in the potential of the electronic circuit board, which capacitively couples the sensor to a ground plane, and ensures that two sensors are equally affected. Thus, a uniform separation distance in multiple directions is established between the inductive force sensor and the conductive layer of the electronic circuit board. In some embodiments, a gap defined in the conductive layer of the electronic circuit board is provided to limit the likelihood of eddy currents in the inductive coil sensor creating spatial non-uniformities in the potential of the electronic circuit board. In such embodiments, the conductive layer (i.e., the ground plane) spans the entire circuit board and is partitioned around the inductive coil sensor to protect the ground path defined between the distal force sensor beam and the circuit board from the magnetic field caused by the inductive coil sensor.

[0060] As used herein, the term "about" when used in conjunction with a recited numerical indication means the recited numerical indication plus or minus up to 10% of the recited numerical indication. For example, the language "about 50" encompasses the range from 45 to 55. Similarly, the language "about 5" encompasses the range from 4.5 to 5.5.

[0061] The term "flexible" associated with a portion such as a mechanical structure, component, or component assembly should be interpreted broadly. In essence, the term means that the portion can be repeatedly bent and return to its original shape without damaging the portion. Certain flexible components can also be elastic. For example, a component (e.g., a flexure) is considered elastic if it has the ability to absorb energy during elastic deformation and then release the stored energy when unloaded (i.e., returned to its original state). Many "rigid" objects have a slight inherent elastic "bendability" due to material properties, although such objects are not considered "flexible" as the term is used herein.

[0062] As used in this specification and the appended claims, the word "distal" refers to the direction toward the working portion, and the word "proximal" refers to the direction away from the working portion. Thus, for example, the end of a tool closest to the target tissue will be the distal end of the tool, and the end opposite the distal end (i.e., the end manipulated by the user or coupled to an actuating shaft) will be the proximal end of the tool.

[0063] In addition, specific words chosen to describe one or more embodiments and optional elements or features are not intended to limit the invention. For example, spatial relative terms - such as "below", "beneath", "under", "above", "over", "proximal", "distal", etc. - may be used to describe the relationship of one element or feature to another as shown in the figures. These spatial relative terms are intended to cover different positions (i.e., translational placement) and orientations (i.e., rotational placement) of the device during use or operation in addition to the positions and orientations shown in the figures. For example, if the device in the figures is flipped, an element described as "below" or "beneath" other elements or features will be "above" or "over" the other elements or features. Thus, the term "below" can cover both the above and below positions and orientations. The device may be oriented in other ways (e.g., rotated 90 degrees or in other orientations), and the spatial relative descriptors used herein are to be interpreted accordingly. Similarly, descriptions of movement along various axes (translation) and rotation about various axes include a variety of spatial device positions and orientations. A combination of the position and orientation of a body defines the pose of the body.

[0064] Similarly, unless the context indicates otherwise, geometric terms such as "parallel", "perpendicular", "circular", or "square" are not intended to require absolute mathematical precision. Instead, such geometric terms allow for variations due to manufacturing or equivalent functionality. For example, if an element is described as "circular" or "substantially circular", a component that is not precisely circular (e.g., slightly oval or multi-faceted polygonal) is still covered by the description.

[0065] In addition, unless the context indicates otherwise, the singular forms "a", "an", and "the" are also intended to include the plural forms. The terms "comprises", "comprising", "has", etc. specify the presence of the stated features, steps, operations, elements, components, etc., but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, or groups.

[0066] Unless otherwise indicated, the terms device, medical device, instrument, and their variants may be used interchangeably.

[0067] Aspects of the invention are described with reference to a teleoperated surgical system. An example architecture of such a teleoperated surgical system is the da commercially available from Intuitive Surgical, Inc. in Sunnyvale, California Surgical systems. However, those skilled in the art will understand that the inventive aspects disclosed herein can be implemented and realized in various ways, including computer-assisted, non-computer-assisted, and hybrid combinations of manual and computer-assisted implementation and realization methods. The implementation methods are presented only as examples and should not be considered as limiting the scope of the inventive aspects disclosed herein. Where applicable, the inventive aspects can be implemented and realized in both relatively small, handheld, manually operated devices and relatively large systems with additional mechanical supports.

[0068] Figure 1 FIG. is a plan view illustration of a remotely operated surgical system (“system”) 1000 (“remote surgical system”) that operates under at least partial computer assistance. Both the remote surgical system 1000 and its components are considered medical devices. The remote surgical system 1000 is a minimally invasive robotic surgery (MIRS) system for performing minimally invasive diagnostic or surgical procedures on a patient P lying on an operating table 1010. The system can have any number of components, such as a user control unit 1100 used by an operator of the system (e.g., a surgeon or other skilled clinician S) during the procedure. The MIRS system 1000 can also include a manipulator unit 1200 (commonly referred to as a surgical robot) and an optional auxiliary equipment unit 1150. The manipulator unit 1200 can include an arm assembly 1300 and a surgical instrument tool assembly removably coupled to the arm assembly. The manipulator unit 1200 can manipulate at least one removably coupled medical device (instrument) 1400 (e.g., a force-sensing medical device) through a minimally invasive incision or natural orifice in the patient P while the surgeon S observes the surgical site and controls the movement of the instrument 1400 through the control unit 1100. Images of the surgical site are obtained by an endoscope such as a stereoscopic endoscope (not shown), which can be manipulated by the manipulator unit 1200 to orient the endoscope. The auxiliary equipment unit 1150 can be used to process the images of the surgical site for subsequent display to the surgeon S through the user control unit 1100. The number of instruments 1400 used once typically depends on the diagnostic or surgical procedure, as well as space limitations in the operating room and other factors. If it is necessary to replace one or more of the instruments 1400 being used during the surgery, an assistant removes the instrument 1400 from the operating unit 1200 and replaces it with another instrument 1400 from a tray 1020 in the operating room. Although shown as being used with the instrument 1400, any of the instruments described herein can be used with the system 1000.

[0069] Figure 2is a perspective view of the user control unit 1100. The user control unit 1100 includes a left-eye display 1112 and a right-eye display 1114 for presenting a depth-perceptive coordinated stereoscopic view of the surgical site to the surgeon S. The user control unit 1100 also includes one or more input control devices 1116 (input devices), which in turn cause the manipulator unit 1200 ( Figure 1 as shown) to manipulate one or more tools. The input devices 1116 provide at least the same degrees of freedom as the instruments 1400 associated with them to give the surgeon S a sense of telepresence or that the input devices 1116 are integral with (or directly connected to) the instruments 1400. In this way, the user control unit 1100 gives the surgeon S a strong sense of directly controlling the instrument 1400. To this end, position sensors, force sensors, strain sensors, or tactile feedback sensors (not shown), or any combination of such sensations, are returned from the instrument 1400 to one or more hands of the surgeon via one or more input devices 1116.

[0070] The user control device 1100 is shown in Figure 1 the same room as the patient such that the surgeon S can directly monitor the procedure, be physically present if necessary, and communicate directly with an assistant rather than by phone or other communication medium. However, in other embodiments, the user control unit 1100 and the surgeon S can be in different rooms, completely different buildings, or other locations remote from the patient, thus allowing for a remote surgical procedure.

[0071] Figure 3 is a perspective view of the auxiliary device unit 1150. The auxiliary device unit 1150 can be coupled to an endoscope (not shown) and can include one or more processors to process the captured images for subsequent display, for example, via the user control unit 1100 or on another suitable display located locally (e.g., on the unit 1150 itself as shown, on a wall-mounted display) and / or remotely. For example, in the case of using a stereoscopic endoscope, the auxiliary device unit 1150 can process the captured images to present a coordinated stereoscopic image of the surgical site to the surgeon S via the left-eye display 1112 and the right-eye display 1114. Such coordination can include alignment between the relative images and can include adjusting the stereoscopic working distance of the stereoscopic endoscope. As another example, image processing can include compensating for imaging errors of the image capture device, such as optical aberrations, using previously determined camera calibration parameters.

[0072] Figure 4A front perspective view of the manipulator unit 1200 is shown. The manipulator unit 1200 includes components for providing manipulation of the instrument 1400 (e.g., arms, linkages, motors, sensors, etc.) and an imaging device (not shown) for capturing images of the site of the procedure, such as a stereoscopic endoscope. Specifically, the instrument 1400 and the imaging device may be manipulated by a remote operating mechanism having one or more mechanical joints. In addition, the instrument 1400 and the imaging device are positioned and manipulated through an incision or natural orifice within the patient P such that the center of motion, which is remote from the manipulator and is typically located along the instrument axis, is maintained at the incision or orifice by kinematic mechanical or software constraints. In this way, the incision size can be minimized.

[0073] Figure 5 is a schematic diagram of a medical device 2400 (e.g., an instrument) according to an embodiment. In some embodiments, the medical device 2400 or any component thereof is optionally part of a surgical system that performs a surgical procedure. The surgical system may include a manipulator unit, a series of motion linkages, a series of cannulas, etc. The medical device 2400 (and any instrument described herein) may be used in any suitable surgical system (e.g., the MIRS system 1000 shown and described above). The medical device 2400 includes a proximal mechanical structure 2700, a shaft 2410 coupled to the proximal mechanical structure 2700, a force sensor system including a distal force sensor unit 2800, a tool 2462 coupled to the distal force sensor unit 2800, a drive element 2420 coupled between the tool 2462 and the proximal mechanical structure, and an electronic circuit board 2920 coupled within or to the proximal mechanical structure 2700. The distal force sensor unit 2800 includes a beam 2810 coupled to the shaft 2410. The tool 2462 may include, for example, engagable jaws or another suitable surgical tool coupled to a linkage (not shown). In some embodiments, the linkage may be included in a wrist assembly having a plurality of engaging linkages. The shaft 2410 includes a distal portion 2412 coupled to the proximal portion of the beam 2810 and a proximal portion 2411 coupled to the proximal mechanical structure 2700. The drive element 2420 may be, for example, a cable, a belt, a rod, etc. The proximal mechanical structure 2700 may include components configured to actuate the drive element 2420, which causes one or more components of the surgical instrument, such as, for example, the tool 2460, to move. The proximal mechanical structure 2700 may be similar to the proximal mechanical structure 4700 described in more detail below with reference to the medical device 4400. As Figure 5 shown, an electrical ground path GP is defined between the tool 2462 and / or the distal force sensor unit 2800 and the electronic circuit board 2920, as described in more detail below.

[0074] Typically, during a medical procedure, the tool 2462 contacts anatomical tissue, which can generate forces in the x and y directions or in the z direction (e.g., see Figure 8 the x, y, and z axis directions shown), the x and y direction forces can be radial, lateral, or perpendicular to the long axis of the shaft, and the z direction force is axial or parallel to the long axis of the shaft. In some embodiments, one or more strain sensors (not shown) that can include one or more strain gauges can be coupled to the beam 2810 of the distal force sensor unit 2800 to measure the strain in the beam during operation of the medical device. The measured beam strain can be used to determine the forces applied to the tool 2462 in the x and y axis directions. These x and y axis forces are transverse (e.g., perpendicular) to the z axis (which is parallel or collinear with the central axis C of the beam b ).

[0075] As described above, when the medical device is a cauterizing device that provides electrical energy, there is typically an insulator between the drive pulley of the tool 2462 in which the drive element 2420 engages and the tool (e.g., "jaws") itself that is exposed to the electrical energy. The presence of the insulator causes the components between the tool 2462, the distal force sensor unit 2800, and the drive element 2420 to typically be at a lower voltage. In the case where the medical device is a non-cauterizing instrument and there is no insulator between the tool 2462 and the drive pulley on the tool 2420, but the tool 2462 is still energized by electrical energy, the drive pulley, the distal force sensor unit 2800, and the ground plane of the electronic circuit board 2920 can all be at a high voltage. For example, the tool can be energized by contact with another power source or medical device. Thus, a ground path GP is provided between the tool 2462 and the electronic circuit board 2920 to accommodate this higher voltage and create a "floating ground" at the electronic circuit board 2920 relative to the voltage at the distal end of the medical device 2400. In other words, the floating ground holds the electronic circuit board 2920 at the same voltage as the voltage at the distal end of the medical device 2400. To establish the ground path GP, the drive element 2420 is electrically connected to the electronic circuit board 2920 by a ground screw ( Figure 5 not shown in) to hold the drive element 2420, the drive pulley, and the distal force sensor unit 2800 all at the same ground voltage. In some embodiments, the ground plane of the electronic circuit board 2920 can include a conductive layer that serves as a conductive shield for electrical grounding. In alternative embodiments, the conductive shield can be a separate conductive component that is positioned to serve as a conductive shield for electrical grounding.

[0076] As described above and as Figure 5As shown, a ground path GP is defined from the tool 2462 to the electronic circuit board 2920. In some embodiments, the ground path GP is defined as a conductive layer from the distal force sensor unit 2800 to the electronic circuit board 2920. This maintains a ground, for example, from the beams of the distal force sensor unit 2800 to the conductive layer. As previously described, the force sensing signals from the distal force sensor unit 2800 need to be protected from or substantially unaffected by the energy caused by cauterization or other electrical energy applied to the tool 2462. Thus, when the distal force sensor unit 2800 and the drive element 2420 are powered on, the electronic circuit board 2920 is electrically connected to the drive element 2420 such that the distal force sensor unit 2800 and the drive element 2420 are at the same ground voltage. Accordingly, the ground path GP provides a low impedance ground connection between the tool 2462 and / or the distal force sensor unit 2800 and the circuit board 2920. This arrangement minimizes or eliminates any voltage difference between these components at the distal end of the medical device 2400 and the circuit board 2920 that may be generated by voltage losses due to higher impedance. In some embodiments, the impedance of the ground path GP is less than about 1 ohm. In other embodiments, the impedance of the ground path GP is less than about 2 ohms.

[0077] As described herein, in some embodiments, the conductive layer of the electronic circuit board 2920 extends under or distally of the inductive coil force sensor. The inductive coil force sensor is positioned relative to the conductive layer such that a close separation and spatial uniformity of capacitive coupling between the sensor and the conductive layer in the electronic circuit board 2920 are maintained. This positioning limits the possibility that eddy currents from the sensor create spatial non-uniformities in the potential of the electronic circuit board 2920. Accordingly, a uniform separation distance in multiple directions is established between the inductive force sensor and the conductive layer of the electronic circuit board 2920. In some embodiments, a gap ( Figure 5 (not shown in figure) is defined in the conductive layer of the electronic circuit board 2920, which limits the possibility that eddy currents in the inductive coil sensor create spatial non-uniformities in the potential of the electronic circuit board 2920. In such embodiments, the conductive layer (i.e., the ground plane) spans the entire surface area of the electronic circuit board 2920 and is partitioned around the area where the inductive coil sensor is positioned to protect the ground path GP defined between the distal force sensor beams and the electronic circuit board 2920 from the magnetic field caused by the inductive coil sensor.

[0078] Figure 6Schematic diagram of a part of a medical device 3400 according to another embodiment. In some embodiments, the medical device 3400 or any component thereof is optionally part of a surgical system that performs a surgical procedure, and it may include a manipulator unit, a series of motion linkages, a series of cannulas, etc. The medical device 3400 (and any instrument described herein) can be used in any suitable surgical system (such as the MIRS system 1000 shown and described above). The medical device 3400 includes a proximal mechanical structure 3700, an electronic circuit board 3920 coupled to or disposed within the proximal mechanical structure 3700, a plurality of conductive traces 3925, an electrically grounded conductive shield 3922 positioned distally below the conductive traces 3925, and a force sensor system including a proximal force sensor unit 3900. The proximal force sensor unit 3900 includes a sensor element 3912 positioned proximally above the conductive traces 3925. As Figure 6 shown, there is a physical electrical connection between one or more of the conductive traces 3925 and the sensor element 3912, and there is no physical electrical connection between the sensor element 3912 and the conductive shield 3922.

[0079] In some embodiments, the conductive traces 3925 can optionally be electrically coupled to ground (as Figure 6 shown), which can be, for example, a local ground or a ground to earth. In some embodiments, the medical device 3400 further includes a distal force sensor unit (not shown in Figure 6 as described above for the medical device 2400) and a sensor signal cable (not shown) electrically coupled between the distal force sensor unit and the electronic circuit board 3920. The sensor signal cable can include an electrically grounded trace, and the electrically grounded trace of the sensor signal cable can define a part of a second ground path between the distal force sensor unit and electrical ground. In this way, the force sensor system includes a primary ground path (GP as described above) and a secondary ground path. This arrangement creates a low impedance ground connection between the tool 2462 and / or the distal force sensor unit 2800 and the circuit board 2920.

[0080] Although Figure 6Although not shown in the figure, the medical device 3400 may further include a shaft coupled to the proximal mechanical structure 3700, a distal force sensor unit including a beam coupled to the shaft, an end effector including a tool coupled to the distal portion of the beam, and a drive element coupled between the tool and the proximal mechanical structure 3700, as described above for the medical device 2400. The tool may include, for example, engagable jaws or another suitable surgical tool coupled to a linkage (not shown). In some embodiments, the linkage may be included in a wrist assembly having a plurality of engaging linkages. The shaft may include a distal portion coupled to the proximal portion of the beam and a proximal portion coupled to the proximal mechanical structure 3700. The drive element may be, for example, a cable, a belt, a rod, etc. The proximal mechanical structure 3700 may include components configured to actuate the drive element, which causes movement of one or more components of the surgical instrument, such as, for example, the tool. The proximal mechanical structure 3700 may be similar to the proximal mechanical structure 4700 described in more detail below with reference to the medical device 4400. An electrical ground path may also be defined between the tool and the electronic circuit board 3920. In some embodiments, the drive element defines a portion of the electrical ground path between the distal force sensor unit and electrical ground, or between the tool and electrical ground, or between both the distal force sensor unit and the tool and electrical ground.

[0081] The proximal force sensor unit 3900 (and any proximal force sensor unit described herein) may be used to measure the axial force applied to the end effector (i.e., in the z-axis direction parallel to the central axis of the beam of the distal force sensor unit) (see, for example, Figure 8 the x, y, and z-axis directions in). For example, an axial force applied to the end effector in the z-axis direction may cause an axial displacement of the shaft in a direction along the central axis of the shaft (substantially parallel to the beam central axis C b ). The axial force in the z-direction may be in the proximal direction (e.g., a reaction force generated by pushing against tissue with the end effector), or it may be in the distal direction (e.g., a reaction force generated by pulling on tissue grasped by the end effector). In some embodiments, the shaft may be coupled to the proximal mechanical structure 3700 via a biasing mechanism (e.g., a linkage or a spring-loaded coupler, not shown) such that the amount of travel of the shaft relative to the proximal mechanical structure 3700 may be related to the magnitude of the axial force in the z-direction applied to the end effector. In this way, measuring the distance the shaft moves relative to the proximal mechanical structure 3700 can be used to determine the axial force in the z-direction. Additional details regarding such embodiments are described in International PCT Application No. PCT / US2021 / 049792, which is incorporated herein by reference above.

[0082] In some embodiments, the sensor element 3912 of the proximal force sensor unit 3900 is an inductive coil sensor that includes a coil assembly, linkage, and microprocessor similar to or the same as those described in International PCT Application No. PCT / US2021 / 049792 (none of which are shown in Figure 6 ), which International PCT Application is incorporated herein by reference above. The proximal force sensor unit 3900 may optionally include two sensor elements 3912, each of which may be an inductive coil sensor. In such an embodiment, there is a physical electrical connection between one or more of the plurality of conductive traces 3925 and the second sensor element, and there is no physical electrical connection between the second sensor element and the conductive shield 3922.

[0083] As described above, the conductive shield 3922 extends beneath or distal to the sensor element 3912, and in embodiments having two sensor elements, the conductive shield 3922 also extends beneath or distal to the second sensor element. The sensor element 3912 and the second sensor element are positioned relative to the conductive shield 3922 such that the spatial uniformity of the capacitive coupling between the sensor element and the conductive shield 3922 is maintained. As described above, this limits the possibility of eddy currents from the sensor element creating spatial non-uniformities in the potential of the electronic circuit board 3920. Accordingly, a uniform separation distance is established in multiple directions between the sensor element and the conductive shield 3922 of the electronic circuit board 3920. More details regarding such embodiments are described below with reference to the medical device 4400.

[0084] In some embodiments, a gap is defined in the conductive shield 3922 to further limit the possibility of eddy currents in the sensor element creating spatial non-uniformities in the potential of the electronic circuit board 3920. In such an embodiment, the conductive shield 3922 spans the entire circuit board surface area and is partitioned around the sensor element to protect the ground path defined between the proximal force sensor unit and the electronic circuit board 3920 (as described above for Figure 5 ) from inductive coupling between the sensor element and the conductive shield 3922.

[0085] In some embodiments, the electronic circuit board includes a first layer and a second layer positioned distally beneath the first layer. In some such embodiments, the first layer includes the conductive traces 3925, the second layer includes the conductive shield 3922, and a portion of the first layer extends proximally over the gap.

[0086] In some embodiments, the electronic circuit board 3920 includes an opening and an outer edge ( Figure 6(not shown in the figure), and the conductive shield 3922 surrounds the opening. In some such embodiments, a gap in the conductive shield is defined between the opening in the electronic circuit board 3920 and the outer edge of the electronic circuit board 3920.

[0087] Figures 7 to 17 Another medical device is shown that includes a proximal force sensor unit configured and positioned to mitigate electromagnetic interference. In some embodiments, the medical device 4400 or any component thereof is optionally part of a surgical system that performs a surgical procedure, and it may include a manipulator unit 4200, a series of motion linkages, a series of cannulas, etc., and a control unit 4100. The manipulator 4200 and the control unit 4100 may be configured to be the same as or similar to the manipulator 1200 and the control unit 1100 described above for the surgical system 1000, and function the same as or similar to the manipulator 1200 and the control unit 1100 described above for the surgical system 1000. The medical device 4400 (and any instrument described herein) may be used in any suitable surgical system (such as the MIRS system 1000 shown and described above). The medical device 4400 includes a proximal mechanical structure 4700, a force sensor system including a proximal force sensor unit 4900 and a distal force sensor unit 4800, a shaft 4410 coupled to the proximal mechanical structure 4700 and the proximal force sensor unit 4900, and an end effector 4460 coupled to the wrist assembly 4500 at the distal portion of the medical device 4400. The proximal mechanical structure 4700 may be coupled to the manipulator unit 4200, which may be directly or indirectly coupled to the control unit 4100. As for example Figure 8 shown, the medical device 4400 also includes one or more drive elements 4420 that couple the proximal mechanical structure 4700 to the wrist assembly 4500 and the end effector 4460. The drive elements 4420 may be, for example, cables, belts, etc. The medical device 4400 is configured such that a selected movement of the drive elements 4420 produces a rotation of the wrist assembly 4500 about a first axis of rotation A1 (see Figure 8 )(which serves as a pitch axis; the term pitch is arbitrary) (i.e., a pitch rotation), and a rotation of the end effector 4460 about a second axis of rotation A2 (see Figure 8)(which serves as the yaw axis; the term yaw is arbitrary) a yaw rotation, a cutting or gripping rotation of the tool member of the end effector 4460 about the second rotation axis A2, or any combination of these motions. Changing the pitch or yaw of the instrument 4400 can be performed by manipulating the drive element 4420 in a manner similar to that described, for example, in U.S. Patent No. US 8,821,480 B2 (filed July 16, 2008) entitled "Four-Cable Wrist with Solid Surface Cable Channels", which is incorporated herein by reference in its entirety. Accordingly, the specific motions by which each of the drive elements accomplishes the desired motion are not described below.

[0088] The shaft 4410 includes a proximal portion 4411 coupled to the proximal mechanical structure 4700 and a distal portion 4412 of the beam 4810 coupled to the distal force sensor unit 4800. The beam 4810 may include or be coupled with one or more strain sensors 4830 to measure the forces applied to the surgical instrument in the x and y directions during a surgical procedure. Although the beam 4810 with strain sensors 4830 is shown and described in this embodiment, in other embodiments, the beam 4810 and strain sensors 4830 may not be included. As Figure 8 shown, the sensor signal cable 4840 is electrically coupled between the distal force sensor unit 4800 and the electronic circuit board 4920. The sensor signal cable 4840 includes one or more electrical ground traces 4890. The sensor signal cable 4840 extends proximally through the shaft 4410 and is coupled to the bottom or distal side of the electronic circuit board 4920 as Figure 17 shown, and carries the strain signal to the electronic circuit board 4920, as described above for the medical device 3400. Additional details regarding the sensor signal cable are provided in U.S. Provisional Patent Application No. 63 / 425,520, filed November 15, 2022, the disclosure of which is incorporated herein by reference.

[0089] The proximal portion 4411 of the shaft 4410 is coupled to the proximal mechanical structure 4700 in a manner that allows the shaft 4410 to translate in the z-axis direction relative to the proximal mechanical structure 4700. Allowing the shaft 4410 to translate in the z direction relative to the proximal mechanical structure 4700 facilitates the measurement of forces along the z-axis, as described herein and in more detail in International PCT Application No. PCT / US2021 / 049792, which is incorporated by reference above. The shaft 4410 also defines a lumen (not shown) and / or a plurality of channels through which drive elements and other components (e.g., wires, ground wires, etc.) can be routed from the proximal mechanical structure 4700 to the wrist assembly 4500.

[0090] The end effector 4460 includes a first tool 4462 and a second tool 4482 each having a contact portion configured to engage or manipulate target tissue during a surgical procedure. For example, in some embodiments, the contact portion may include an engagement surface that serves as a clamp, cutter, tissue manipulator, etc. In other embodiments, the contact portion may be an energized tool member for cauterization or electrosurgical procedures. The end effector 4460 is operatively coupled to a proximal mechanical structure 4700 such that the tools 4462 and 4464 rotate relative to the shaft 4410 about a first axis of rotation A1.

[0091] As previously described, during a medical procedure, the tools 4462, 4482 of the end effector 4460 contact anatomical tissue, which can generate forces in the x, y, or z directions applied to the tools 4462, 4482 (e.g., see the x, y, and z axis directions shown in Figure 8 ). The strain sensor 4830 can measure the strain in the beam 4810 during operation of the medical device 4400. The measured beam strain can be used to determine the forces applied to the tools 4462, 4482 in the x-axis and y-axis directions. These x-axis and y-axis forces are transverse (e.g., perpendicular) to the z-axis (which is parallel or collinear with the central axis of the beam).

[0092] The proximal mechanical structure 4700 includes a chassis that supports or contains components configured to actuate a drive element 4420, the actuation of which causes movement of one or more components of the surgical instrument, such as, for example, the wrist assembly 4500 or the tools 4462, 4482. The drive element 4420 extends from the proximal mechanical structure 4700 to drive pulleys 4467 and 4487 of the end effector 4460 for the tools 4462 and 4482, respectively (see Figure 9 ). As shown in Figure 9 and Figure 10 , the proximal mechanical structure 4700 further includes: an instrument support structure that includes a base 4770; an electronic circuit board 4920; a proximal force sensor unit 4900; and a common mode choke 4763. The common mode choke 4763 can be used to reduce interference with the electronic circuit board 4920. For example, because the ground path GP can be a floating ground (i.e., not a ground to earth), in some cases, the ground path GP may be at a higher voltage due to energization of the instrument as described herein. In such cases, the common mode choke 4763 can block the flow of current that would otherwise flow to the chassis of the proximal mechanical structure 4700. In other embodiments, various support structures may optionally be used, such as a chassis, frame, bed, a combined peripheral outer body of the proximal mechanical structure, etc.

[0093] The proximal mechanical structure 4700 surrounds (or is coupled to) a proximal force sensor unit 4900, which includes a coil assembly 4915, a linkage assembly 4950 acting as a movable four-bar linkage, and a microprocessor (see the example microprocessor in FIG. 20). The coil assembly 4915 includes a first inductive coil sensor element 4912 (also referred to as the first sensor element), a second inductive coil sensor element 4914 (also referred to as the second sensor element), a first rod (not shown), a second rod (not shown), a first magnet (not shown) coupled to the first rod, a second magnet (not shown) coupled to the second rod, and a mounting bracket 4937. The mounting bracket 4937 is fixed within the proximal mechanical structure 4700 and is electrically coupled to the electronic circuit board 4920 via wiring 4935 (shown in Figures 12A to 1 3C). The first sensor element 4912 and the second sensor element 4914 are each mounted within the mounting bracket 4937 and are positioned side by side with each other, and are electrically coupled to the electronic circuit board 4920. The first sensor element 4912 and the second sensor element 4914 are each inductive coils, and are each wound around a cylinder of a non-conductive material such as, for example, PEEK. The first sensor element 4912 and the second sensor 4914 can be made to have the same characteristics, such as coil length, coil width, and thickness of the coil wiring. The rods are coupled to the linkage assembly 4950, which is coupled to the shaft 4410 such that translational movement of the shaft 4410 in the z-axis direction causes the rods and the magnets coupled thereto to translate in the z-axis direction within the first sensor element 4912 and the second sensor element 4914. This movement causes a change in the inductance at the coils, and the change in the inductance can be used to measure the change in the position of the shaft 4410, which can be converted into a z-axis force measurement. Additional details regarding the components and functions of the proximal mechanical structure are described in International PCT Application No. PCT / US2021 / 049792, which is incorporated herein by reference above.

[0094] As Figure 11As shown, the proximal mechanical structure 4700 also includes one or more idler pulleys 4930, one or more pulley shafts 4932, and a pulley cover 4934. The drive element 4420 is routed around the idler pulley 4930 and is thus electrically coupled to the pulley shaft 4932. The pulley cover 4934 is positioned proximally above the idler pulley shaft 4932 and is electrically coupled to the idler pulley shaft 4932 (e.g., via a bushing or bearing). The pulley cover 4934 is also electrically coupled to the electronic circuit board 4920 via a ground screw 4936 and a washer 4938. An O-ring 4940 is positioned between the electronic circuit board 4920 and the pulley cover 4934 to prevent corrosion at the electronic circuit board 4920. A plating component (not shown) is also provided inside the pulley cover 4930, near or at the location of attachment to the electronic circuit board 4920. The plating component can improve the electrical coupling (i.e., reduce the resistance) between the pulley cover 4930 and the electronic circuit board 4920 (and the ground plane therein). With this arrangement, the drive element 4420 provides a low-resistance ground path GP from the distal end of the medical device to the electronic circuit board 4920.

[0095] As previously described herein, when the medical device is a cauterizing device that provides electrical energy, there is an insulator (not shown) between the drive pulleys 4467, 4487 of the tools 4462, 4482 in which the drive element 4420 engages and the tools 4462, 4482 (e.g., “jaws”) that are exposed to the electrical energy. The presence of the insulator keeps the components between the tools 4462, 4482, the distal force sensor unit 4800, and the drive element 4420 at a generally lower voltage. In the case where the medical device is a non-cauterizing instrument and there is no insulator between the tools 4462, 4482 and the drive pulleys 4467, 4487, but the tools 4462, 4482 are still energized by electrical energy, the ground planes of the drive pulleys 4467, 4487, the distal force sensor unit 4800, and the electronic circuit board 4920 can all be at a high voltage. For example, the tools 4462, 4482 can be energized by contact with another power source or medical device. Therefore, a ground path GP is provided between the tools 4462, 4482 and the electronic circuit board 4920 to accommodate this higher voltage (see Figure 12A and Figure 12B) and maintain the components at the same ground voltage. More specifically, the drive element 4420 is electrically connected to the electronic circuit board 4920 via a ground screw 4936 to maintain the drive element 4420, the pulleys 4467, 4487, and the distal force sensor unit 4800 all at the same ground voltage. As described above, a floating ground is generated at the electronic circuit board 4920, and this floating ground maintains the electronic circuit board 4920 at the same voltage as the voltage at the distal end of the medical device 4400. In some applications (e.g., in the case of an energizing device), the potential of the floating ground can be higher than zero.

[0096] As Figure 12A and Figure 12B shown, the ground path GP is defined to extend from the tools 4462, 4482 to the drive element 4420, to the idler pulley 4930, the pulley shaft 4932, the pulley cover 4934, to the ground screw 4936, to the electronic circuit board 4920, to the common mode choke 4763 in the proximal mechanical structure 4700, and to the control unit 4100. More specifically, in this embodiment, the electronic circuit board 4920 includes: a first layer 4921 that includes one or more conductive traces 4925 (see Figure 15 ); and a second layer 4922 (see Figure 16 ) that includes a conductive material that serves as an electrically conductive shield for electrical grounding. The first layer 4921 is positioned above or proximal to the second layer 4922. The ground path GP is defined to extend from the tools 4462, 4482 to the drive element 4420, to the idler pulley 4930, the pulley shaft 4932, the pulley cover 4934, to the ground screw 4936, to the electrically grounded conductive second layer 4921 of the electronic circuit board 4920, to the common mode choke 4763 in the proximal mechanical structure 4700, and to the control unit 4100. As described above, the common mode choke 4763 can be used to reduce interference to the electronic circuit board 4920. For example, because the ground plane of the electronic circuit board 4920 is a floating ground with respect to the voltage at the distal end of the medical device 4400, the electronic circuit board 4920 may be at a high ablation potential in some cases, and in such cases, current will tend to flow to the support structure of the proximal mechanical structure 4700. In this case, if the current flows in the same direction along different wirings of the medical device 4400 (such as, for example, ground wires, power lines, and drive cables), the common mode choke 4763 blocks the current.

[0097] In some embodiments, the ground path GP is defined as the conductive second layer 4922 extending from the distal force sensor unit 4800 to the electronic circuit board 4920. This maintains a ground connection, for example, from the beam 4810 of the distal force sensor unit 4800 to the conductive second layer 4922. As previously described, with this ground configuration, the force sensing signal from the distal force sensor unit 4800 can be isolated from the energy caused by cauterization or other electrical energy applied to the tools 4462, 4482. Thus, when the distal force sensor unit 4800 and the drive element 4420 are powered on, the electronic circuit board 4920 is electrically connected to the drive element 4420 such that the distal force sensor unit 4800 and the drive element 4420 are at the same ground voltage.

[0098] As described herein, the electronic circuit board 4920 extends beneath or distally of the sensor elements 4912, 4914. The sensor elements are positioned relative to the conductive second layer 4921 of the electronic circuit board 4920 such that the spatial uniformity of the capacitive coupling between the sensor elements 4912, 4914 and the conductive second layer 4922 is maintained. This limits the possibility of eddy currents from the sensor elements 4912, 4914 creating spatial non-uniformities in the potential of the electronic circuit board 4920. Thus, a uniform separation distance in multiple directions is established between the inductive force sensor elements 4912, 4914 and the conductive second layer 4921 of the electronic circuit board 4920.

[0099] More specifically, as for example Figures 13A to 14C shown, the electronic circuit board 4920 defines an opening 4923 and an outer peripheral edge 4924. The electronic circuit board 4920 and the conductive second layer 4922 of the electronic circuit board 4920 extend at least partially beneath or distally of the sensor elements 4912, 4914 such that the rods and magnets (not shown) of the sensor elements 4912, 4924 can extend through the opening 4923 and be connected to the linkage 4950 and the shaft 4410 as described above. There is a physical electrical connection between one or more of the plurality of conductive traces 4925 (see Figure 15 ) in the first layer 4921 and the sensor elements 4912, 4914 via the wiring connection 4935 and the spring pins 4941 (see Figure 14C ). However, there is no physical electrical connection between the sensor elements 4912, 4914 and the conductive second layer 4922. As for example Figures 14A to 14CAs shown, the sensor elements 4912, 4914 are positioned relative to the second conductive layer 4922 such that the spatial uniformity of the capacitive coupling between the sensor elements 4912, 4914 and the second conductive layer shield 4922 is maintained. By extending the outer periphery 4924 past the sensor element 4912, the capacitive coupling between the second conductive layer 4922 and the sensor element 4912 is substantially the same as the capacitive coupling between the second conductive layer 4922 and the sensor element 4914. As described above, this limits the possibility of eddy currents from the sensor elements 4912, 4914 creating spatial non-uniformities in the potential of the electronic circuit board 4920. For example, as Figure 14B shown in the top view of, the sensor element 4912 and the sensor element 4914 are each positioned equidistantly above the electronic circuit board 4920 and the opening 4923 in both the X and Y directions. As Figure 14C shown, the first sensor element 4912 is spaced a distance d1 from the electronic circuit board 4920 in the z direction, and the second sensor element 4914 is spaced a distance d2 from the electronic circuit board 4920 in the z direction, where d1 is equal to d2. Thus, a uniform separation distance in multiple directions (x, y, and z directions) is established between the sensor elements 4912, 4914 and the second conductive layer 4922 of the electronic circuit board 4920.

[0100] In addition, as Figure 16 shown, the second conductive layer 4922 includes a gap 4926 defined between the opening 4923 and the outer periphery 4924 of the electronic circuit board 4920. The gap 4926 is provided to further limit the possibility of eddy currents in the inductive coil sensor elements 4912, 4914 creating spatial non-uniformities in the potential of the electronic circuit board 4920. In such an embodiment, the conductive material of the second layer 4922 spans the entire surface area of the second layer 4922 of the electronic circuit board 4920 and is divided around the inductive coil sensor elements 4912, 4914 to protect the ground path GP from the magnetic fields induced by the inductive coil sensor elements 4912, 4914.

[0101] Figure 18A block diagram of a portion of an embodiment of a proximal force sensor unit 5900 that can be implemented to measure an axial force applied to the instrument shaft 5410. The proximal force sensor unit 5900 can be implemented as an inductive z-axis force sensor unit as described above for any previous embodiment, including the proximal force sensor unit 5900. As described above, an axial force on the instrument shaft 5410 causes an axial movement of the instrument shaft 5410, which can be detected by the proximal force sensor unit 5900. The proximal force sensor unit 5900 can include a coil assembly 5915 as described herein, the coil assembly 5915 including paired coils 5912 and 5914, wherein rods 5916 and 5918 are respectively movably positioned within coils 5912 and 5914. Rod 5916 can have a magnet 5931 coupled thereto, and rod 5918 can have a magnet 5933 coupled thereto.

[0102] Coil 5912 can be coupled through capacitor C to a multi-channel frequency detection block 5965, and the capacitor C can form an inductor / capacitor (LC) circuit with coil 5912, the LC circuit having an inductance contribution based on the distance that rod 5916 and magnet 5931 move within coil 5912. Coil 5914 can be coupled through capacitor C to the multi-channel frequency detection block 5965, and the capacitor C can form an LC circuit with coil 5914, the LC circuit having an inductance contribution based on the distance that rod 5918 and magnet 5933 move within coil 5914. The LC circuits associated with coils 5912 and 5914 can be implemented with different capacitances in an implementation that takes such differences into account.

[0103] The multi-channel frequency detection block 5965 can be implemented as a precision dual-inductance sensor for measuring inductance. In the case where capacitor C forms an LC circuit with coil 5912 at the input of the multi-channel frequency detection block 5965, the multi-channel frequency detection block 5965 can output a first signal associated with the frequency of the circuit, such as the ratio of the frequency to a known reference frequency. In the case where capacitor C forms an LC circuit with coil 5914 at the input of the multi-channel frequency detection 5965, the multi-channel frequency detection block 5965 can output a second signal associated with the frequency of the circuit, such as the ratio of the frequency to a known reference frequency. The multi-channel frequency detection block 5965 can output N digital signals to the microprocessor 5952. For two LC circuits, the multi-channel frequency detection block 5965 can output two digital signals to the microprocessor 5970.

[0104] The microprocessor 5952 may include or have access to an EEPROM 5972 or other storage device, which may include calibration values for implementing magnets 5931 within coil 5912 and magnets 5933 within coil 5914. In the measurement of the axial force on the instrument axis, this calibration value can be accessed to determine the distance each of the magnets 5931 and 5933 moves based on the frequencies received from the multi-channel frequency detection block 5965. The frequency difference can be stored in the EEPROM 5972 as an inductance difference (which is a function of distance). This distance difference can be associated with a reference position and the inductance difference. For the distance selected from the measured inductance difference, this distance can be used together with the spring constant stored in the EEPROM 5972, where the spring constant is a characteristic of a spring (e.g., the spring 5829 described above) through which the instrument axis 5410 is coupled to a support structure on which the proximal force sensor unit 5900 can be deployed.

[0105] The proximal force sensor unit 5900 may include other optional components. For example, the microprocessor 5952 may include a Universal Asynchronous Receiver / Transmitter (UART) interface 5974 or other communication interface to transmit (TX) digital outputs and receive (RX) digital signals. The received signals can be used to update the calibration values in the EEPROM 5972 of the microprocessor 5952. A common-mode choke 5763 (e.g., the common-mode choke 5863) can be used to reduce interference to other electronic circuit boards on the support structure on which the proximal force sensor unit 5900 is deployed. Optionally, the proximal force sensor unit 5900 may include a magnetic structure 5962 between the common-mode choke 5763 and the microprocessor 5952. The magnetic structure 5962 can be inserted to assist in reducing electromagnetic interference (EMI) radiation. The magnetic structure 5962 can be implemented as a ferrite bead. As described above, other magnetic material formats can be implemented for the magnetic structure 5962.

[0106] A machine-readable storage device can include any non-transitory mechanism for storing information in a form readable by a machine, such as a computer or a microprocessor assigned to perform a specific function. For example, a machine-readable storage device can include read-only memory (ROM), random access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, and other storage devices and media. In various embodiments of the medical device having a proximal force sensor unit described herein, the non-transitory machine-readable medium can include instructions that, when executed by one or more processors, can cause the system to perform operations, including but not limited to: (i) receiving a first signal generated by a first coil and associated with the position of a first magnet relative to the first coil; (ii) receiving a second signal generated by a second coil and associated with the position of a second magnet relative to the second coil, and wherein the first signal from the first coil and the second signal from the second coil are associated with a linear displacement along the central axis of an axis. The force sensor unit can include a microprocessor coupled to receive the first signal and the second signal. In various embodiments, the non-transitory machine-readable medium can include instructions that, when executed by one or more processors, cause the system to perform operations including performing methods of functions associated with the various embodiments described herein.

[0107] Although various embodiments have been described above, it should be understood that these embodiments are presented by way of example and not limitation. In cases where the above methods and / or diagrams indicate a particular order of occurrence of particular events and / or process patterns, the order of the particular events and / or operations can be modified. Although embodiments have been specifically shown and described, it should be understood that various changes can be made in form and detail.

[0108] For example, any instrument (and components thereof) described herein can optionally be part of a remote surgery system for performing minimally invasive surgical procedures, and the remote surgery system can include a manipulator unit, a series of kinematic linkages, a series of cannulas, etc. Thus, any instrument described herein can be used in any suitable surgical system (such as the MIRS system 1000 shown and described above). Additionally, any instrument shown and described herein can be used to manipulate target tissue during a surgical procedure. Such target tissue can be cancer cells, tumor cells, lesions, vascular occlusions, thrombi, stones, uterine fibroids, bone metastases, adenomyosis, or any other body tissue. The examples of target tissue presented are not an exhaustive list. Additionally, the target structure can also include artificial substances (or non-tissues) in or associated with the body, such as, for example, a stent, a portion of an artificial tube, a fastener in the body, etc.

[0109] For example, any component of the surgical instrument described herein can be constructed of any material (e.g., medical grade stainless steel, nickel alloy, titanium alloy, etc.). Additionally, any one of the linkages, tool members, beams, shafts, connectors, cables, or other components described herein can be constructed of multiple pieces that are later joined together. For example, in some embodiments, a linkage can be constructed by joining separately constructed components together. However, in other embodiments, any one of the linkages, tool members, beams, shafts, connectors, cables, or components described herein can be constructed as a single unit.

[0110] Although the instrument is generally shown as having a rotational axis of the tool member (e.g., axis A2) that is orthogonal to the rotational axis of the wrist member (e.g., axis A1), in other embodiments, any instrument described herein can include a rotational axis of the tool member that is offset at any suitable angle relative to the rotational axis of the wrist assembly. Although various embodiments have been described as having a combination of specific features and / or components, other embodiments having a combination of any features and / or components from any of the embodiments discussed above are also possible. Aspects have been described in the general context of medical devices, and more specifically surgical instruments, but the inventive aspects are not necessarily limited to use in medical devices.

Claims

1. A medical device, comprising: A shaft including a proximal portion and a distal portion; A tool movably coupled to the distal portion of the shaft; A distal force sensor unit coupled to the distal portion of the shaft; A proximal mechanical structure coupled to the proximal portion of the shaft; An electronic circuit board coupled to the proximal mechanical structure; And A drive element coupled between the tool and the proximal mechanical structure; Wherein actuation of the drive element causes movement of the tool; Wherein an electrical ground path is defined between the distal force sensor unit and the electronic circuit board; and Wherein the electrical ground path includes the drive element.

2. The medical device according to claim 1, wherein: The proximal mechanical structure includes a proximal pulley and a pulley cover at least partially covering the proximal pulley; The drive element is in electrical contact with the pulley; The proximal pulley is in electrical contact with the pulley cover; The pulley cover is in electrical contact with the electronic circuit board; and The ground path includes the proximal pulley and the pulley cover.

3. The medical device according to claim 1, wherein: The medical device further includes at least one of an O-ring, a washer, and a component coupled between the electronic circuit board and the proximal mechanical structure.

4. The medical device according to claim 1, wherein: The tool includes a tool pulley; and The drive element is electrically coupled to the tool pulley.

5. The medical device according to claim 1, wherein: The ground path is a first ground path; The medical device further includes a sensor signal cable electrically coupled between the distal force sensor unit and the electronic circuit board; A second electrical ground path is defined between the distal force sensor unit and the electronic circuit board; and The second ground path includes the sensor signal cable.

6. The medical device according to claim 1, wherein: The medical device further includes a proximal force sensor unit coupled to the electronic circuit board.

7. The medical device according to claim 6, wherein: The proximal force sensor unit is configured to measure a force applied to the tool in a direction along the length of the shaft.

8. The medical device according to claim 1, wherein: The electronic circuit board includes a first layer and a second layer; The first layer includes a plurality of conductive traces; The second layer includes a conductive material; and The conductive material of the second layer is electrically coupled to the electrical ground path.

9. The medical device according to claim 1, wherein: The tool is electrically insulated from the force sensor unit.

10. The medical device according to claim 1, wherein: The tool is in electrical contact with the ground path.

11. The medical device according to claim 1, wherein: The distal force sensor unit is configured to sense a force on the tool.

12. The medical device according to any one of claims 1 to 11, wherein: The medical device is configured as an instrument in a remote surgical system.

13. The medical device according to any one of claims 1 to 11, further comprising: A common mode choke coupled to the proximal mechanical structure, the common mode choke being configured to attenuate current flowing to the chassis of the proximal mechanical structure.

14. A medical device, comprising: Proximal mechanical structure; An electronic circuit board coupled to the proximal mechanical structure and including a plurality of conductive traces; An electrically grounded conductive shield positioned distally below the plurality of conductive traces; And A force sensor unit positioned proximally above the conductive traces and including a sensor element; Wherein there is a physical electrical connection between the sensor element and one or more of the plurality of conductive traces; and Wherein there is no physical electrical connection between the sensor element and the conductive shield.

15. The medical device according to claim 14, wherein: The medical device further includes a second sensor element; There is a physical electrical connection between the second sensor element and one or more of the plurality of conductive traces; There is no physical electrical connection between the second sensor element and the conductive shield; and The sensor element and the second sensor element are each spaced an equal distance from the conductive shield.

16. The medical device according to claim 14, wherein: The sensor element is an inductive coil sensor element.

17. The medical device according to claim 14, wherein: The conductive shield includes a gap positioned to prevent inductive coupling between the conductive shield and the sensor element.

18. The medical device according to claim 17, wherein: A portion of the first layer extends proximally over the gap.

19. The medical device according to claim 14, wherein: The medical device further includes a shaft coupled to the proximal mechanical structure; and The shaft is operably coupled to the force sensor unit such that translational movement of the shaft causes translational movement of a portion of the force sensor unit relative to the electronic circuit board.

20. The medical device according to claim 14, wherein: The electronic circuit board includes an opening and an outer edge; The conductive shield surrounds the opening of the electronic circuit board; and A gap in the conductive shield is defined between the opening of the electronic circuit board and the outer edge of the electronic circuit board.

21. The medical device according to claim 14, wherein: The medical device further includes an electrical ground; and One or more of the plurality of conductive traces are electrically connected to the electrical ground.

22. The medical device according to claim 14, wherein: The medical device further includes a shaft, a tool, and a distal force sensor unit; The shaft includes a proximal portion and a distal portion; The proximal portion of the shaft is coupled to the proximal mechanical structure; The tool is coupled to the distal portion of the shaft; And The distal force sensor unit is coupled to the distal portion of the shaft.

23. The medical device according to claim 22, wherein: The tool is electrically insulated from the distal force sensor unit.

24. The medical device according to claim 21, wherein: The medical device further includes a drive element operably coupled between the tool and the proximal mechanical structure such that actuation of the drive cable causes movement of the tool; and The drive element defines a portion of an electrical ground path between the distal force sensor unit and the electrical ground, between the tool and the electrical ground, or between both the distal force sensor unit and the tool and the electrical ground.

25. The medical device according to claim 21, wherein: The medical device further includes a sensor signal cable electrically coupled between the distal force sensor unit and the electronic circuit board; The sensor signal cable includes an electrical ground trace; and The electrical ground trace of the sensor signal cable defines a portion of the ground path between the distal force sensor unit and the electrical ground.

26. The medical device according to any one of claims 14 to 25, wherein: The electronic circuit board includes a first layer and a second layer positioned distally below the first layer; The first layer includes the conductive traces; and The second layer includes the conductive shield positioned distally below the conductive traces.

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