Electrosurgical Instruments

Abstract

An electrosurgical instrument for applying radio frequency (RF) electromagnetic (EM) energy and / or microwave frequency EM energy to biological tissue. The instrument includes an instrument tip having a planar body separating a first conductive element on a first surface from a second conductive element on a second surface. The instrument includes a coaxial feed cable including an inner conductor, an outer conductor coaxial with the inner conductor, and a dielectric separating the inner and outer conductors. The first conductive element includes a pattern configured to set an electrical length of the instrument tip to be greater than an electrical length of a reference instrument tip.

Description

[Technical field]

[0001] The present invention relates to an electrosurgical instrument for delivering electromagnetic energy (e.g., radio frequency energy and / or microwave energy) to living tissue for cutting tissue and / or for hemostasis (i.e., promoting blood clotting). For example, the present invention may be applied to instruments sized for insertion through the instrument channel of a standard surgical endoscope. [Background technology]

[0002] Surgical resection is a means of removing parts of organs from within the human or animal body. Such organs may be highly vascular. When tissue is cut (divided or transected), tiny blood vessels called arterioles are damaged or ruptured. Initial bleeding is followed by a clotting cascade in which blood is converted into a clot in an attempt to plug the bleeding point. During surgery, it is desirable for the patient to lose as little blood as possible, and therefore various devices have been developed in an attempt to provide a bleeding-free cut. Also, in the case of endoscopic surgery, bleeding is undesirable and needs to be managed in an appropriate manner, as blood flow can obscure the surgeon's view, which can prolong the operation and force the operation to be terminated and an alternative method, such as open surgery, used instead.

[0003] Electrosurgical generators are common in hospital operating rooms and are often used in open and laparoscopic procedures, and increasingly with surgical scoping devices such as endoscopes. In endoscopic procedures, electrosurgical accessories are typically inserted through lumens inside the endoscope. Considering the access channels applicable to laparoscopic procedures, such lumens are relatively small in diameter and longer in length.

[0004] Instead of sharp blades, it is known to use radio frequency (RF) energy to cut biological tissue. Cutting using RF energy works on the principle that as an electric current (aided by the ionic content of the cells and intercellular electrolytes) passes through the tissue matrix, heat is generated by the impedance to the flow of electrons across the tissue. In practice, the instrument is configured to apply an RF voltage across the tissue matrix that is sufficient to generate heat in the cells and evaporate the water in the tissue. However, this increased dryness can result in a loss of direct physical contact between the tissue and the instrument, especially adjacent to the RF emission area of ​​the instrument (which has the highest current density of the current path through the tissue). The applied voltage then appears as a voltage drop across a small cavity, which causes ionization within the cavity leading to plasma. Plasma has a very high volume resistivity compared to tissue. Energy supplied to the instrument maintains the plasma, i.e., completes the electrical circuit between the instrument and the tissue. Volatiles that enter the plasma can be evaporated, hence the perception of a tissue-dissociating plasma.

[0005] GB2 523 246 describes an electrosurgical instrument for applying RF electromagnetic energy and / or microwave frequency EM energy to biological tissue. The instrument includes a shaft insertable through an instrument channel of a surgical scoping device. At the distal end of the shaft is an instrument tip including a planar transmission line formed from a sheet of a first dielectric having first and second conductive layers on opposite surfaces thereof. The planar transmission line is connected to a coaxial cable carried by the shaft. The coaxial cable is configured to deliver either microwave energy or RF energy to the planar transmission line. The coaxial cable includes an inner conductor, an outer conductor coaxial with the inner conductor, and a second dielectric separating the outer conductor and the inner conductor, the inner and outer conductors extending beyond the second dielectric at a connection interface and overlapping opposite surfaces of the transmission line and in electrical contact with the first and second conductive layers, respectively. The instrument further includes a protective outer shell structure having a convex lower surface smoothly contoured in a direction away from the planar transmission line. The lower surface includes a longitudinally extending recessed channel formed therein. A retractable needle is mounted within the instrument and operable to extend through the recessed channel and protrude from the distal end of the instrument The needle can be used to inject fluid into the treatment zone before RF or microwave energy is applied.

[0006] The present invention has been devised in light of the above considerations. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention provides a development on the concepts described in GB2 523 246.

[0008] For example, it would be desirable to reduce the size of the instrument by making it thinner and / or shorter. A compact configuration offers several advantages. For example, a compact configuration may allow the instrument to be used in narrow scoping devices and / or in small biological structures, may allow the instrument to be more easily manipulated, and / or may help improve control and precision at the instrument tip.

[0009] However, it is difficult to reduce the size of the device while retaining its functionality.

[0010] For example, the ability to reduce the size of the instrument is limited by the size of the planar transmission line at the instrument tip. As explained in GB2 523 246, the overall length of the planar transmission line configuration is important in matching the impedance (or energy delivery) of (or from) the coaxial transmission line to (or within) the biological tissue. That is, the structure may form a quarter-wave impedance transformer or a half-wave resonator.

[0011] To efficiently transfer energy into tissue, the instrument tip may be configured with a physical length corresponding to a particular electrical length (i.e., number of wavelengths) at the desired energy frequency. For example, to provide efficient transfer at 5.8 GHz microwave energy, the physical length of the instrument tip may be selected to correspond to a half wavelength at that frequency (taking into account the dielectric constant of the material) so that the instrument tip acts as a half-wavelength resonator. However, because the physical length of the instrument tip is selected to provide a particular electrical length (i.e., corresponding to a particular number of wavelengths at the desired frequency), the physical length of the instrument tip cannot be shortened while retaining the desired electrical properties. Instead, as the physical length is shortened, the electrical length is also shortened, resulting in destructive reflections at the interface with biological tissue at the desired frequency (e.g., 5.8 GHz) and less efficient energy delivery through the instrument tip. Thus, the ability to reduce the size of the instrument tip has previously been limited by the need for efficient energy transfer.

[0012] The inventors have developed improved instruments that can effectively decouple the physical length of the instrument tip from its electrical length, and thus the instruments can provide efficient energy transfer into tissue at a given treatment frequency (e.g., microwave frequency), which can be the same frequency used in the prior art, while having different (e.g., smaller) dimensions than the prior art. [Means for solving the problem]

[0013] A first aspect of the present invention provides an electrosurgical instrument for applying radio frequency (RF) electromagnetic (EM) energy and / or microwave frequency EM energy to biological tissue, the instrument comprising: an instrument tip including a planar body separating a first conductive element on a first surface from a second conductive element on a second surface, the second surface facing away from the first surface; and a coaxial feed cable including an inner conductor, an outer conductor coaxial with the inner conductor, and a dielectric separating the inner and outer conductors, the coaxial feed cable for transmitting a working signal comprising an RF signal and / or a microwave signal. and wherein the inner conductor is electrically connected to a first conductive element and the outer conductor is electrically connected to a second conductive element to enable the instrument tip to receive a working signal, the first conductive element including a pattern configured to set an electrical length of the instrument tip to be greater than an electrical length of a reference instrument tip, the reference instrument tip including a reference flat body separating a reference first conductive element that completely covers the reference first surface from a reference second conductive element that completely covers the reference second surface, the reference second surface facing away from the reference first surface, and the reference flat body having the same shape and dimensions as the flat body.

[0014] By patterning the first conductive element in this manner, the instrument tip may be made smaller than those of the prior art while maintaining the ability to efficiently transfer working signals into tissue.

[0015] As used herein, the phrase "working signal" may refer to a signal for treating and / or diagnosing biological tissue. For example, the working signal may be a therapeutic signal for coagulating and / or ablating tissue. Additionally or alternatively, the working signal may be a diagnostic signal for diagnosing tissue, such as detecting tissue type based on how the tissue reflects energy. In one embodiment, the working signal is an RF EM signal and / or a microwave frequency EM signal.

[0016] As used herein, the phrase "electrical length" may refer to the length of the instrument tip calculated using the wavelength λ of the working signal, i.e., the phrase may refer to the length of the instrument tip that the working signal "sees." The electrical length may be calculated as a fraction or multiple of a wavelength. For example, to function as a half-wave resonator, the instrument tip may be approximately

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[0017] As used herein, the "reference instrument tip" is not a part of the electrosurgical instrument. Rather, the reference instrument tip is used for reference purposes to describe the advantages of the present invention compared to an instrument that is otherwise equivalent to the claimed electrosurgical instrument, but has a non-equivalent (reference) first conductive element that completely covers a comparable (reference) first surface of a comparable (reference) planar body.

[0018] As used herein, the phrase "pattern" may refer to the shape and / or size of the first conductive element. The pattern may be considered relative to the planar body, for example, such that the first conductive element has a shape and size that does not cover the entire first surface of the planar body. The pattern provides the instrument tip with a greater electrical length than would be provided by a reference first conductive element covering the entire (identical) reference first surface of a (identical) reference planar body. Thus, the pattern may be considered to include electrically extending sections that increase the electrical length of the instrument tip relative to the electrical length of the reference instrument tip. The pattern may include one or more voids (i.e., absence of conductive material) to increase the impedance of the conductive element, thereby increasing its electrical length.

[0019] Thus, embodiments may allow the physical size (e.g., length) of the instrument to be smaller than prior art configurations while maintaining the ability to efficiently deliver the same working signal (e.g., microwave frequency signal) to tissue because the pattern can increase the electrical length of the instrument, thereby offsetting any reduction in electrical length that would occur when reducing the physical size of the instrument.

[0020] As used herein, a "first surface" may refer to an upper surface of the instrument tip, and a "second surface" may refer to an underside of the instrument tip. The first and second conductive elements may each include a metallization layer formed on an opposing surface of the planar body. The planar body, the first conductive element, and the second conductive element may together be considered to form a planar transmission line. Other features of the electrosurgical instrument may be understood in light of GB2 523 246 and GB2 503 673, which are incorporated herein by reference.

[0021] Preferably, the instrument tip is configured as a resonator having an electrical length corresponding to a fraction or multiple (e.g., half a wavelength) of a wavelength at the desired frequency (e.g., at the frequency of the input microwave and / or RF energy). By providing an instrument tip that acts as a resonator at the desired frequency, unwanted reflections at the interface between the instrument tip and the coaxial cable and / or tissue can be reduced, thereby aiding in efficient delivery of energy from the coaxial cable into the tissue. Additionally, by providing an instrument tip that acts as a resonator, the instrument tip can ensure that the instrument tip transmits the working signal as a standing wave with a maximum at the distal end of the instrument tip, delivering the maximum amount of energy available to the tissue.

[0022] The present invention can be further understood in view of the following theory.

[0023] In general, the resonant frequency f of a resonant circuit is related to its inductance L and capacitance C as follows:

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[0024] To efficiently transfer the working signal into tissue, it is preferable for the instrument tip to have a resonant frequency close to or equal to the frequency of the working signal.

[0025] The resonant frequency of the circuit is also related to the wavelength of the signal, λ, the speed of light, c, and the dielectric constant, ε, as follows:

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[0026] By patterning the first conductive element, its inductance L and / or capacitance C may be changed (increased) to provide a desired electrical length without having to physically increase (i.e., lengthen and / or widen) the size of the instrument tip as a whole to increase the electrical length. Thus, the pattern may include one or more inductive and / or capacitive elements configured to electrically extend the instrument tip relative to a reference instrument tip to provide a desired electrical length even at a relatively small size.

[0027] As used herein, an "inductive element" may refer to any patterned conductive portion that has predominantly inductive (as opposed to capacitive) properties, such as a predominantly inductive contribution to impedance. An inductive element may also be referred to as an "inductive structure," an "inductive rack," or an "inductor."

[0028] As used herein, a "capacitive element" may refer to any conductive portion that has primarily capacitive (rather than inductive) properties, such as a primarily capacitive contribution to impedance. A capacitive element may refer to a portion of a capacitor (e.g., only a portion of a first conductive element) rather than the entire capacitor (which may further include a plane and a second conductive element). A capacitive element may also be referred to as a "capacitive structure" or a "capacitive plate."

[0029] Optionally, the inductive and capacitive elements may be visually distinct from one another. For example, the inductive elements may be relatively thinner than the capacitive elements to provide relatively high inductance and low capacitance. For example, the inductive elements may appear as relatively thin conductive tracks, whereas the capacitive elements may appear as relatively large conductive areas.

[0030] As will be further described with reference to Figure 2, when the instrument tip is configured as a resonator, certain regions of the instrument tip may be considered to act as inductors (high current, low electric field) or as capacitors (low current, high electric field). For example, in the case of a half-wave resonator, the proximal and distal ends of the instrument tip may act as capacitors and the center may act as an inductor.

[0031] Some structures may be considered to provide both capacitive and inductive effects, but may be characterized as "predominantly" capacitive or inductive. For example, a thin track in the center of a half-wave resonator may be a type of inductive element, since it may contribute primarily to inductance rather than capacitance. However, the thin track may also contribute (to a smaller extent) to capacitance due to an underlying second conductive element spaced from the first conductive element by a planar body. Conversely, a conductive plate in a proximal or distal region of a half-wave resonator may be a type of capacitive element, but in some embodiments may be modified to include cutouts (voids) to form loops (thinned tracks) that may also be considered to contribute to inductance. The capacitive contribution of the loop may be greater in the distal and / or proximal regions of the instrument tip than near the center.

[0032] Optionally, the pattern may be configured to set the impedance value of the instrument tip to match that of the coaxial cable. As used herein, impedance "matching" may allow for variation between 1 / 3 (33%) and 3 times (300%) of the desired value, or optionally between 70% and 140% of the desired value. Thus, the instrument may be highly tolerant to changing loads. Impedance matching may help improve the efficiency of energy transfer into the tissue. The pattern may include inductive and / or capacitive elements configured to provide impedance matching.

[0033] This can be further understood by considering the fact that the inductance L and capacitance C of a transmission line are related to its impedance Z as follows:

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[0034] Thus, the pattern of the first conductive element may be configured to provide a desired impedance Z (by varying its inductance L and / or capacitance C).

[0035] During use, the efficiency of energy transfer may be affected by impedance matching at the coaxial cable and impedance matching at the tissue, since reflections occur at both interfaces. However, tissue impedance may vary based on the type of tissue in contact or the amount (e.g., width) of tissue in contact. For example, tissue impedance may vary between about 20 and 300 ohms. Conversely, the impedance of the coaxial cable may be constant, e.g., 50 ohms. Therefore, it may be particularly useful to provide the instrument tip with an impedance that matches the impedance of the coaxial cable. In this way, signal reflections are cancelled out. For example, reflections from the junction between the tissue and the instrument tip cancel out reflections from the junction between the instrument tip and the tissue.

[0036] Advantageously, the instrument tip may also be configured as a resonator to improve energy transfer, as described above. By configuring the instrument tip as a resonator, the voltage at the distal end of the instrument tip is increased and the current is decreased, so that power is easily transferred from the coaxial line through the instrument tip and into the tissue. Thus, the resonant effect of the instrument tip may play a large role in the efficiency of energy transfer. Optionally, configuring the pattern to provide (or improve) an impedance match to the coaxial feed cable helps to further improve the efficiency of this energy transfer by effectively increasing the amplitude of the working signal in the instrument tip.

[0037] In general, tailoring the pattern to provide impedance matching can be particularly useful when trying to narrow the instrument tip (because narrowing the blade does not affect the resonant length but does affect the impedance), and configuring the pattern to provide a desired electrical length can be particularly useful when trying to shorten the active tip (because this affects the resonant length and impedance matching, and resonance can have a greater impact on energy delivery than impedance mismatch).

[0038] Optionally, the instrument tip is configured as a half wave resonator. Thus, the first conductive element may be patterned to provide an electrical length corresponding to a half wavelength of the working signal. An instrument tip configured as a half wave resonator may be approximated as having three regions: a proximal capacitive region, a central inductive region, and a distal inductive region. Thus, the first conductive element may be selectively patterned in one or more of these three regions to increase its impedance by utilizing the capacitive or inductive properties of different regions of the instrument tip to increase its electrical length.

[0039] In alternative embodiments, the instrument tip could be configured differently. For example, the instrument tip could be configured as a quarter wavelength impedance transformer. Alternatively, the instrument tip could be configured to resonate at another fraction or multiple of a wavelength, based on, for example, the desired frequency and size of the instrument.

[0040] Optionally, the instrument tip is configured to resonate at one of the following predetermined frequencies: 915 MHz, 2.45 GHz, 5.8 GHz, 14.5 GHz, 24 GHz. These frequencies may be particularly useful for treating biological tissue. For example, the instrument tip may be configured as a half-wave resonator at 5.8 GHz. To resonate at lower frequencies (e.g., 915 MHz), the instrument tip may include actual capacitors or inductors (also called "lumped components"), potentially significantly shortening devices that may be too long at these frequencies.

[0041] Optionally, the pattern forms at least one inductive element located in a central zone of the instrument tip. The phrase "central zone" may refer to a zone between a proximal zone of the conductive element (closer to the coaxial feed cable) and a distal zone of the conductive element (further away from the coaxial feed cable). For example, optionally, the instrument tip includes four quarters along its length (e.g., divided into four quarters, consisting of four quarters), with the central two quarters being joined together to form a central zone, and the pattern forms at least one inductive element in the central zone. In one embodiment, each quarter has substantially the same length (e.g., the quarters are equal quarters). The distal quarter may be referred to as the distal zone and / or the proximal quarter may be referred to as the proximal zone. The zones of the instrument tip are formed along the length of the planar body and may optionally further include spacer elements, if present (discussed further below).

[0042] The inductive element may be shaped to increase the impedance at the central zone, thereby making the instrument tip appear electrically extended. Providing the inductive element in the central zone may be particularly advantageous, as the central zone may then be the primary contributor to the inductance (rather than the capacitance) of the instrument tip when the instrument tip is configured as a half-wave resonator.

[0043] In a resonator, the current may be highest in the central zone of the conductive element and lowest at the edges, therefore, by placing an inductive element in the center, the inductance may have the greatest impact on improving efficient energy delivery, as inductance is related to the current.

[0044] In an alternative embodiment, a central zone of the first conductive element may include a capacitive element and inductive elements may be provided in different zones of the instrument tip (eg, a distal zone or a proximal zone).

[0045] The inductive element may include a thin track. As used herein, the phrase "thin track" may refer to a conductive section (region) that is relatively thinner than one or more other sections (regions) of the first conductive element (e.g., relatively thinner than the proximal and / or distal sections, e.g., relatively thinner than one or more capacitive elements). Optionally, the inductive element may include a first conductive region having a width that is 90% or less than the width (maximum width) of a second conductive region of the first conductive element, the second conductive region being located in the distal zone or the proximal zone. Similarly, the width of the first conductive region may also be 90% or less than the width (maximum width) of a third conductive region of the first conductive element, the third conductive region being located in the other of the distal zone or the proximal zone.

[0046] Optionally, the width of the first conductive region may be 80% or less, optionally 70% or less, optionally 60% or less, optionally 50% or less, optionally 40% or less, optionally 30% or less, optionally 20% or less, optionally 10% or less of the width of the second and / or third conductive region. Increasing the relative width difference between the conductive regions can increase their relative inductive and capacitive effects.

[0047] Optionally, the inductive element may include a conductive region having a width that is 90% or less of the maximum width of the body in the central zone. Optionally, the width may be 80% or less, optionally 70% or less, optionally 60% or less, optionally 50% or less, optionally 40% or less, optionally 30% or less, optionally 20% or less, optionally 10% or less of the maximum width of the body in the central zone. The absolute width of the inductive element may be selected to provide a desired impedance.

[0048] Thinning the conductive tracks is a particularly convenient way of increasing the inductance (and thus modifying its electrical length and / or impedance match) without having to increase the physical size of the device.

[0049] In some embodiments, the pattern may include a single inductive element in the central zone. For example, the pattern may include (only) a single inductive element extending along the longitudinal axis (e.g., central axis) of the instrument tip. The inductive element may connect a proximal conductive region (e.g., a capacitive plate) in the proximal zone of the active tip with a distal conductive region (e.g., a capacitive plate or conductive loop) in the distal zone of the active tip. Preferably, the inductive element has a length configured to prevent coupling of the working signal through a gap between the proximal and distal conductive regions in close proximity to the inductive element. For example, the gap may have a length (e.g., as measured between different conductive regions, such as the proximal and distal conductive regions) that is more than twice the thickness of the plane. For example, the plane may have a thickness of 0.5 mm and the gap(s) between the conductive regions may have a length of 1 mm or more. This is because the electromagnetic field may extend from below the conductive region a distance determined by the thickness of the plane (e.g., the first dielectric). When the fields of two conductive regions substantially overlap, coupling may occur between the conductive regions across the length of the gap. By providing a pattern with one or more gaps between inductive and / or conductive regions that are at least twice the thickness of the planar body, it can be ensured that the working signal is confined to following the path provided by the conductive element.

[0050] In an alternative embodiment, the gaps may be configured to have different lengths (eg, less than twice the thickness of the planar body) depending on the surrounding pattern.

[0051] As used herein, "longitudinal" may refer to a direction extending along the planar body between the proximal and distal ends of the instrument tip, and "lateral" may refer to a direction extending transversely across the planar body in a longitudinal direction. A "longitudinal" extension may include curvature or taper, e.g., if the planar body is curved or tapered, but may be considered to extend "predominantly" in the proximal / distal direction rather than transversely.

[0052] In some embodiments, the pattern may include, in addition to one or more transverse inductive elements, a longitudinal inductive element, e.g., a pair of inductive elements, that branch off (split off) from the longitudinal inductive element and extend laterally (e.g., transversely, perpendicularly) therefrom toward an edge of the planar body. The transverse inductive element may also be referred to herein as a "laterally extending arm." At or near the edge of the planar body, the pattern may again veer toward the longitudinal direction to provide a further pair of longitudinal inductive elements, each extending from a respective transverse inductive element toward the distal end of the instrument tip. The pair of transverse and longitudinal inductive elements may form part of a conductive loop (e.g., a D-shaped loop) at the proximal end of the instrument tip, with the inductive element forming a portion of the loop within a central zone of the instrument tip.

[0053] In some embodiments, the pattern may omit the (more proximal) first longitudinal inductive element mentioned above. Thus, one or more transverse inductive elements may extend directly from a capacitive plate in the proximal zone or (partially) in the central zone of the instrument tip. Thus, the pattern may include a conductive loop in the distal part of the instrument tip, which is connected (e.g., directly connected) to a capacitive element in the proximal part of the instrument tip. By omitting the central longitudinal track, a similar electrical length as above may be achieved, while making it possible to obtain an even smaller physical size.

[0054] The portion of the conductive loop in the central zone may effectively provide a pair (e.g., an opposing pair) of longitudinal (and optionally lateral) inductive elements, and thus may contribute significantly to the inductance of the instrument tip, since the conductive loop may include, for example, multiple inductive elements along opposite sides of the instrument tip, rather than just a single inductive element at the center of the instrument tip.

[0055] Optionally, the pattern includes an extension section configured to increase a physical length of the first conductive element relative to the physical length of the planar body. By increasing the physical length of the conductive element, the extension section may also effectively increase the length of the first conductive element seen by the working signal, thereby increasing the electrical length without having to also increase the physical length of the instrument tip (e.g., the planar body).

[0056] The extension section may include one or more conductive sections that are not aligned with the length (longitudinal) of the planar body. Optionally, the extension section may include a non-linear track (e.g., a thin track) for transmitting the working signal transversely to or away from the distal end of the instrument tip. The non-linear track may effectively provide a non-linear (indirect) path for the working signal (compared to a reference conductive element that may be considered to provide a "linear" or "direct" track at the distal end). For example, the extension section may include one or more deflections, i.e., one or more points where the conductive element (e.g., a thin track) changes direction (so as not to form a single straight line). For example, the extension section may include one or more deflections in the form of one or more bends, corners, and / or curves. The extension section may include one or more straight sections separated from another section by deflections.

[0057] Optionally, the extension section may have an undulating shape (e.g., serpentine, sinusoidal, wavy, zigzag, or square wave). Preferably, adjacent portions (e.g., adjacent undulations) of the extension section are spaced apart by gaps sized based on the wavelength of the working signal to be large enough to prevent (or reduce) signal coupling across the gap, thereby ensuring that input energy travels through the entire length of the extension section.

[0058] Alternatively or in combination, the extension section may include one or more branches extending along one or more peripheries of each of the planar bodies. Because the branches are disposed along the periphery of the distal zone, the branches may be useful for applying energy to tissue (e.g., to perform cutting and / or coagulation). The one or more branches may extend from a distal portion of the conductive element proximally toward (or into / through) the central zone to add extra physical length to (and thereby increase the electrical length of) the track formed by the first conductive element. The one or more branches may each terminate at a free end (in or near the central zone), e.g., the one or more branches may not be connected at their termination from any other conductive structure. This configuration may be considered to include both a capacitive element (e.g., in the distal zone) and an inductive element (e.g., in the central zone).

[0059] Optionally, the pattern forms at least one capacitive element in a distal quadrant of the instrument tip, which in this context may be referred to as a "distal capacitive element."

[0060] Optionally, the pattern forms at least one capacitive element in a proximal quadrant of the instrument tip, which in this context may be referred to as a "proximal capacitive element."

[0061] In a resonator (e.g., a half-wave resonator), the proximal and distal regions are where the electric field is highest and therefore may have the greatest effect on the capacitance. Therefore, capacitive elements in these regions may be particularly advantageous in these regions. Optionally, the pattern may include distal and proximal capacitive elements connected by a (central) inductive element.

[0062] In an alternative embodiment, the first conductive element may include a capacitive element in another region (eg, a central region).

[0063] Optionally, the or each capacitive element includes a conductive region having an area that fills most or all of the respective quadrant in which the capacitive element is formed, which may help to provide maximum capacitance within those regions to provide a desired electrical length and / or impedance match with the coaxial cable.

[0064] Optionally, the distal capacitive element extends along one or more peripheries within a distal quadrant of the instrument tip (e.g., along a curved edge of the instrument tip), such that the distal capacitive element may be in intimate contact with tissue to treat the tissue.

[0065] Optionally, a proximal section of the first conductive element (e.g., a proximal capacitive element) may be spaced from one or more side edges of the planar body in a proximal quadrant of the instrument tip, such that the proximal section of the first conductive element may avoid interaction with tissue so that energy can be transferred primarily to tissue at the distal end of the instrument tip.

[0066] Optionally, the first and / or second conductive elements may be set back from the side edge of the planar body in the proximal region of the instrument tip (e.g., the proximal quadrant of the instrument tip) along the proximal 3.5 mm of the tip, for example, a distance of at least 0.1 mm, optionally at least 0.15 mm, optionally at least 0.2 mm. This may help to ensure that the RF energy does not cut tissue in the proximal region of the instrument tip, and that instead the RF energy is dispersed away from the distal tip of the planar body. This may have a similar effect with microwave energy, although to a lesser extent.

[0067] Optionally, the pattern includes conductive loops surrounding non-conductive regions, the conductive loops being located in the distal two quadrants of the instrument tip. The non-conductive regions may also be referred to as "cutouts," "non-capacitive regions," "voids," or "hollow" regions of the capacitive plate. By configuring the pattern as conductive loops within the two distal quadrants (e.g., rather than a conductive plate covering the entire two distal quadrants), the inductance and capacitive properties can be further tailored to provide a desired electrical length and / or impedance matching. In particular, the cutouts can be used to reduce capacitance, since they reduce the area of ​​the conductive elements. Furthermore, the loops can increase the inductance of the instrument tip, since they can be considered as thin tracks (parts of which may be located in the central region, i.e., the second most distal). Thus, the loops can be considered to include both capacitive and inductive elements.

[0068] Optionally, the conductive loop is configured to extend along one or more edges of the planar body in the distal zone of the instrument tip. The loop may thus be used to affect, treat or diagnose tissue in a manner similar to the distal capacitive element described above. As an added advantage, the loop may also provide a clearer and more visible working surface for the clinician compared to, for example, a solid capacitive plate.

[0069] Optionally, the pattern is symmetric about a longitudinal axis of the instrument tip. "Longitudinal axis" refers to an axis extending from a proximal zone to a distal zone of the instrument tip. By providing a first conductive element that is symmetric across this axis, the instrument tip may provide a relatively symmetrical energy distribution across both sides of the instrument. Thus, the instrument may be more convenient to use, since the clinician does not need to worry about how to orient the device to best transfer energy into the tissue.

[0070] The second conductive element of the instrument tip may be configured similarly to the first conductive element, e.g., having the same pattern as the first conductive element, so that, for example, the first and second conductive elements overlap one another. Alternatively, the second conductive element may be configured differently from the first conductive element. For example, the second conductive element may include a substantially uniform metallization across the second surface of the planar body. The uniform metallization may cover substantially all of the planar body (e.g., its underside). Thus, the second conductive element may cover most or the entire second surface of the planar body. This may provide a relatively convenient structure for the second surface of the planar body.

[0071] Optionally, the instrument tip may include a spacer element proximal to the planar body. The inner conductor may be electrically connected to the first conductive element by a proximal transmission line on the spacer element. The first conductive element and / or the second conductive element may be set back from the proximal end of the spacer element by a distance of optionally at least 0.2 mm, optionally at least 0.3 mm, optionally at least 0.4 mm, optionally at least 0.5 mm, optionally at least 0.6 mm. Optionally, the spacer element may be devoid of the first conductive element. By setting back the first and / or second conductive elements from the proximal edge of the spacer element, this may help to ensure that the first (upper / top) conductive layer is separated from the outer conductor of the coaxial cable.

[0072] Optionally, the spacer element may be chamfered (as described below with respect to the third aspect). The chamfer may serve to reduce the extent to which the proximal transmission line protrudes beyond the spacer element, thereby allowing the size of the instrument to be reduced. The instrument tip (e.g., the pattern of the first conductive element) may be configured to take into account the effect that the chamfer may have on impedance and / or electrical length. For example, the shape and length of the junction between the proximal transmission line and the first conductive element may be configured (patterned) to improve microwave performance, as it is the reflection from this point that ideally counterbalances the reflection from the distal tip of the instrument tip, improving efficiency. For example, the size and shape of the proximal portion of the first conductive element may be patterned to provide improved electrical length and / or impedance matching.

[0073] The spacer element may be integrally formed with the planar body or may be otherwise attached to a proximal edge of the planar body. The spacer element may comprise the same material as the planar body.

[0074] Optionally, the instrument tip may have a rectangular shape. Optionally, the instrument tip may have a non-rectangular shape. For example, the distal end of the planar body may be tapered (e.g., tapered or curved in the distal direction). For example, the width of the instrument tip in the plane of the planar body may progressively decrease as one moves in the distal direction. This may be useful to aid the cutting function of the instrument tip. However, a curved distal end may effectively reduce the electrical length of the instrument tip, as compared to, for example, a rectangular planar body having the same length and width, since capacitance is thereby effectively removed from the distal end of the instrument. This is explained in more detail in GB2 503 673. To compensate for this reduction in electrical length, prior art configurations enlarged the physical size of the instrument. Advantageously, the instrument tip of the present invention may be smaller than those configurations, as the pattern of the first conductive element may help to offset the electrically shortening effect of the curved distal end. Thus, the planar body may be advantageously shorter than those of the prior art, while retaining other functions.

[0075] In some embodiments, the pattern may only partially offset the electrically shortening effect of the curved distal tip, so that the physical length of the instrument tip may be shorter than that of the prior art, but the physical length may still be longer than the electrical length.

[0076] In some embodiments, the pattern may (completely) counteract the effect of a curved distal end (or other electrically shortening pattern), thus making the physical length of the instrument equal to its electrical length.

[0077] In some embodiments, the pattern may counteract the effect of a curved distal tip (or other electrically shortening pattern), such that the physical length of the instrument tip may be less than its electrical length.

[0078] For example, in a configuration having one or more electrically extending sections and one or more electrically shortening sections, the one or more electrically extending sections can be configured to offset and / or overcome the effect of the electrically shortening sections on the electrical length.

[0079] Thus, the pattern may set the electrical length of the instrument tip to be equal to or greater than the physical length of the instrument tip. Optionally, two or more quadrants of the electrosurgical instrument may be joined to provide an electrical length longer than its physical length.

[0080] Optionally, the instrument tip may have a maximum length of 10.0 mm or less. For example, the instrument tip may have a maximum length of less than 9 mm. For example, the instrument tip may have a maximum length of 8 mm. In this context, the length of the instrument tip may refer to the length of the planar body, optionally further including spacer elements, if present. Thus, the planar body may be made relatively shorter than previous configurations, and may be shorter than its electrical length.

[0081] Optionally, the planar body may have a maximum width of 1.9 mm or less. For example, the planar body may have a maximum width of 1.8 mm. Thus, the planar body may be relatively narrower than previous configurations. Narrowing the device may cause impedance matching variations, for example, by reducing the capacitance of the conductive elements. However, as described above, the pattern may be configured to take these variations into account, for example, to provide an impedance match with a coaxial cable (e.g., a 50 ohm impedance). The planar body may include width variations along its length (e.g., have a tapered distal region).

[0082] Preferably, the planar body may have a length greater than its maximum width.

[0083] Preferably, the plane may have a maximum thickness of 0.5 mm or less.

[0084] The first conductive element may have a height of more than a few skin depths. The required height is proportional to the inverse square root of the frequency. For example, for a conductive element made of copper, the first conductive element may have a height of at least 5 microns (0.005 mm) for a 5.8 GHz working signal, and at least 0.013 mm for a 915 MHz working signal. Optionally, the first conductive layer may have a height of 0.05 mm or less, optionally 0.03 mm or less.

[0085] Preferably, the coaxial cable has an outer diameter of 2 mm or less, more preferably 1.8 mm or less, and even more preferably 1.6 mm or less.

[0086] Optionally, the instrument tip may be configured to deliver fluid into the biological tissue (e.g., using a needle or other method). Alternatively, optionally, the instrument tip may not be configured to deliver fluid into the biological tissue. For example, the instrument tip may be configured to deliver energy (only) into the tissue.

[0087] Optionally, the instrument tip may include a nozzle at its distal end to deliver pressurized fluid directly into the biological tissue. The fluid may be injected into the biological tissue to swell the tissue prior to treatment with the working signal (e.g., to cut the tissue). By including a nozzle to deliver pressurized liquid, the surgical instrument may not require a needle to pierce the tissue. For example, the fluid pressure may be high enough to pierce or penetrate the biological tissue (e.g., mucosal and / or submucosal tissue). Instead, the pressurized fluid may be used to irrigate or lift tissue in an area that has already been pierced (e.g., by another instrument not connected to the second fluid channel or another needle on the surgical instrument).

[0088] The nozzle may be positioned and shaped to avoid inadvertently piercing or otherwise damaging tissue. For example, the nozzle may have a relatively blunt or blunt (non-sharp) fluid outlet for injecting pressurized fluid into tissue. For example, the nozzle may be cylindrical and / or have a round (e.g., circular) outlet. The nozzle may be fixed (e.g., non-retractable) relative to other elements of the instrument tip (e.g., relative to a planar body). The nozzle may have an opening that is flush with a surface of the instrument tip (e.g., a distal surface of the instrument tip) or may have an opening that is positioned proximal to the distal surface of the instrument tip so that it does not protrude from the instrument.

[0089] By providing a nozzle at the distal end of the instrument tip for delivering pressurized fluid directly into the living tissue, the instrument may not require a retractable needle to pierce and deliver fluid into the living tissue. Furthermore, the flexible shaft connected to the instrument tip may not require a push rod, control wires, or other means to control the deployment of such a retractable needle at the instrument tip. Thus, the instrument may have a relatively simpler construction and smaller profile than prior art instruments that require a retractable needle.

[0090] In some configurations, in addition to (or instead of) the conductive pattern, the instrument tip may be modified in other ways to provide suitable electrical length and / or impedance matching. For example, capacitance could be modified by modifying the height of the planar body (thereby changing the distance between the first conductive element and the second conductive element). Alternatively, or in combination, inductance could be modified by or by changing the magnetic properties of the planar body. For example, in some embodiments, the planar body may include (e.g., consist of) a dielectric (e.g., alumina). Additionally or alternatively, in some embodiments, the planar body may include a ferrite material (e.g., in at least one quadrant of the planar body, e.g., in the central zone). This may provide a change in inductance without the need for thin conductive tracks.

[0091] Another aspect of the present invention provides an electrosurgical instrument for applying radio frequency (RF) electromagnetic (EM) energy and / or microwave frequency EM energy to biological tissue, the instrument including an instrument tip including a planar body separating a first conductive element on a first surface from a second conductive element on a second surface, the second surface facing away from the first surface, and a coaxial feed cable including an inner conductor, an outer conductor coaxial with the inner conductor, and a dielectric separating the inner conductor and the outer conductor, the coaxial feed cable for transmitting a working signal including an RF signal and / or a microwave signal, the inner conductor electrically connected to the first conductive element and the outer conductor electrically connected to the second conductive element to enable the instrument tip to receive the working signal, and the first conductive element including a pattern configured to set an electrical length of the instrument tip to be equal to or greater than a physical length of the instrument tip.

[0092] Further features and advantages presented with respect to the first aspect are equally applicable with respect to the other aspects and are restated below.

[0093] The second aspect of the present invention presents an alternative solution for providing a shorter instrument tip. Like the first aspect, the second aspect also provides a first conductive element that is patterned to reduce destructive reflections at the end of the conductive element, thereby ensuring efficient energy transfer into the tissue. However, the second aspect achieves this in a different manner than the first aspect.

[0094] A second aspect of the invention provides an electrosurgical instrument for applying radio frequency (RF) electromagnetic (EM) energy and / or microwave frequency EM energy to biological tissue, the instrument comprising: an instrument tip including a planar body separating a first conductive element on a first surface from a second conductive element on a second surface, the second surface facing away from the first surface; and a coaxial feed cable including an inner conductor, an outer conductor coaxial with the inner conductor, and a dielectric separating the inner conductor and the outer conductor, for transmitting a working signal comprising an RF signal and / or a microwave signal, the inner conductor being electrically connected to the first conductive element and the outer conductor being electrically connected to the second conductive element to enable the instrument tip to receive the working signal, the first conductive element including an elongated track having a peripheral section for transmitting the working signal around a periphery of a distal region (e.g., the planar body) of the instrument tip for contacting tissue. In one embodiment, the peripheral section has a physical length greater than the physical length of the distal region (e.g., in a direction aligned with a longitudinal axis of the instrument tip).

[0095] As used herein, the phrase "distal region" may refer to the most distal section (e.g., planar body) of the instrument tip, such as, for example, the distal 10%, optionally at least (or about) 20%, optionally at least (or about) 30%, optionally at least (or about) 40%, optionally at least (or about) 50% of the length of the instrument tip.

[0096] As used herein, the phrase "around the periphery" may refer to a path that is disposed on top of and continues in a direction along (around) the periphery of the distal region. This may be distinguished from a track that completely covers the first surface and instead transmits a working signal directly from the proximal end of the instrument tip to the distal end of the instrument tip (e.g., in a direction aligned with the longitudinal axis of the instrument tip) without transmitting a signal around the periphery.

[0097] Because the peripheral section transmits the working signal around the periphery, the peripheral section of the conductive element can have a physical length (e.g., in a direction aligned with the longitudinal axis of the instrument tip) that is greater than the physical length of the distal region of the first surface of the planar body.

[0098] By providing an elongated track that extends (at least partially) around the periphery of the distal region of the planar body, the energy density of the track for contacting tissue may be increased (e.g., compared to a reference first conductive element that covers the entire first surface of a (comparable) reference planar body). Furthermore, the physical length of the track in contact with tissue may be increased compared to a reference first conductive element. Thus, the elongated track may help to efficiently transfer energy into tissue by effectively facilitating energy transfer (i.e., loss) from the track into the surrounding tissue as the working signal travels along the peripheral section.

[0099] In contrast to the prior art configurations, the first conductive element of the second embodiment may not configure the instrument tip as a resonator. Instead, the conductive element may configure the instrument tip as a lossy transmission line for the working signal. "Lossy transmission line" is a term in the art and may mean a transmission line configured to promote signal loss upon contact with a load (e.g., tissue). A lossy transmission line may be configured to lose energy at a fairly steady rate along its length upon contact with tissue and not be particularly frequency sensitive, whereas a resonator may be configured to lose energy to tissue at certain points along its length and not others, for example, to lose energy to tissue at the distal end but not halfway along the blade, and have a resonant frequency designed for which it works best.

[0100] By patterning the first conductive element in this manner (e.g., the pattern is in the form of an elongated track), as the working signal travels along the peripheral section and contacts tissue, energy may be efficiently absorbed into the tissue, thereby reducing the amplitude of the signal along the length of the peripheral section. Thus, the amplitude may be reduced to a degree that mitigates or reduces any reflections (and thus destructive interference) at the terminations of the conductive elements. As a result, the pattern may allow the instrument tip to have a different (e.g., smaller) size than the prior art, while also avoiding the effects of destructive interference that would occur when reducing the size of prior art resonant instrument tips.

[0101] The length and / or width of the first conductive element (e.g., the elongated track or peripheral section) may be modified (patterned) to further tailor these effects, for example, by increasing its inductance and / or impedance, and to provide desired signal loss characteristics along the length of the elongated track. For example, the elongated track may have a length and width configured such that by the time the working signal reaches the termination of the conductive element, its amplitude is significantly reduced (e.g., less than 10%, optionally less than 5%, optionally zero, of the input amplitude at the input (proximal) end of the first conductive element), thereby significantly reducing any reflections and resulting interference at the termination of the conductive element.

[0102] Thus, the elongated track (i.e., peripheral section) may be relatively long and / or narrow compared to the length and / or width of the planar body. Optionally, the elongated track (e.g., peripheral section) may have a width that is less than 30%, optionally less than 20%, optionally less than 10% of the maximum width of the planar body (e.g., distal region).

[0103] A narrow width may be particularly advantageous in the peripheral section of an elongated track, since narrowing the track in the peripheral section increases the power density throughout the track, thereby ensuring that more power is closer to the tissue and therefore can be transferred from the instrument to the tissue. In other words, the narrower the track, the more the power of the working signal is distributed over a narrower width of the track. By providing a narrow peripheral section (which is the distal periphery for contacting the tissue), a larger amount of power can be placed closer to the end of the instrument (rather than distributed over a wider track). Thus, by providing a narrow peripheral section, a larger amount of power can be efficiently transferred into the tissue, thereby further reducing the signal amplitude in the track and reducing the possibility of any reflections at its end. The track width may be configured so that the power is transferred to the tissue at an optimal rate, neither all of it is used up in the first few mm, nor so much is left at the end to be reflected.

[0104] Optionally, the elongate track may also have a narrow proximal section, e.g., having a width less than 50%, optionally less than 40%, optionally less than 30%, optionally less than 20%, optionally less than 10% of the maximum width of the planar body.

[0105] The width of the elongate track (e.g., the peripheral section) may be substantially uniform, but may vary along its length, for example to account for bends and corners along the elongate track. Thus, the width of the peripheral section may have slight deviations, for example within ±10%, optionally within ±5%.

[0106] For example, the peripheral section may extend around at least the distal 30% of the planar body, optionally at least the distal 40% of the planar body, and optionally at least the distal 50% of the planar body. In other words, the distal region may cover the distal 30% of the length of the planar body, optionally the distal 40% of the length of the planar body, and optionally the distal 50% of the length of the planar body, and the peripheral section may extend around the entirety of the distal region. By extending the elongated track to extend around a relatively large distal region, the amount of energy transfer into tissue can be further increased.

[0107] Optionally, the distal end of the planar body may be curved and the peripheral section may extend around most or all of the curved distal end, which may provide a useful blade for treating tissue.

[0108] The elongate track may include a proximal section for connecting the coaxial feed cable to the perimeter section. Optionally, the proximal section may be set back (spaced apart) from one or more side edges of the planar body in a proximal region (e.g., proximal quarter or half) of the instrument tip (e.g., planar body). As with the first embodiment, this may help ensure that energy is transferred into the tissue primarily from the distal (rather than the proximal) end of the instrument tip.

[0109] The proximal section may include an inductive element (e.g., a narrow track) that may include any of the features described above with respect to the first embodiment. The proximal section may have a capacitive element (or an enlarged proximal end) for connection to the coaxial feed cable. The capacitive element may include any of the features described above with respect to the first embodiment. The inductive and / or capacitive element may be sized to improve impedance matching to the coaxial cable and / or tissue (e.g., relative to a reference conductive element covering all or most of the proximal region of the planar body).

[0110] Optionally, most or all of the first conductive element may be formed of an elongated track. The first conductive element may include one or more elements configured similarly to the inductive elements described in the first embodiment.

[0111] Optionally, the elongated track may further include an extension section to further increase the physical length of the elongated track relative to the physical length of the planar body. Thus, the extension section may serve to increase the length (and therefore loss) through the transmission line without requiring additional physical length to be added to the planar body.

[0112] The extension section may be considered to be the "second" extension section and the perimeter section may be considered to be the "first" extension section, since each section may be shaped to increase the physical length of the elongated track relative to the planar body. The extension sections may also be referred to as "redundant sections" or "nonlinear sections."

[0113] The extension section may be configured similarly to the extension section described in the first embodiment. For example, similar to the extension section described in the first embodiment, the extension section may include one or more deflections (e.g., waves, zigzags, branches) to cause the elongated track to change direction along the planar body.

[0114] The extension may have a similar width as the peripheral section, for example, the elongate track may have a width that is less than 40%, optionally less than 40%, optionally less than 30%, optionally less than 20%, optionally less than 10% of the maximum width of the planar body.

[0115] Optionally, the extension section may be disposed between the proximal end of the conductive element (e.g., the end connected to the inner conductor) and the peripheral section. For example, the elongate track may have a wavy or zigzag shape in a proximal and / or central region of the instrument tip.

[0116] Optionally, the extension section may be disposed between the peripheral section and the terminal end of the conductive element, This configuration may help ensure that the signal first contacts tissue along the peripheral section to treat the tissue before additional loss is introduced along the extension section.

[0117] As used herein, the "terminus" of a conductive element refers to the end of the conductive element seen by the working signal when the conductive element is not in contact with tissue. The terminus may be different from the distal end of the conductive element, as the terminus may optionally not be located at the distal end of the instrument tip.

[0118] As used herein, the phrase "between" may mean that the extension section is electrically between two sections (e.g., the peripheral section and the termination) as seen by a signal traveling along the electrical element. This may not require that the extension section be physically between the peripheral section and the termination. For example, the extension section and the termination may each be physically located between two sides of the peripheral section, e.g., by forming a spiral with the peripheral section, with an outer section of the spiral forming the peripheral section and an inner section of the spiral forming the extension section and the termination. The inner section may include a linear section (prong) that extends longitudinally along the center of the planar body.

[0119] Optionally, the extension section may be located at a distal region of the instrument tip. For example, the extension section may be located at the distal half of the instrument tip. For example, the extension section may be located at a curved tip of the instrument tip. Optionally, the terminal end may also be located at a distal region of the planar body. Locating the extension section and / or terminal end at a distal region of the instrument tip may help provide a desired energy distribution by directing energy towards tissue at the distal end of the blade.

[0120] Optionally, the peripheral section and the extension section may together form a spiral, for example, as described above, in the distal region of the planar body. The spiral may provide a relatively convenient and compact configuration for providing the extension section that is physically located within the peripheral section. The spiral may be curved or may have sharp edges (e.g., corners).

[0121] Preferably, adjacent sections of the spiral (e.g., the peripheral section and the additional extension section) may be spaced apart with a gap sized to prevent microwave coupling between the sections. This may help to ensure that the working signal travels the full physical length of the conductive track. For example, adjacent sections of the spiral may be separated by a gap having a width less than 40%, optionally less than 30%, optionally less than 20%, optionally less than 10% of the maximum width of the planar body.

[0122] Optionally, the gaps may have the same width as the elongated tracks. For example, in one embodiment, the elongated tracks may have a substantially uniform width of about 20% of the maximum width of the distal region of the planar body, and the gaps between adjacent sections of the tracks may also have a substantially uniform width of about 20% of the maximum width of the distal region of the planar body. This configuration may allow for the provision of a convenient, evenly spaced spiral configuration that balances the width of the tracks with the width of the gaps.

[0123] Optionally, the first conductive element is configured to match the impedance of the coaxial feed cable. For example, similar to the first embodiment, the first conductive element may include an inductive and / or capacitive element configured to closely match the impedance of the coaxial feed cable, which may serve to further improve the efficiency of the energy transfer. For example, the coaxial feed cable may have an impedance of 50 ohms. The conductive and / or inductive elements may be configured in a manner similar to any of the conductive and / or inductive elements of the first embodiment to provide a desired impedance at a desired dimension.

[0124] The invention of the second aspect may also include other features that may be the same or similar to the features described in relation to the first aspect.

[0125] For example, optionally, the second conductive element may cover most or all of the second surface of the planar body.

[0126] Optionally, the instrument tip may include a spacer element proximal to the planar body. The spacer element may be chamfered and may be electrically connected to the first conductive element by a proximal transmission line over the chamfered spacer element.

[0127] Optionally, the instrument may have the same dimensions as those described above with respect to the first aspect. Optionally, the instrument tip has a length of 10.0 mm or less. Optionally, the planar body has a width of 1.9 mm or less.

[0128] A third aspect of the present invention provides an instrument tip with improved connections to the instrument tip. In particular, the third aspect presents an electrosurgical instrument for applying radio frequency (RF) electromagnetic (EM) energy and / or microwave frequency EM energy to biological tissue, the instrument comprising an instrument tip including a planar body separating a first conductive element on a first surface from a second conductive element on a second surface, the second surface facing away from the first surface, and a coaxial feed cable including an inner conductor, an outer conductor coaxial with the inner conductor, and a dielectric separating the inner conductor and the outer conductor, for transmitting a working signal comprising an RF signal and / or a microwave signal, the inner conductor being electrically connected to the first conductive element and the outer conductor being electrically connected to the second conductive element to enable the instrument tip to receive the working signal, the instrument tip further comprising a spacer element proximal to the planar body, the spacer element being chamfered.

[0129] Advantageously, the inventors have discovered that a chamfered spacer element serves to provide a stronger, less fragile connection between the coaxial cable and the planar body of the instrument tip. A chamfered spacer element may also provide several additional advantages, for example, as described elsewhere herein (e.g., with respect to the first aspect).

[0130] The outer conductor and / or dielectric of the coaxial feed cable may terminate along the spacer element such that a distal end of the outer conductor and / or dielectric of the coaxial feed cable is disposed on the spacer element, and the inner conductor of the coaxial cable may protrude beyond the distal end of the outer conductor and / or dielectric of the coaxial feed cable, beyond the spacer element, and onto the planar body to connect with the first conductive element.

[0131] The electrosurgical instrument of the third aspect may optionally include any feature(s) described above with respect to the first and / or second aspects. For example, the spacer elements may optionally include any feature(s) described above with respect to the first and / or second aspects. Optionally, the first conductive elements may be patterned in any manner described in the first or second aspects. Alternatively, the first conductive elements may be patterned in different ways to provide different EM characteristics while retaining the benefits of a chamfered spacer element.

[0132] The present invention includes combinations of the aspects and preferred features described herein except where such combinations are clearly unacceptable or clearly avoided.

[0133] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Exemplary embodiments illustrating the principles of the present invention are now described with reference to the accompanying drawings, in which like numerals refer to like elements and in which: FIG. [Brief description of the drawings]

[0134] [Figure 1] 1 is a schematic diagram of a complete electrosurgical system in which the present invention may be applied; [Diagram 2] 1 is a graph showing the variation of electric field and current over the length of a half wave resonator. [Diagram 3] 3A-3C are top, side, and bottom views, respectively, of a prior art instrument tip. [Figure 4] FIG. 1 is a top view of an instrument tip according to a first embodiment of the present invention. [Diagram 5] FIG. 5 is a perspective view of the instrument tip of FIG. 4 connected to a coaxial cable. [Figure 6] FIG. 1 is a top view of an exemplary reference instrument tip for comparison with the first embodiment. [Figure 7] FIG. 1 is a scale drawing showing a side-by-side comparison of a prior art instrument tip and the instrument tip of the first embodiment. [Figure 8A] FIG. 2 is a perspective view of the instrument tip of the first embodiment with the distal tip inserted into tissue. [Figure 8B]FIG. 8B is a top view of the power loss density around the instrument tip in the position of FIG. 8A. [Figure 8C] 8B is a graph of scattering parameters measured with the configuration of FIG. 8A. [Figure 9A] FIG. 13 is a perspective view of a first instrument tip with only one lateral half of the distal tip inserted into tissue. [Figure 9B] 9B is a graph of scattering parameters measured with the configuration of FIG. 9A. [Figure 10] FIG. 11 is a scale drawing showing a top view of an instrument tip according to a second embodiment of the present invention. [Figure 11] FIG. 11 is a perspective view of the instrument tip of FIG. [Figure 12A] FIG. 13 is a top view of the instrument tip of the second embodiment with only the distal-most section inserted into tissue. [Figure 12B] FIG. 12B is a top view of the power loss density around the instrument tip of the configuration of FIG. 12A. [Figure 12C] 12B is a graph of scattering parameters measured with the configuration of FIG. 12A. [Figure 13A] 12B is a perspective view of the instrument tip of the second embodiment further inserted into the tissue of FIG. 12A in a position similar to FIG. 8A. [Figure 13B] FIG. 13B is a top view of the power loss density around the instrument tip in the position of FIG. 13A. [Figure 13C] 13B is a graph of scattering parameters measured with the configuration of FIG. 13A. [Figure 14A] FIG. 9B is a perspective view of the instrument tip of the second embodiment in a position similar to that of FIG. 9A with only one lateral half of the distal tip inserted into tissue. [Figure 14B] FIG. 14B is a top view of the power loss density around the instrument tip of the configuration of FIG. 14A. [Figure 14C] 14B is a graph of scattering parameters measured with the configuration of FIG. 14A. [Figure 15] FIG. 11 is a scale drawing showing a top view of an instrument tip according to a third embodiment of the present invention. [Figure 16] FIG. 13 is a perspective view of the active tip of the instrument tip of the third embodiment. [Figure 17A] FIG. 13 is a perspective view of the instrument tip of the third embodiment with only the distal-most section inserted into tissue. [Figure 17B] FIG. 17B is a top view of the power loss density around the instrument tip of the configuration of FIG. 17A. [Figure 17C] 17B is a graph of scattering parameters measured with the configuration of FIG. 17A. [Figure 18A] 17A is a perspective view of the instrument tip of the third embodiment further inserted into the tissue of FIG. 17A in a position similar to FIGS. 8A and 13A. [Figure 18B] FIG. 18B is a top view of the power loss density around the instrument tip of the configuration of FIG. 18A. [Figure 18C] 18B is a graph of scattering parameters measured with the configuration of FIG. 18A. [Figure 19A] 14A and 14B are top views of the instrument tip of the third embodiment with only one lateral half of the distal tip inserted into tissue in a position similar to that of FIGS. 9A and 14A. [Figure 19B] 19B is a graph of scattering parameters measured with the configuration of FIG. 19A. [Figure 20] FIG. 13 is a top view of an instrument tip according to a fourth embodiment of the present invention. [Figure 21] FIG. 13 is a scale drawing showing a top view of an instrument tip according to another aspect of the present invention. [Figure 22A] 22 is a perspective view of the instrument tip of FIG. 21 inserted into tissue in a position similar to FIGS. 8A, 13A, and 18A. FIG. [Figure 22B] FIG. 22B is a top view of the power loss density around the instrument tip of the configuration of FIG. 22A. [Figure 22C] 22B is a graph of scattering parameters measured with the configuration of FIG. 22A. [Figure 23A] 22A-22D are top views of power loss density around the tip of the instrument of FIG. 21 when inserted at various different locations within tissue. [Figure 23B] 22A-22D are top views of power loss density around the tip of the instrument of FIG. 21 when inserted at various different locations within tissue. [Figure 23C]22A-22D are top views of power loss density around the tip of the instrument of FIG. 21 when inserted at various different locations within tissue. [Figure 23D] 22A-22D are top views of power loss density around the tip of the instrument of FIG. 21 when inserted at various different locations within tissue. [Figure 23E] 22A-22D are top views of power loss density around the tip of the instrument of FIG. 21 when inserted at various different locations within tissue. [Figure 24A] FIG. 13 is a perspective view of an embodiment of an instrument tip with only the most distal tip inserted into tissue. [Figure 24B] 24B is a graph of scattering parameters measured with the configuration of FIG. 24A. [Figure 25A] FIG. 24B is a perspective view showing the instrument tip of FIG. 24A being inserted further into tissue. [Figure 25B] 25B is a graph of scattering parameters measured with the configuration of FIG. 25A. [Figure 26] FIG. 1 is a top view of an instrument tip according to one embodiment of the present invention. [Figure 27] 27 is a graph of the scattering parameters measured for the instrument tip of FIG. 26. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0135] Aspects and embodiments of the present invention will now be described with reference to the accompanying drawings. Further aspects and embodiments will be apparent to those skilled in the art. All documents mentioned in this text are incorporated herein by reference.

[0136] 1 is a schematic diagram of a complete electrosurgical system 100 that can selectively deliver any or all of RF energy, microwave energy, and fluid, such as saline or hyaluronic acid, to the distal end of an invasive electrosurgical instrument. The system 100 includes a generator 102 for controllably delivering electromagnetic (EM) energy. In this embodiment, the EM energy includes RF EM energy and / or microwave frequency EM energy. Suitable generators for this purpose are described in WO2012 / 076844, which is incorporated herein by reference.

[0137] The generator 102 is connected to an interface joint 106 by an interface cable 104. The interface joint 106 is also connected to receive a supply of pressurized fluid from a fluid delivery device 108 via a fluid supply cable 107. The function of the interface joint 106 is to combine the inputs from the generator 102 and the fluid delivery device 108 to a single flexible shaft 112 that extends from a distal end of the interface joint 106. It will be appreciated that the shaft 112 may form part of the interface joint 106.

[0138] The flexible shaft 112 is insertable through the entire length of the instrument (working) channel of the surgical scoping device 114. A torque transfer unit 116 may be attached to the proximal length of the shaft 112 between the interface joint 106 and the surgical scoping device 114. If present, the torque transfer unit 116 engages the shaft and allows it to rotate within the instrument channel of the surgical scoping device 114.

[0139] The flexible shaft 112 has an electrosurgical instrument tip 118 shaped to pass through an instrument channel of a surgical scoping device 114 (e.g., an endoscope) and protrude (e.g., inside the patient) at the distal end of the instrument channel. The instrument tip includes an active tip for delivering RF EM energy and / or microwave EM energy into living tissue and an aperture for delivering pressurized fluid (e.g., saline, Gelofusine, and / or hyaluronic acid with added marker dyes). These combined techniques provide a unique solution for cutting and destroying unwanted tissue and the ability to seal blood vessels around the target area. By applying pressure to the fluid, the surgeon can inject the fluid between the tissue layers so that the location of the lesion to be treated can be dilated and marked. Injecting the fluid in this manner lifts and separates the tissue layers, facilitating both resection around the lesion and flattening through the submucosa, reducing the risk of perforation of the bowel wall and unnecessary thermal damage to the muscle layer.

[0140] The instrument tip 118 further includes a protective shell disposed under the active tip to assist in tissue-planing type cutting actions, also protecting against inadvertent perforation and helping to ensure viability of remaining tissue, which in turn promotes more rapid healing and post-operative recovery.

[0141] The structure of the instrument tip 118 may be specifically designed for use with conventional steerable flexible endoscopes having a working channel with an inner diameter of at least 2.2 mm and a working length between 60 cm and 170 cm. Thus, most relatively small diameter instruments are housed within the much larger, primarily polymeric isolator, lumen of the flexible endoscope channel. In practice, only 5 mm to 25 mm of the distal assembly protrudes beyond the distal end of the endoscope channel so as not to obstruct the field of view or adversely affect camera focusing. The protruding portion of the distal assembly is the only portion of the instrument that comes into direct contact with the patient.

[0142] At the proximal end of the working channel of the endoscope, which is typically held 50-80 cm away from the patient, the flexible shaft 112 exits the working channel port and extends a further 30-100 cm to the interface joint 106. In use, the interface joint 106 is typically held by a gloved assistant throughout the procedure. The interface cable 104 is connected to the generator 102 using a QMA type coaxial interface designed to allow continuous clockwise or counterclockwise rotation. This allows the interface joint 106 to rotate with the torque transfer unit 116 under the control of the user. The assistant supports the interface joint 106 throughout the procedure to assist the user in rotating instruments by resonance and injecting fluids.

[0143] FIG. 2 shows a graph useful for understanding embodiments of the present invention. The graph shows the electric field at various positions along the length l of a half-wave resonator. E and the variation of the current I over the length of the resonator. The current I over the length of the resonator approximately follows a half-sine wave, with a value of zero at the proximal end of the resonator, a peak at the center of the resonator, and a value of zero at the distal end of the resonator. E follows a corresponding cosine half-wave, with a peak value at the proximal end of the resonator, zero at the center of the resonator, and another peak at the distal end of the resonator. The half-wave shown in FIG. 2 reverses every half cycle.

[0144] In some embodiments, the inventors have developed an instrument tip configured as a half-wave resonator. Because inductance is related to current, and because the current peaks at the center of the resonator (as shown in FIG. 2), the inventors have found that for a half-wave resonator, the central zone of the instrument tip can be considered most critical to its inductance. Similarly, because capacitance is related to the electric field, and because the electric field peaks at the proximal and distal ends, the inventors have found that the proximal and distal zones of the conductive element can be considered most critical to the capacitance of the instrument tip.

[0145] Figures 3A, 3B and 3C show the dimensions of a prior art active tip 20 as described in GB2 523 246. The prior art active tip 20 has a planar body 22 including a dielectric substrate that separates a first conductive element 24 on a first surface from a second conductive element on a second surface. The prior art active tip has an overall length of 10.6 mm, a maximum width of 2 mm and a height of 0.5 mm. The first conductive element 24 on the prior art active tip 20 has a thickness of 0.03 mm.

[0146] The conductive layers on both sides of the planar body 22 are set back from the edge of the planar body 22 a distance of 0.2 mm along the proximal 6 mm of the tip 20. To ensure that the top conductive layer 24 is isolated from the outer conductor of the coaxial cable, the top conductive layer 24 is set back from the proximal edge of the dielectric substrate a distance of 0.6 mm.

[0147] Because the first conductive element 24 includes a proximal portion that is recessed from the edge of the planar body, the first conductive element 24 may be considered to be patterned relative to a reference conductive element that completely covers the first surface of an equivalent (reference) planar body. However, the recessed pattern of the prior art active tip 20 does not increase the electrical length of the prior art instrument tip compared to the electrical length of the reference instrument tip.

[0148] Instead, the recessed conductive regions do not substantially affect the electrical length.

[0149] The conductive element 24 includes patterned segments that recede in two zones at the tip of the instrument: a proximal zone that is generally capacitive in nature, and a central zone that is generally inductive in nature. The receding patterned segments can be considered to be half capacitive and half inductive.

[0150] In the proximal zone, recessing the conductive element 24 from the edge of the body has the effect of reducing the capacitance since the capacitance C is proportional to the overlapping area A of the conductive plates as follows:

number

[0151] In the central zone, narrower transmission lines have a higher inductance than wider transmission lines, so setting back the conductive elements 24 from the edges of the plane has the effect of increasing the inductance.

[0152] Because the conductive element 24 has the same width in the proximal and central zones, i.e., there is no relative difference in width between the conductive regions in these zones, the reduction in capacitance and the increase in inductance substantially cancel each other out, and as a result, the setback pattern does not substantially affect the resonant frequency or electrical length.

[0153] Thus, overall, the prior art recessed pattern does not affect the electrical length compared to a reference conductive element that covers the entirety of a (comparable) reference plane.

[0154] It is further noted that the first conductive element 24 includes a curved distal segment, however, because the curved distal segment already covers the (also curved) plane 22, the pattern results in no change in electrical length compared to a reference conductive element that also covers the entirety of a reference plane having the same shape and dimensions.

[0155] However, the curvature of the curved distal segment has the effect of modifying the electrical length compared to a rectangular reference conductive element resting on a rectangular reference plane. However, because it removes capacitance from the distal zone of the instrument, it also has the effect of decreasing (rather than increasing) the electrical length compared to the effect of a rectangular conductive element. This effect is also explained in GB2 503 673, which explains how a similar curved instrument tip needed to be physically longer to provide the required resonant characteristics to account for the reduction in capacitance caused by the curved distal tip.

[0156] Thus, in prior art configurations, the minimum physical length of the instrument tip was limited by the requirement to provide the necessary electrical length: the instrument tip could not be made smaller because any reduction in the size of the conductive element would in turn further reduce the capacitance C, thus undesirably further increasing the electrical length beyond that required for resonance.

[0157] In contrast, the inventors have developed an improved active tip that can be smaller than prior art active tips while providing a desired electrical length and maintaining the ability to efficiently transfer energy into biological tissue.

[0158] For example, some embodiments described herein provide improvements to the central, proximal, and / or distal zones of the active tip to aid in tuning its inductance and / or capacitance. In doing so, the inventors have provided an active tip that may be reduced in size compared to prior art active tips while maintaining functionality at a desired resonant frequency (e.g., 5.8 GHz) and maintaining an efficient impedance match with the target tissue.

[0159] 4 and 5 show an instrument tip 118 according to a first embodiment of the present invention. The instrument tip 118 includes an active tip 120 having a planar body 122 that separates a first conductive element 124 on a first surface of the planar body 122 from a second conductive element 126 on a second surface of the planar body 122. The instrument tip may further include a protective shell 128 under the active tip 120.

[0160] The coaxial cable 130 includes an inner conductor 132, an outer conductor 134 coaxial with the inner conductor 132, and a dielectric material 136 separating the inner and outer conductors. The inner conductor 132 is electrically connected to the first conductive element 124 and the outer conductor 134 is electrically connected to the second conductive element 126 to enable the active tip 120 to receive a working signal.

[0161] Body 122 includes four quadrants along its length, with the middle two quadrants forming a central zone 138 and the proximal and distal-most quadrants forming a proximal zone 140 and a distal zone 142, respectively.

[0162] First conductive element 124 has a pattern configured to set the electrical length of instrument tip 118 to be greater than the electrical length of reference instrument tip 144 (shown in FIG. 6 ). Reference instrument tip 144 is identical to instrument tip 118 (e.g., has the same shape and physical length) except for the fact that it includes reference conductive element 146 that completely covers a first surface of the planar body of reference instrument tip 144. Thus, reference instrument tip 144 does not function at the same operating frequency as instrument tip 118.

[0163] The plane 122 comprises a dielectric material, such as alumina, which has a dielectric constant of 9.8. Under these conditions, a half-wave resonator with a frequency of 5.8 GHz has

number

[0164] The first conductive element 124 has a proximal capacitive element 148 in the proximal zone 140 , a central inductive element 150 in the central zone 138 , and a distal capacitive element 152 in the distal zone 142 .

[0165] 2, the proximal and distal zones 140, 142 of the instrument tip can each be considered to define an area that primarily contributes to the capacitance (as opposed to the inductance) of the instrument tip 118. Conversely, the central zone 140 can be considered to define an area that primarily contributes to the inductance (as opposed to the capacitance) of the instrument tip 118.

[0166] 4 and 5, the proximal capacitive element 148 of the first conductive element 124 is formed as a generally rectangular capacitive plate. The capacitive plate is set back from the side edges of the planar body 122 by a pair of gaps 154. The gaps 154 may also serve to reduce the transfer of energy from the capacitive element 148 into the tissue, thereby helping to ensure that energy is transferred primarily from the distal zone 142 of the instrument tip 118.

[0167] The instrument tip further includes a chamfered spacer element 156 proximal to the planar body 122 , with the inner conductor 132 electrically connected to the first conductive element 124 by a proximal transmission line overlying the spacer element 156 .

[0168] The central inductive element 150 is configured as a straight (linear) thin track connecting the proximal capacitive element 148 to the distal capacitive element 152. In this embodiment, the central inductive element 150 includes a width that is less than 20% of the maximum width of the instrument tip 118, for example, about 10% of the maximum width of the instrument tip 118.

[0169] The distal capacitive element 152 is a continuous metallization layer that extends (i.e., without setbacks by gaps) to the edges of the planar body 122. Thus, the distal capacitive element 152 can maintain intimate contact with the tissue being treated (or diagnosed).

[0170] The pattern of the instrument tip 118 differs from the pattern of the reference instrument tip 144 in that the pattern of the instrument tip 118 removes conductive material from the proximal zone 140 (e.g., due to the gaps 154 around the proximal capacitive element 148) and removes conductive material from the central zone (due to the narrow central inductive element 150).

[0171] The setbacks in the proximal zone 140 have the effect of slightly reducing the electrical length of the instrument tip 118 compared to the electrical length of the reference instrument tip 144. This proximal capacitive section 148 may therefore be considered to provide an electrically shortening pattern. However, the central inductive element 150 is significantly narrowed, increasing its inductance and thereby providing an effect of increasing the electrical length to an extent that counteracts and outweighs the effect of any electrical shortening in the proximal zone 140. Thus, overall, the pattern provides a net effect of setting the electrical length of the instrument tip 118 to be greater than the electrical length of the reference instrument tip 144. For example, in this embodiment, the pattern provides an electrical length approaching 8.3 mm with a working signal having a frequency of 5.8 GHz. Thus, the instrument tip 118 is configured as a half-wave resonator for transmitting a working signal comprising a microwave signal at 5.8 GHz. Moreover, in this embodiment, the active tip 120 achieves this electrical length while having a relatively short physical length of 8.1 mm and a maximum length of 1.8 mm.

[0172] Thus, the instrument tip 118 can be physically smaller than that of the prior art, and in fact can even be physically smaller than the calculated electrical length.

[0173] In other dimensions, similar to the prior art active tip 20 of Figures 3A-3C, the active tip 120 may also have a height of 0.5 mm and the conductive element 124 may have a thickness of 0.03 mm.

[0174] In other words, the conductive element 124 is physically smaller than the conductive element 24 of the prior art active tip 20, so that the active tip 120 has a relatively lower capacitance than the prior art active tip 20. The conductive element 124 therefore has an improved pattern to provide a relatively higher inductance. This helps to counteract the effect of the reduced capacitance and provide an adequate electrical length. In this embodiment, the improvement includes a central inductive element 150 in the form of a narrow linear track that serves as a transmission line connecting the proximal and distal elements 148 and 152. By narrowing the conductive element 124 in the central zone 138, its inductance is increased, and therefore it can be made smaller than the prior art active tip 20 while maintaining the required electrical length.

[0175] FIG. 7 is a side-by-side comparison showing the size difference between the prior art active tip 20 and the improved active tip 120 of the first embodiment. FIG. 7 is drawn to scale and includes a grid spacing of 0.5 mm per square. As can be seen, the improved active tip 120 is significantly shorter than the prior art active tip 20.

[0176] Furthermore, Figures 8A-9B demonstrate that even this short active tip 120 can provide fairly efficient energy transfer into tissue. In particular, Figures 8A-8C and 9A-9B show the energy distribution of the active tip 120 inserted into liver tissue 158 at two different insertion positions.

[0177] Figure 8A shows the active tip 120 with the distal tip inserted into tissue 158. Figure 8B shows the power loss density around the distal capacitive element 152 when inserted into tissue 158 in the position shown in Figure 8A. As can be seen in Figure 8B, the active tip 120 provides a relatively symmetric and uniform spread of energy within the tissue 158.

[0178] 8C shows a graph of the scattering parameters ("S-parameters") provided by the active tip 120 in this position over a range of frequencies. This type of graph can effectively provide an understanding of the efficiency with which the active tip 120 transfers energy into tissue 158, according to the following approximate conversion table: [Table 1]

[0179] As can be seen from FIG. 8C, with a resonant frequency of 5.8 GHz and the distal tip fully inserted into tissue 158, the improved active tip 120 provides an S-parameter of −3.9 dB, resulting in an efficiency of approximately 60% when transferring energy into tissue.

[0180] As can be seen from Figures 9A and 9B, when the resonant frequency is 5.8 GHz and the distal tip is partially inserted into tissue 158 (only on the lateral side of the distal tip), the improved active tip 120 provides an S-parameter of -3.2 dB, thereby providing approximately 50% efficiency in transferring energy into tissue.

[0181] Thus, the first embodiment is useful for providing a relatively consistent energy transfer efficiency even as the impedance at the distal tip changes (i.e., when changing the amount of tissue in contact with the device.) Additionally, the first embodiment provides a uniform distribution of energy around the periphery of the device (as can be seen in FIG. 8B) while providing a relatively small physical configuration for a desired electrical length.

[0182] Figures 10 and 11 show an active tip 220 according to a second embodiment of the present invention. The active tip 220 is generally similar to the active tip 120 of the first embodiment, and like reference numbers refer to like elements unless otherwise noted. For example, as shown in Figure 10, the second embodiment may have the same dimensions as the first embodiment. Figure 10 is drawn to scale and includes a grid spacing of 0.5 mm per square.

[0183] Compared to the first embodiment, the active tip 220 of the second embodiment can help to further improve the efficiency of energy transfer by varying the capacitance and inductance of the first conductive element to improve impedance matching with the coaxial cable.

[0184] In particular, the active tip 220 differs from the active tip 120 in that the active tip 220 has a distal element that is hollowed out to form a loop 260 around a non-conductive void 262. The loop 260 may therefore be considered to provide both a capacitive effect (at the distal zone 242 of the active tip) and an inductive effect (at the central zone 238 of the active tip 220). In particular, the hollow loop 260 reduces the capacitance of the active tip 220 compared to the active tip 120. Furthermore, this effectively provides an extended central inductive element 264, e.g., further including a pair of arms 266 that project laterally into the central zone 238 of the active tip 220, thereby increasing the inductance of the active tip 220. The impedance may be expressed as:

number

[0185] The curved portion of the conductive loop 260 extends along the curved periphery of the planar body 122 in the distal zone 242 to form a cutting edge for contacting tissue. The loop 260 along the curved periphery of the planar body 122 can serve as a convenient indicator for the clinician to more easily visualize the cutting surface of the active tip 220.

[0186] Advantageously, the active tip 220 can help provide uniform energy distribution and improve efficiency of energy delivery even with varying positions of the active tip 220 relative to the tissue. For example, Figures 12A-14C show the efficiency and energy distribution of the active tip 220 at three different positions relative to liver tissue 158.

[0187] Figure 12A shows the active tip 220 in a first position where only the distal-most portion of the active tip 220 is inserted into the tissue 158. As shown in Figure 12B, this provides a relatively uniform energy distribution around the active tip. As shown in Figure 12C, the resulting S-parameter at 5.8 GHz is -4.1 dB, indicating that the active tip 220 at this frequency and position is approximately 60% efficient.

[0188] Figure 13A shows the active tip 220 in a second position that is further inserted into tissue at an even greater depth than the first position. As shown in Figure 13B, this also provides a relatively even distribution of energy around the active tip 220. Furthermore, as shown in Figure 13C, the resulting S-parameter at 5.8 GHz is -4.5 dB, indicating that the active tip 220 at this frequency and position is approximately 65% ​​efficient.

[0189] Figure 14A shows the active tip 220 in a third position. In this position, the active tip 220 is inserted into the tissue 158 at the same depth as in the second position, but only along one lateral side of the active tip 220. As shown in Figure 14B, this also provides a relatively uniform distribution of energy around the active tip. Furthermore, as shown in Figure 14C, the resulting S-parameter at 5.8 GHz is -4.1 dB, indicating that the active tip 220 at this frequency and position is approximately 60% efficient.

[0190] Thus, the active tip 220 is useful for improving the efficiency of energy transfer as compared to the active tip 220, and for improving the consistency of that efficiency even as the impedance at the active tip 220 changes (i.e., changing the amount of tissue in contact with the device).

[0191] 15 and 16 show an active tip 320 according to a third embodiment of the present invention.

[0192] The figures showing active tip 320 include similar reference numbers to the figures showing active tips 120 and 220 to indicate similar elements, unless otherwise noted. Active tip 320 has the same dimensions as active tips 120 and 220. Figure 15 is drawn to scale and includes a grid spacing of 0.5 mm per square.

[0193] Active tip 320 differs from active tips 120 and 220 in that it has a narrowed proximal section that further reduces the capacitance of the conductive track (which in turn reduces the electrical length). To compensate for this and electrically extend active tip 320 to the required length, active tip 320 includes a pair of extension sections 368 configured to increase the physical length of conductive element 324 compared to the physical length of planar body 122.

[0194] More specifically, at the proximal zone 340 of the active tip 320, the first conductive element 324 includes a capacitive element 348 that includes a plate (or "bulb") that is significantly narrower than the planar body 122 (e.g., about 1 / 3 the width of the proximal zone 340 of the planar body 122). The conductive element 122 further includes a conductive track 370 that extends longitudinally from the capacitive element 348 through the distal-most section of the central zone 342. At approximately the center of the planar body 122 (i.e., where the body begins to bend inward), the conductive track 370 branches into a pair of tracks 372A and 372B that are spaced apart from each other and extend to the distal tip of the planar body 122. At the distal tip, the tracks 372A and 372B then extend outward along their respective peripheries of the planar body 122 to form a pair of branches 374A and 374B that project rearward toward the proximal region of the planar body 122. In this embodiment, each branch 374A and 374B terminates in a respective terminus disposed at a respective periphery of the central zone 338 of the active tip 320. In this configuration, the effective center of capacitance at the distal end is approximately halfway along the branches 374A and 374B at the periphery of the planar body 122.

[0195] Branches 374A and 374B effectively serve to increase the physical length of conductive element 324, which in turn increases its electrical length as seen by a working signal transmitted along active tip 320. Because branches 374A and 374B extend along the periphery of planar body 122, branches 374A and 374B may also be used to perform a working (therapeutic or diagnostic) function and provide an easily visualized working surface for a clinician manipulating the instrument.

[0196] 17A-19B show the efficiency and energy distribution of the active tip 320 at three different positions relative to liver tissue 158. FIG.

[0197] Figure 17A shows the active tip 320 in a first position where only the distal-most portion of the active tip 320 is inserted into the tissue 158. As shown in Figure 17B, this provides a relatively uniform energy distribution around the active tip. As shown in Figure 17C, the resulting S-parameter at 5.8 GHz is -2.05 dB, indicating that the active tip 320 at this frequency and position is approximately 37% efficient.

[0198] Figure 18A shows the active tip 320 in a second position that is further inserted into the tissue 158 at an even greater depth than the first position. As shown in Figure 18B, this also provides a relatively even distribution of energy around the active tip 320. Furthermore, as shown in Figure 18C, the resulting S-parameter at 5.8 GHz is -6.5 dB, indicating that the active tip 320 at this frequency and position is approximately 78% efficient.

[0199] Figure 19A shows the active tip 320 in a third position, where the active tip 320 is inserted into tissue 158 at the same depth as in the second position, but only along one lateral side of the active tip 320. As shown in Figure 19B, this results in a resulting S-parameter of -1.9 dB at 5.8 GHz, indicating that the active tip at this frequency and position is approximately 35% efficient.

[0200] FIG. 20 shows another instrument tip 418 that includes an active tip 420 having a first conductive element 424 intended to increase its physical length compared to the physical length of the planar body.

[0201] At a distal portion of the active tip 420 (eg, the distal 40% of the active tip), the conductive element 424 extends across the entire planar body to form a distal capacitive element (capacitive plate) 452 .

[0202] At a proximal portion of the active tip (e.g., the proximal 60% of the active tip), the conductive element 424 is patterned as an elongated track having multiple deflections 476 along its length to form a square wave shape 478 extending between the coaxial cable 130 and the distal capacitive element 452.

[0203] The square wave tracks were designed to increase the physical length of the conductive element compared to the physical length of the plane body and then increase the electrical length of the conductive element compared to a reference conductive element that extends across the entire surface of the plane body.

[0204] However, if adjacent sections of the square wave track are very close to each other, the working signal (e.g., microwave frequency energy at 5.8 GHz) can couple across the square wave in use, effectively bypassing the square wave portion and traveling directly to the distal end (e.g., along a path approximately aligned with the longitudinal axis of the instrument tip).

[0205] Thus, according to this embodiment, the pattern is selected to create gaps between adjacent conductive sections of a size (e.g., 1 mm from each other for a planar body having a thickness of 0.5 mm) that prevents the working signal from coupling across the gap. This configuration provides an extended section that is configured to transmit the working signal around the extended portion of the track, thereby increasing its electrical length.

[0206] Figure 26 illustrates an electrosurgical instrument tip 718 having an active tip 720 according to another embodiment of the present invention. Figure 26 includes similar reference numbers to those described above to indicate similar elements, unless otherwise noted.

[0207] 10 and 11, but has a different pattern that allows the instrument tip 718 to be made smaller while still providing adequate electrical length and impedance matching. In particular, the instrument tip 718 has a pattern that does not include a central, longitudinally extending portion of the inductive element 264. Instead, the instrument tip 718 has a conductive loop 760 that connects directly to the distal end of the conductive (capacitive) plate 748 and has a conductive loop 760 around a non-conductive void 762 that provides the desired inductance.

[0208] More specifically, as shown in Figure 26, active tip 718 may be significantly shorter than active tip 218. In this embodiment, active tip 718 has a physical length of 6.56 mm and is configured to operate as a half-wave resonator at a working frequency of 5.8 GHz.

[0209] In comparison to the above-described embodiments, the active tip 718 is shorter at the proximal (rectangular) portion of the planar body 722. That is, the active tip 718 may have a distal portion (e.g., a curved portion) having the same length as the curved distal portion of FIG. 10 and thus may provide a similar interaction with tissue, e.g., by providing a similarly sized cutting surface.

[0210] The active tip 718 includes a proximal zone 740 in the proximal quadrant of the planar body 722 , a central zone 738 in the central two quadrants of the planar body 722 , and a distal zone 742 in the distal quadrant of the planar body 722 .

[0211] The active tip 718 includes a conductive element 724 that is patterned in a proximal zone 740 to include a rectangular capacitive element 748. The capacitive element 748 is generally similar to the capacitive elements 148 and 248 described with respect to Figures 4 and 10.

[0212] At the distal end of the capacitive element 748 (within the central zone 738), the capacitive element 748 is directly connected to a conductive loop 760. The portion of the conductive loop within the central zone 738 may be considered to function as a pair of inductive elements extending longitudinally around opposing peripheries of the central zone 738 of the planar body 722 toward the distal end of the active tip 720. This configuration may increase the inductance at the central zone 738 compared to the pattern shown in Figure 10, thereby allowing the size of the instrument tip to be further reduced while maintaining the desired electrical performance.

[0213] For example, Figure 27 shows the S-parameters of the active tip 720 inserted into liver tissue 158. As shown in Figure 26, the active tip 720 exhibits an S-parameter of -7.4, indicating an efficiency of about 82% at this frequency. The active tip 720 was also found to have high efficiency and uniform energy distribution as it changes position relative to the liver 158.

[0214] Figures 21-23E show an electrosurgical instrument tip 518 having an active tip 520 according to a second embodiment of the present invention. Figures 21-23E include similar reference numbers as described above to indicate similar elements unless otherwise noted. Figure 21 is drawn to scale and includes a grid spacing of 0.5 mm per square. The active tip 520 may have the same dimensions as the active tips 120, 220, 320, and 420.

[0215] Active tip 520 may provide even further improved efficiency of energy transfer compared to active tips 120, 220, 320, and 420 and / or compared to active tips described in the prior art.

[0216] In contrast to the previous active tips (each of which was configured as a half-wave resonator), active tip 520 is not configured as a resonator. Instead, active tip 520 is configured as a lossy transmission line.

[0217] The active tip 520 includes an elongated track 580 that extends from a proximal region 582 of the planar body 122 around the periphery of a distal region 584 of the planar body 122 for contacting tissue.

[0218] At a proximal region (e.g., proximal half) 582 of the active tip 520, the elongated track 580 includes an enlarged proximal end 586 for connection to the coaxial cable 130. The elongated track 580 further includes a narrower thin track having a straight (linear) portion 588 extending longitudinally along a central axis of the planar body, for example. The size of the proximal end 586 and / or straight portion 588 can be selectively configured to provide impedance matching with the coaxial cable 130 and / or tissue. For example, the enlarged proximal end 586 can have a width of about 35% of the width of the proximal region 582 of the planar body 122, and the straight portion 588 can have a narrower width of about 25% of the width of the proximal region 582 of the planar body 122. In alternative embodiments, the thin track may not be straight, for example, the thin track may have a wavy or other non-linear shape.

[0219] At the end of the straight portion 588, the elongated track 580 includes a first deflection 590A (bend, corner) that turns and extends transversely to the longitudinal axis of the planar body, i.e., toward the periphery of the distal region 584 (e.g., distal half) of the active tip 520. The elongated track 580 then further includes a second deflection 590B (bend, corner) that turns and extends around the periphery of the distal region 584. The section of the elongated track 580 that extends around the periphery (along the edge) of the distal region 584 of the planar body 122 may be referred to as the peripheral section 592.

[0220] The peripheral section 592 terminates at a third deflected portion 590C (corner) of the planar body 122 opposite the second deflected portion 590B.

[0221] After the third deflection portion 590C, the elongated track 580 includes an extension section 594 that includes a fourth deflection portion 590D (corner) that turns into a linear track (branching portion) that extends longitudinally toward the distal end of the active tip 520. Thus, the peripheral section 592 and the extension section 594 together form a spiral at the distal region 584 of the active tip 520, with the peripheral section 592 defining an outer portion of the spiral and the extension section 594 defining an inner portion of the spiral.

[0222] The peripheral section 592 and the extension section 594 form adjacent portions of a spiral separated along its length by a U-shaped gap 596. The gap 596, the peripheral section 592, and the extension section 594 each have a width that is approximately 20% of the maximum width of the distal region (although their widths may vary, e.g., taper slightly toward the narrower distal end of the active tip 520). The relatively large gap 596 may help prevent the working signal from coupling between adjacent sections of the spiral.

[0223] During use, the active tip 520 can be in contact with tissue, which acts as a load at the distal end of the active tip 520. The active tip 520 can transmit a working signal along the straight portion 588 and around the peripheral section 592. Because the peripheral section 592 is relatively narrow (e.g., less than 0.5 mm wide), the peripheral section 592 can provide a relatively high energy distribution across its width while being in intimate contact with the tissue. Additionally, because the peripheral section 592 is relatively long (e.g., extending around the distal 40% of the planar body), the peripheral section 592 can transmit this energy into the tissue along a longer track length (e.g., compared to a conductive element covering the entire planar body). Thus, the working signal can be efficiently transmitted into the tissue and then reduced in amplitude significantly along the elongated track 580 to provide a significantly reduced amplitude at the terminal end 598 of the elongated track 580.

[0224] 22A-23 show the efficiency and energy distribution of the active tip 520 at two different positions relative to the liver tissue 158. FIG.

[0225] 22A-22B show the active tip 520 with the majority of the peripheral section 592 inserted into tissue. As shown in FIG. 22B, this causes a greater amount of energy to be provided into the tissue near the input end of the peripheral section 592 (i.e., electrically closer to the coaxial cable 130) than near the output end of the peripheral section 592 (i.e., electrically closer to the extension section 594).

[0226] Similarly, Figures 23A-23E show the energy distribution at various positions as the active tip 520 is inserted into tissue 158. As shown in these figures, the power density is greatest near the input end of the peripheral section 592 and tapers off around the entire length of the peripheral section 592. The power density also tapers off when tissue (the load) is on only one lateral side of the active tip, as shown in Figure 23D. In alternative embodiments, the width of the peripheral track and / or its proximity to the edge of the planar body may be modified to provide more uniform power absorption.

[0227] Thus, the above-described active tips 120, 220, 320, and 420 may provide an even more uniform energy distribution than the active tip 520, since the energy distribution is symmetric on both lateral sides of the active tips 120, 220, 320, and 420. However, the active tip 520 may provide a configuration that can transfer energy into tissue more efficiently. For example, as shown in FIG. 22C, the resulting S-parameter at 5.8 GHz and the location of FIG. 22A and FIG. 22B is −7.8 dB, indicating that the active tip 520 at this frequency and location is approximately 83% efficient.

[0228] 24A-25B show an electrosurgical instrument tip 618 having an active tip 620 according to another embodiment of the second aspect of the present invention.

[0229] Active tip 620 is similar to active tip 520, but does not include an enlarged proximal end for a linear track in the proximal region. Instead, conductive element 624 has a linear track 688 that extends to the proximal end and has a constant width along its entire length.

[0230] Figure 24B shows the S-parameters for this active tip 620 in the position of Figure 24A (liver tissue 158 covering only the tip of the peripheral section 620), providing an S-parameter of -7.7 indicating an 83% efficiency of the active tip 620 at this frequency and position. Figure 25B shows the S-parameters for the active tip 620 in the position of Figure 25B (liver tissue covering the entire peripheral section 592), providing an S-parameter of -10.8 indicating an 92% efficiency of the active tip 620 at this frequency and position.

[0231] The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, and presented in a particular form or in terms of means for performing a disclosed function, or a method or process for achieving a disclosed result, may be used separately or in any combination of such features, as appropriate, to realize the invention in its diverse forms.

[0232] Although the present invention has been described in conjunction with the above exemplary embodiments, many equivalent modifications and variations will be apparent to those skilled in the art given this disclosure. Accordingly, the above exemplary embodiments of the present invention are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the present invention.

[0233] For the avoidance of doubt, the theoretical explanations provided herein are provided for the purpose of enhancing the understanding of the reader, and the inventors do not wish to be bound by any of these theoretical explanations.

[0234] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0235] Throughout this specification, including the claims which follow, unless the context specifically requires, the words "comprise" and "include", and variations such as "comprises", "comprising" and "including", are understood to imply the inclusion of a stated integer value or step, or group of integer values ​​or steps, but not the exclusion of other integer values ​​or steps, or group of integer values ​​or steps.

[0236] It should be noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from "about" one particular value and / or to "about" another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values ​​are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another embodiment. The term "about" in connection with numerical values ​​is arbitrary and may mean, for example, + / - 10%.

[0237] 100 Electrosurgical System 102 Generator 104 Interface cable 106 Interface Joint 112 Flexible shaft 118 Electrosurgical Instrument Tip 107 Fluid supply cable 114 Surgical Scoping Device 116 Torque transmission unit 108 Fluid Delivery Device 20 Active Leading Edge of Prior Art 22 Planar body 24 First conductive element 118 Instrument tip 120 Active Tip 138 Central Zone 140 Proximal Zone 142 Distal Zone 122 Planar body 124 First conductive element 148 Proximal Capacitive Element 150 Central inductive element 152 Distal Capacitive Element 126 Second conductive element 154 Gap 156 Spacer Element 128 Protective Shell 130 Coaxial power supply cable 132 Inner conductor 134 Outer conductor 136 Dielectrics 144 Reference Instrument Tip 146 Reference first conductive element 158 tissue samples 218 Instrument tip 220 Active Tip 260 Loops 262 Non-conductive voids 264 Central Inductive Element 266 Arm 318 Instrument tip 320 Active Tip 368 Electrically extended section 370 Capacitive Truck 372A, B track pair 374A, B branch pair 418 Instrument tip 420 Active Tip 476 Deflection section 478 square wave 518 Instrument tip 520 Active Tip 580 Narrow Truck 582 Proximal Region 584 Distal Region 586 Enlarged Proximal End 588 Narrow Straight Section 590A, B, C, D deflection section 592 Peripheral Section 594 Extension Section 596 Gap 598 End 618 Instrument tip 620 Active Tip 688 Straight Track 718 Instrument tip 720 Active Tip 722 Planar body 724 Conductive elements 738 Central Zone 740 Proximal Zone 742 Distal Zone 748 Conductive Plate 760 Conductive Loop 762 Non-conductive void

Claims

1. 1. An electrosurgical instrument for applying radio frequency (RF) electromagnetic (EM) energy and / or microwave frequency EM energy to living tissue, comprising: an instrument tip comprising a planar body separating a first conductive element on a first surface from a second conductive element on a second surface, the second surface facing away from the first surface; a coaxial feeder cable comprising an inner conductor, an outer conductor coaxial with the inner conductor, and a dielectric separating the inner and outer conductors, the coaxial feeder cable being for transmitting a working signal comprising an RF signal and / or a microwave signal; Equipped with the inner conductor is electrically connected to the first conductive element and the outer conductor is electrically connected to the second conductive element to enable the instrument tip to receive the working signal; the first conductive element includes a pattern configured to set the electrical length of the instrument tip to be greater than the electrical length of a reference instrument tip; the reference instrument tip comprises a reference plane separating a reference first conductive element completely covering a reference first surface from a reference second conductive element completely covering a reference second surface, the reference instrument tip being otherwise identical to the electrosurgical instrument, the reference second surface facing away from the reference first surface, and the reference plane having the same shape and dimensions as the plane. The electrosurgical instrument.

2. 10. The electrosurgical instrument of claim 1, wherein the instrument tip is configured as a half-wave resonator, and optionally the instrument tip is configured to resonate at one of the following predetermined frequencies: 915 MHz, 2.45 GHz, 5.8 GHz, 14.5 GHz, 24 GHz.

3. 3. An electrosurgical instrument according to claim 1 or 2, wherein the instrument tip comprises four quadrants along its length, the central two quadrants being joined together to form a central zone, and the pattern forming at least one inductive element in the central zone.

4. 4. The electrosurgical instrument of claim 3, wherein the inductive element includes a first conductive region having a width that is 90% or less of a maximum width of a second conductive region of the first conductive element, the second conductive region being disposed in a distal zone or a proximal zone.

5. The electrosurgical instrument of claim 1 , wherein the pattern includes an extension section configured to increase the physical length of the first conductive element relative to the physical length of the planar body.

6. The electrosurgical instrument of claim 5 , wherein the extension section has a wavy shape.

7. 7. An electrosurgical instrument according to claim 5 or 6, wherein the extension section includes one or more branches extending along one or more peripheral edges of each of the planar bodies.

8. The electrosurgical instrument of claim 1 , wherein the pattern forms at least one capacitive element in a distal or proximal quadrant of the instrument tip.

9. 9. An electrosurgical instrument according to claim 8, wherein the or each capacitive element includes a conductive region having an area that fills most or all of the distal or proximal quadrant in which it is formed.

10. The electrosurgical instrument of claim 1 , wherein the pattern includes conductive loops surrounding non-conductive areas.

11. The electrosurgical instrument of claim 10 , wherein the conductive loop is configured to extend along one or more edges of the planar body in a distal zone of the instrument tip.

12. The electrosurgical instrument of claim 1 , wherein the pattern is symmetrical about a longitudinal axis of the instrument tip.

13. The electrosurgical instrument of claim 1 , wherein the second conductive element covers most or all of the second surface of the planar body.

14. 2. The electrosurgical instrument of claim 1, wherein the instrument tip includes a spacer element proximal to the planar body, the inner conductor being electrically connected to the first conductive element by a proximal transmission line on the spacer element, and the spacer element being chamfered.

15. The electrosurgical instrument of claim 1 , wherein the distal end of the planar body is curved.

16. The electrosurgical instrument of claim 1 , wherein the pattern configures the electrical length of the instrument tip to be equal to or greater than the physical length of the instrument tip.

17. The electrosurgical instrument of claim 1 , wherein the planar body comprises a ferrite material.

18. 1. An electrosurgical instrument for applying radio frequency (RF) electromagnetic (EM) energy and / or microwave frequency EM energy to living tissue, comprising: an instrument tip comprising a planar body separating a first conductive element on a first surface from a second conductive element on a second surface, the second surface facing away from the first surface; a coaxial feeder cable comprising an inner conductor, an outer conductor coaxial with the inner conductor, and a dielectric separating the inner and outer conductors, the coaxial feeder cable being for transmitting a working signal comprising an RF signal and / or a microwave signal; Equipped with the inner conductor is electrically connected to the first conductive element and the outer conductor is electrically connected to the second conductive element to enable the instrument tip to receive the working signal; the first conductive element comprises an elongated track having a peripheral section for transmitting the working signal around a periphery of a distal region of the instrument tip for contacting tissue; The electrosurgical instrument.

19. The electrosurgical instrument of claim 18, wherein the peripheral section has a width less than 30%, optionally less than 20%, optionally less than 10% of the maximum width of the distal region.

20. 20. The electrosurgical instrument of claim 18 or 19, wherein the peripheral section extends around at least a distal 30% of the planar body, optionally at least a distal 40% of the planar body, optionally at least a distal 50% of the planar body.

21. 20. The electrosurgical instrument of claim 18, wherein the elongate track includes a proximal section for connecting the coaxial feed cable to the peripheral section, the proximal section being set back from one or more side edges of the planar body in a proximal region of the planar body.

22. 20. The electrosurgical instrument of claim 18, wherein the elongated track further includes an extension section with one or more deflections to further increase the physical length of the elongated track relative to the physical length of the planar body.

23. The electrosurgical instrument of claim 22 , wherein the extension section is disposed at the distal region of the instrument tip.

24. 24. The electrosurgical instrument of claim 23, wherein the peripheral section and the extension section together form a helix in the distal region of the instrument tip.

25. The electrosurgical instrument of claim 18, wherein the first conductive element is configured to match the impedance of the coaxial feed cable.

26. 1. An electrosurgical instrument for applying radio frequency (RF) electromagnetic (EM) energy and / or microwave frequency EM energy to living tissue, comprising: an instrument tip comprising a planar body separating a first conductive element on a first surface from a second conductive element on a second surface, the second surface facing away from the first surface; a coaxial feeder cable comprising an inner conductor, an outer conductor coaxial with the inner conductor, and a dielectric separating the inner and outer conductors, the coaxial feeder cable being for transmitting a working signal comprising an RF signal and / or a microwave signal; Equipped with the inner conductor is electrically connected to the first conductive element and the outer conductor is electrically connected to the second conductive element to enable the instrument tip to receive the working signal; the instrument tip further includes a spacer element proximal to the planar body, the spacer element being chamfered; The electrosurgical instrument.

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