Electrosurgical instrument

Abstract

Various embodiments provide an electrosurgical instrument comprising: a coaxial feed cable having an inner conductor, an outer conductor, and a dielectric material separating the inner conductor from the outer conductor, the coaxial feed cable being used to transmit microwave signals. The instrument further includes a radiating tip disposed at a distal end of the coaxial feed cable to receive the microwave signals. The radiating tip includes: an elongated element electrically connected to the inner conductor and extending in a longitudinal direction; and a loop element electrically connected to the elongated element, wherein the loop element is wound around at least a portion of the elongated element. Some other embodiments provide an electrosurgical device including the instrument.

Description

Technical Field

[0001] This invention relates to an electrosurgical device for delivering microwave energy to biological tissue to ablate it. The device may include a probe that can be inserted through a channel via an endoscope or catheter, or may be used in laparoscopic or open surgery. The device may be used for pulmonary or gastrointestinal applications, but is not limited thereto. Background Technology

[0002] Electromagnetic (EM) energy, and especially microwave energy, has been found to be useful in electrosurgery due to its ability to ablate biological tissue. Typically, devices for delivering EM energy to body tissues include a generator containing an EM energy source and electrosurgical instruments connected to the generator for delivering the energy to the tissue.

[0003] Conventional electrosurgical instruments are often designed for percutaneous insertion into the patient. However, percutaneous positioning of the instrument can be challenging, for example, if the target site is in a thin-walled segment of the moving lungs or gastrointestinal (GI) tract. Other electrosurgical instruments can be delivered to the target site via surgical endoscopic devices (such as endoscopes) that can operate through channels within the body, such as the airway or the lumen of the esophagus or colon. This allows for minimally invasive treatment, which can reduce patient mortality and intraoperative and postoperative complication rates.

[0004] Tissue ablation using microwave (EM) energy is based on the fact that biological tissues are primarily composed of water. The water content of human soft tissues is typically between 70% and 80%. Water molecules possess permanent electric dipole moments, meaning there is a charge imbalance throughout the molecule. This charge imbalance causes molecules to rotate in response to forces generated by an applied time-varying electric field, aligning their electric dipole moments with the polarity of the applied field. At microwave frequencies, rapid molecular vibrations lead to frictional heating, and the resulting field energy is dissipated as heat. This is known as dielectric heating.

[0005] This principle is utilized in microwave ablation therapy, where water molecules in the target tissue are rapidly heated by a localized electromagnetic field applied at microwave frequencies, leading to tissue coagulation and cell death. Microwave-emitting probes are known to be used to treat various diseases of the lungs and other organs. For example, in the lungs, microwave radiation can be used to treat asthma and ablate tumors or lesions. Summary of the Invention

[0006] It is generally desirable to reduce the size of electrosurgical instruments, for example, by making them thinner and / or shorter. Compact arrangement offers several advantages. For example, a compact arrangement allows instruments to be used within narrower viewing devices and / or smaller biological structures, makes instruments easier to manipulate, and / or can help improve control and precision at the instrument tip.

[0007] However, reducing the size of the device while maintaining its functionality is challenging. Specifically, to efficiently deliver energy to tissue, the device tip can be configured with a physical length corresponding to a specific electrical length (i.e., a certain number of wavelengths) at the desired energy frequency. For example, to provide efficient energy delivery at 5.8 GHz microwave energies, the physical length of the device tip can be selected to correspond to half a wavelength at that frequency (considering the dielectric constant of the material), allowing the device tip to act as a half-wavelength resonator. However, because the physical length of the device tip is selected to provide a specific electrical length (i.e., corresponding to a certain number of wavelengths at the desired frequency), the physical length of the device tip cannot be reduced while maintaining the desired electrical properties. Instead, when the physical length is reduced, the electrical length also decreases, resulting in destructive reflections at the interface with biological tissue at the desired frequency (e.g., 5.8 GHz) and reduced energy delivery efficiency through the device tip. Therefore, the ability to reduce the size of the device tip was previously limited by the need for efficient energy delivery. Furthermore, it should be noted that lower microwave frequencies require longer electrical lengths to effectively deliver energy to tissue due to the longer wavelengths.

[0008] According to a first aspect of the invention, an electrosurgical instrument is provided, comprising: a coaxial feed cable having an inner conductor, an outer conductor, and a dielectric material separating the inner and outer conductors, the coaxial feed cable being used to transmit microwave signals; and a radiating tip disposed (e.g., mounted) at a distal end of the coaxial feed cable to receive the microwave signals, wherein the radiating tip includes: an elongated element electrically connected (directly or indirectly) to the inner conductor and extending in a longitudinal direction; and a loop element wound (e.g., directly wound) around at least a portion of the elongated element. It should be understood that the elongated element and the loop element are insulated from each other, except for one or more electrical connection points or contacts. For example, one or both of the elongated element and the loop element may include an insulating layer (such as enamel, varnish, etc.), or the radiating tip may include an additional insulating layer that allows the elongated element and the loop element to approach each other (e.g., in physical contact) without creating undesirable electrical connections. The thickness of the insulating layer or additional insulating layer may be less than the thickness / diameter of the elongated element and / or the ring element, so as to provide the necessary insulation without significantly increasing the thickness / diameter of the radiating tip. For example, the maximum thickness / diameter of the radiating tip may be less than the maximum thickness / diameter of the coaxial feed cable. For example, when providing an insulating layer on or around the elongated element, the thickness of the insulating layer may be less than the thickness of the dielectric material of the coaxial feed cable (e.g., at least an order of magnitude smaller). For example, when providing an insulating layer on or around a conductive element wound to form a ring element, the thickness of the insulating layer may be less than the thickness of the dielectric material of the coaxial feed cable (e.g., at least an order of magnitude smaller). For example, when providing an additional insulating layer, the thickness of the additional insulating layer may be less than the thickness of the dielectric material of the coaxial feed cable (e.g., at least an order of magnitude smaller). It should be understood that the ring element (with or without an insulating layer) may be wound "directly" on the elongated element (with or without an insulating layer), meaning that there is no intermediate element, such as no intermediate dielectric, between the ring element and the elongated element. The insulating layer may be arranged to maintain the desired electrical length of the radiating portion. By winding around at least a portion of an elongated element, at least a portion of the annular element can make physical contact with that portion (and this may differ from an electrical contact point). The elongated element and the annular element can be collectively referred to as conductive elements, or as multiple conductive elements. In this document, the terms "elongated element" and "elongated conductor," as well as "annular element" and "annular conductor," are used interchangeably. The annular element can be a wound element, such as a helical element, and can include at least one loop surrounding the elongated element. In embodiments of the invention, when the annular element comprises multiple loops, turns, or coils, each loop can have different dimensions (e.g., radius, length), and the spacing between each loop can be uniform or varied.The inventors have discovered that the electrosurgical instrument according to the first aspect of the invention increases the effective electrical length of the radiating element, thereby reducing the physical size of the electrosurgical instrument while maintaining effectiveness at low microwave frequencies, and the instrument can also be used to deliver energy to tissues at a variety of microwave frequencies. As described herein, the effective frequency of the instrument can be tuned by changing the size of the radiating element.

[0009] It should be understood that the radiating tip is arranged to act as a microwave monopole antenna, which radiates microwave energy when a microwave signal is delivered to the tip in order to perform tissue treatment.

[0010] Therefore, the implementation can allow the physical size (e.g., length, diameter) of the device, particularly the radiating tip, to be smaller than that of the prior art arrangement, while maintaining the ability to efficiently deliver the same working signal (e.g., microwave frequency signal) into the tissue, because providing a ring-shaped element on the elongated element can increase the electrical length of the device, and thereby offset any reduction in electrical length that would occur when the physical size of the device is reduced.

[0011] As used herein, the phrase "electrical length" can refer to the length of the instrument tip calculated using the wavelength λ of the operating signal; that is, the length can refer to the length of the instrument tip as "seen" by the operating signal. Electrical length can be calculated as a fraction or multiple of the wavelength. For example, to act as a half-wave resonator, the instrument tip may have approximately... The electrical length. This can be calculated as where c is the speed of light and ε eff ε is the effective dielectric constant of the planar element. The effective dielectric constant can depend on the size of the conductive element and the material surrounding it. The effective dielectric constant can vary along the length of the conductive element (i.e., along the length of the radiating tip), and is therefore ε in the formula. eff Using a value can be an approximation.

[0012] Optionally, the elongated element may include a distal portion of the inner conductor extending beyond the distal end of the outer conductor.

[0013] Optionally, the ring element may include insulated wire, such as enameled wire (e.g., copper wire or other metal wire, including insulating varnish, etc.). For example, the insulation layer may be arranged to insulate a portion of the ring element (e.g., a middle section or a length) from the elongated element, which may be particularly advantageous in embodiments where the ring element is in physical contact with the elongated element (e.g., wrapped around the elongated element). In embodiments, the insulation layer surrounds all portions of the ring element except for the ends or end faces, or one or more surfaces of the ring element that are in electrical contact with the elongated element.

[0014] Optionally, the outer diameter of the radiating tip can be less than 5 mm, for example less than 2 mm. As explained above, the present invention is able to provide sufficient electrical length to operate at one or more microwave frequencies while having a narrow diameter, which is not possible with prior art arrangements.

[0015] Optionally, the ring element is also electrically connected to the outer conductor of the coaxial feed cable.

[0016] Optionally, the annular element may be spaced apart from the distal end of the outer conductor by a first distance. For example, the first distance may be between 1 mm and 5 mm, although in some embodiments the first distance may be 0 mm (i.e., the annular element may be positioned adjacent to the outer conductor, for example, electrically connected to the outer conductor). Adjusting the first distance may allow the radiating tip to be tuned to operate at a predetermined or desired microwave frequency.

[0017] Optionally, the annular element may be spaced apart from the distal end of the elongated element by a second distance. For example, the second distance may be between 1 mm and 5 mm, although in some embodiments, the second distance may be 0 mm (i.e., the annular element may be positioned adjacent to the distal end of the elongated element, for example, electrically connected to the distal end of the elongated element). Adjusting the second distance may allow the radiating tip to be tuned to operate at a predetermined or desired microwave frequency.

[0018] Optionally, the annular element may have at least five coils (e.g., at least five turns, loops, or windings). Adjusting the number of coils allows the radiating tip to be tuned to operate at a predetermined or desired microwave frequency. For example, the annular element may have 20 or more coils. However, it should be understood that some embodiments of the invention may include fewer coils, such as 2, 3, or 4 coils.

[0019] Optionally, the annular element can be tightly wound around an elongated element such that adjacent coils of the annular element are in contact with each other. This may help increase the electrical length of the radiating tip while maintaining a small size (e.g., length) of the radiating tip. In other embodiments, adjusting the distance or gap between adjacent coils can allow the radiating tip to be tuned to operate at a predetermined or desired microwave frequency. In some examples, the gap may be uniform, but it should be understood that in other examples, the length of the gap may vary to accommodate the predetermined or desired operating frequency.

[0020] Optionally, the annular element may be electrically connected to the elongated element at either the proximal or distal end of the annular element. Adjusting the electrical connection point (feed point) between the annular element and the elongated element allows for further adjustment of the electrical length and properties of the radiating tip for operation at a predetermined or desired microwave frequency.

[0021] Optionally, the annular element may be electrically connected to the elongated element at the distal end of the elongated element.

[0022] Optionally, the radiating tip may also include a second annular element, which is wound around a portion of the elongated element distinct from the annular element and electrically connected to the elongated element. The parameters and dimensions of the second annular element may be configured in the same manner as described herein with respect to the annular element, but may be independently adjusted to be tuned to operate at a predetermined or desired microwave frequency. In one example, the first annular element may be electrically connected to the elongated element at its proximal end, and the second annular element may be electrically connected to the elongated element at its distal end, wherein the first annular element is positioned distal to the second annular element. For completeness, it should be noted that the second annular element is insulated from other components (such as the elongated element and the annular element) in a manner similar to that described above, except for one or more electrical connection points or contacts.

[0023] In some embodiments, the radiating tip may also include an intermediate element that is electrically connected (e.g., directly or indirectly) between the elongated element and the annular element. For completeness, it should be noted that the intermediate element is insulated from other components (such as the elongated element and the annular element) in a manner similar to that described above, except for one or more electrical connection points or contacts. For example, the intermediate element may be electrically connected to the elongated element at its distal end and / or at its distal end. Alternatively, the intermediate element may be electrically connected to the elongated element at its distal end and spaced apart from the distal end of the elongated element by a third distance (wherein the third distance may be, for example, between 1 mm and 5 mm). In one embodiment, the intermediate element may be electrically connected to the annular element at its distal end.

[0024] Optionally, the intermediate element may have a length between 3 mm and 20 mm.

[0025] Optionally, the intermediate element may include at least one fold, and the annular element may be wound around at least a portion of the intermediate element. For example, both the elongated element and the intermediate element may be located within one or more coils of the annular element. This also increases the electrical length of the radiating tip while ensuring that the size of the radiating tip can be minimized.

[0026] Optionally, the intermediate element can be integral with the ring element. For example, both the intermediate element and the ring element can be made from a single conductor (such as an insulated conductor).

[0027] Optionally, the electrosurgical instrument may also include an insulating membrane surrounding the radiating tip to prevent moisture and / or tissue ingress. This helps ensure the radiating tip operates as designed. In some embodiments, the membrane may also surround at least the distal portion of the coaxial feed cable.

[0028] Optionally, the outer diameter of the coaxial cable can be 5 mm or smaller, such as 2 mm or smaller.

[0029] The electrosurgical instruments discussed above can form part of a complete electrosurgical device for treating biological tissues. For example, the device may include: an electrosurgical generator arranged to supply microwave energy; and the electrosurgical instrument of the present invention, which may be connected to receive the microwave energy from the electrosurgical generator. The electrosurgical device may also include: a surgical endoscopic device (e.g., an endoscope) having a flexible cord for insertion into a patient's body, wherein the flexible cord has an instrument channel extending along its length, and wherein the electrosurgical instrument is sized to fit within the instrument channel.

[0030] In this specification, "microwave" can be used broadly to indicate a frequency range of 400 MHz to 100 GHz, but is preferably a range of 1 GHz to 60 GHz. Preferred calibration frequencies for microwave EM energy include: 433 MHz, 915 MHz, 2.45 GHz, 3.3 GHz, 5.8 GHz, 10 GHz, 14.5 GHz, and 24 GHz. 5.8 GHz may be preferred.

[0031] In this article, the terms "proximal" and "distal" refer to the ends of an electrosurgical instrument that are further away from and closer to the treatment site, respectively. Therefore, in use, the proximal end of the electrosurgical instrument is closer to the generator that provides RF and / or microwave energy, while the distal end is closer to the treatment site, i.e., the target tissue within the patient's body.

[0032] Unless the context otherwise indicates otherwise, the term “conductive” is used herein to mean conductive.

[0033] The term "longitudinal" as used below refers to the direction parallel to the coaxial transmission line along the length of the electrosurgical instrument. The term "inner" means radially closer to the center of the instrument (e.g., the axis). The term "outer" means radially further away from the center of the instrument (the axis).

[0034] The term “electrosurgery” is used in connection with instruments, devices, or tools that are used during surgical procedures and utilize microwave and / or radio frequency electromagnetic (EM) energy.

[0035] The present invention includes combinations of the described aspects and preferred features, except where such combinations are explicitly not permitted or should be explicitly avoided. Attached Figure Description

[0036] The implementation schemes and experiments illustrating the principles of the present invention will now be discussed with reference to the accompanying drawings.

[0037] Figure 1 This is a schematic diagram of an electrosurgical system for tissue ablation, as an embodiment of the present invention.

[0038] Figure 2 This is a schematic cross-section of an electrosurgical instrument as an embodiment of the present invention.

[0039] Figure 3 This is a schematic cross-section of an electrosurgical instrument as a second embodiment of the present invention.

[0040] Figure 4 This is a schematic cross-section of an electrosurgical device according to a third embodiment of the present invention.

[0041] Figure 5 This is a schematic cross-section of an electrosurgical device according to a fourth embodiment of the present invention.

[0042] Figure 6 This is a schematic cross-section of an electrosurgical device according to a fifth embodiment of the present invention.

[0043] Figure 7 This is a schematic cross-section of an electrosurgical device according to the sixth embodiment of the present invention.

[0044] Figure 8 The drawing is shown Figure 2 The curve of return loss versus frequency for electrosurgical instruments.

[0045] Figure 9 This is a schematic cross-section of an electrosurgical device according to the seventh embodiment of the present invention. Detailed Implementation

[0046] Various aspects and embodiments of the invention will now be discussed with reference to the accompanying drawings. Further aspects and embodiments will be apparent to those skilled in the art. All references herein are incorporated by way of citation.

[0047] Figure 1This is a schematic diagram of a complete electrosurgical system 100 capable of supplying microwave energy to the distal end of an invasive electrosurgical instrument. The system 100 includes a generator 102 for controllably supplying microwave energy. Suitable generators for this purpose are described in WO 2012 / 076844, which is incorporated herein by reference. The generator may be arranged to monitor reflected signals received from the instrument to determine a suitable power level for delivery. For example, the generator may be arranged to calculate impedance observed at the distal end of the instrument to determine an optimal power level for delivery. The generator may be arranged to deliver power in a series of pulses modulated to match the patient's respiratory cycle. This will allow power delivery to occur during lung deflation.

[0048] Generator 102 is connected to interface junction 106 via interface cable 104. Interface junction 106 may accommodate an instrument control mechanism, operable via a slide trigger 110, for example, to control the longitudinal (back-and-forth) movement of one or more control lines or push rods (not shown). If multiple control lines are present, multiple slide triggers may be present on the interface junction to provide comprehensive control. The function of interface junction 106 is to combine inputs from generator 102 and instrument control mechanism into a single flexible shaft 112 extending from the distal end of interface junction 106. In other embodiments, other types of inputs may also be connected to interface junction 106. For example, in some embodiments, a fluid supply may be connected to interface junction 106 to deliver fluid to the instrument.

[0049] The flexible shaft 112 can be inserted along the entire length of the instrument (working) channel through the endoscope 114.

[0050] The flexible shaft 112 has a distal assembly 118 (in Figure 1 (Not drawn to scale), the distal assembly is shaped to pass through the instrument channel of endoscope 114 and protrudes at the distal end of the endoscope's tube (e.g., into the patient's body). The distal assembly includes a radiation tip for delivering microwave energy to biological tissue. Tip configuration is discussed in more detail below.

[0051] The distal assembly 118 can be configured to have a maximum outer diameter suitable for passing through the working channel. Typically, the diameter of the working channel in a surgical endoscopic device (such as an endoscope) is less than 4.0 mm, for example, any one of 2.0 mm, 2.8 mm, 3.2 mm, 3.7 mm, or 3.8 mm. The length of the flexible shaft 112 can be equal to or greater than 0.3 m, for example, 2 m or longer. In other examples, the distal assembly 118 can be mounted at the distal end of the flexible shaft after it has been inserted through the working channel (and before the instrument cord is introduced into the patient). Alternatively, the flexible shaft 112 can be inserted into the working channel from the distal end before its proximal connection is made. In these arrangements, the distal assembly 118 may be larger than the size of the working channel of the surgical endoscopic device 114.

[0052] The system described above is one way to introduce an instrument into a patient's body. Other techniques are possible. For example, catheters can also be used to insert instruments.

[0053] Figure 2 A cross-sectional side view of an electrosurgical instrument 200, as an embodiment of the present invention, is shown. The distal end of the electrosurgical instrument may, for example, correspond to the distal assembly 118 discussed above. The electrosurgical instrument 200 includes a coaxial feed cable 202, which can be connected at its proximal end to a generator (such as generator 102) to transmit microwave energy. The coaxial feed cable 202 may be an interface cable 104 passing through a flexible shaft 112, as discussed above. The coaxial feed cable 202 includes an inner conductor and an outer conductor 204 separated by a dielectric material 206. The coaxial feed cable 202 is preferably low-loss for microwave energy. A choke (not shown) may be provided on the coaxial feed cable 202 to suppress the back propagation of microwave energy reflected from the distal end, and thus limit reverse heating along the device. In some embodiments, the coaxial feed cable 202 may also include a flexible outer sheath disposed around the outer conductor 204 to protect the coaxial feed cable 202. The outer sheath may be made of an insulating material to electrically isolate the outer conductor 204 from its surrounding environment. The outer sheath may be made of or coated with a non-stick material such as PTFE to prevent tissue from adhering to the device.

[0054] The outer diameter 205 of the coaxial cable 202 is selected to fit through the working channel of the surgical endoscope (e.g., as shown above in the reference). Figure 1 The surgical endoscope device (described above). Specifically, the outer diameter 205 is 1.4 mm to accommodate passage through a working channel with a diameter of 2 mm.

[0055] The radiating tip 210 is formed at the distal end of the coaxial feed cable 202. Figure 2The dashed line 211 illustrates the interface between the coaxial feed cable 202 and the radiating tip 210. The radiating tip 210 is arranged to receive microwave energy transmitted by the coaxial feed cable 202 and deliver said energy to biological tissue. The outer conductor 204 of the coaxial feed cable 202 terminates at the distal end of the coaxial feed cable 202; that is, the outer conductor 204 does not extend into the radiating tip 210. The radiating tip 210 includes a distal portion 212 of an inner conductor extending beyond the distal end of the coaxial feed cable 202. In particular, the distal portion 212 of the inner conductor extends beyond the distal end of the outer conductor 204 to form an elongated element of the radiating tip 210.

[0056] A protective sheath 230 is provided on the outer side of the radiating tip 210. The protective sheath 230 is an insulating film that forms the outer surface of the radiating tip 210 to prevent moisture and / or tissue ingress. The protective sheath 230 thus serves to insulate the radiating tip 210 and protect it from environmental influences. The protective sheath 230 may be made of or coated with a non-stick material (e.g., polytetrafluoroethylene, PTFE) to prevent tissue adhesion to the protective sheath. The protective sheath 230 also covers at least the distal portion of the coaxial feed cable 202, giving the instrument a smooth outer surface. In addition to the dimensions and other parameters of the radiating tip 210 discussed below, the thickness and material of the protective sheath 230 may also affect the return loss exhibited by the electrosurgical instrument 200, and thus allow selection to enable the radiating tip 210 to efficiently deliver energy to the tissue at a predetermined or desired operating frequency. For example, in the illustrated embodiment, the protective sheath 230 is made of polytetrafluoroethylene with a thickness of 0.1 mm (100 micrometers) and extends along almost the entire length of the coaxial cable 202, such that the combined outer diameter of the coaxial cable 202 and the protective sheath 230 is approximately 1.6 mm.

[0057] When microwave energy is delivered to the radiating tip 210, the radiating tip 210 can act as a microwave monopole antenna. To reduce the size of the radiating tip 210 while still enabling it to operate effectively at low microwave frequencies such as 915 MHz, the radiating tip 210 is configured to have an increased electrical length. Specifically, in addition to the elongated element formed by the distal portion 212 of the inner conductor, the radiating tip 210 includes a ring element 214 wound around a portion of the elongated element and electrically connected to it. In particular, in this embodiment, the ring element 214 is wound directly around the elongated element. By providing the ring element 214 to the radiating tip 210 in this way, the electrical length of the radiating tip 210 is increased, despite the limitation of the small diameter of the device. This allows the radiating tip 210 to effectively deliver microwave energy at a range of microwave frequencies (particularly including low microwave frequencies of approximately 915 MHz) into the tissue. In this example, the ring element 214 comprises enameled copper wire (i.e., copper wire coated with insulating varnish), which allows the ring element 214 to be tightly wound around the elongated element and in physical contact with the elongated element along its length. In some examples, adjacent coils are in contact with each other to further help increase the electrical length of the radiating tip 210. It should be understood that the elongated element 212 and the ring element 214 are insulated from each other by the enameled coating of the ring element 214, except at the electrical contact 218. In other embodiments, for example, the elongated element 212 may include such a coating, or the radiating tip 210 may include an additional insulating layer, which allows the elongated element 212 and the ring element 214 to approach each other (e.g., in physical contact) without creating an undesirable electrical connection.

[0058] Specific examples of the dimensional parameters associated with the radiating tip 210 will now be described, but it should be understood that these dimensional parameters can be adjusted in various embodiments of the invention to allow the radiating tip 210 to operate effectively as a microwave monopole antenna to match energy to tissue at one or more predetermined or desired microwave frequencies, including (but not limited to) 433 MHz, 915 MHz, 2.45 GHz, 3.3 GHz, 5.8 GHz, 10 GHz, 14.5 GHz, and 24 GHz.

[0059] The distal portion 212 of the inner conductor forms an elongated element with a length 215 of 10.6 mm and a diameter of 0.6 mm. That is, the inner conductor of the coaxial cable 202 extends beyond the outer conductor 204 by 10.6 mm to form the elongated element. The loop element 214 is spaced 216, 2.8 mm from the proximal end of the elongated element (and thus from the distal end of the outer conductor of the coaxial cable 205), and 1.8 mm from the distal end of the elongated element (and thus from the distal end of the radiating tip 210). Therefore, the length 219 of the loop element 214 is 6 mm. The outer diameter 220 of the loop element 214 is 1.6 mm. The number of turns of the loop element 214 can also be adjusted so that the return loss of the radiating tip 210 matches the desired microwave operating frequency. For example, the loop element 214 may comprise 13 turns of enameled copper wire with a diameter of 0.35 mm.

[0060] The annular element 214 is electrically connected to the distal portion 212 of the inner conductor via an electrical contact 218. For example, the electrical contact 218 may include solder or other electrical connectors. However, it should be understood that the annular element 214 may be electrically connected to the distal portion 212 of the inner conductor at other locations to alter the return loss exhibited by the radiating tip 210, for example as described with reference to further embodiments below.

[0061] Figure 3 This is a schematic cross-section of an electrosurgical instrument 300 as a second embodiment of the present invention. Many features of the electrosurgical instrument 300 are similar to... Figure 2 The electrosurgical instrument 200 shown has the same features as described above, and therefore the description of these features will not be repeated; only the differences will be described in detail below. Specifically, the difference in the radiating tip of the electrosurgical instrument 300 is that the annular element 214 is electrically connected to the elongated element 212 at its proximal end, rather than at its distal end. As... Figure 3 As shown, the electrical contact 318 connecting the annular element 214 to the elongated element 212 is thus positioned closer to the coaxial cable than the distal end of the radiating tip. Adjusting the position of the electrical connection between the annular element 214 and the elongated element 212 allows the electrosurgical instrument to be tuned to effectively deliver microwave energy to the tissue at a predetermined or desired operating frequency.

[0062] Figure 4 This is a schematic cross-section of an electrosurgical instrument 400 as a third embodiment of the present invention. Many features of the electrosurgical instrument 400 are similar to... Figure 2The electrosurgical instrument 200 shown has the same features as described above, and therefore the description of these features will not be repeated; only the differences will be described in detail below. In this embodiment, the electrosurgical instrument 400 also includes an intermediate element 412 that is electrically connected between the elongated element 212 and the annular element 214. That is, similar to the reference... Figure 2 and Figure 3 As in the described implementation, the annular element 214 is not directly electrically connected to the elongated element 212, but is electrically connected to the elongated element 212 via the intermediate element 421.

[0063] Intermediate element 421 comprises enameled copper wire connected at a first end to the distal tip of elongated element 212 via electrical contact 418, and at a second end to the distal end of annular element 214 (e.g., via another electrical contact such as solder). Providing intermediate element 421 in this manner further increases the electrical length of the radiating tip to provide desired return loss characteristics for delivering microwave energy of a desired or predetermined frequency into tissue. Figure 4 In the example shown, the enameled copper wire forming the intermediate element 421 is bent or folded and arranged such that the length of the wire extends from the distal tip of the elongated element 212 through the coil of the loop element 214 towards the coaxial cable, reaching the distal end of the loop element 214, and then back through the coil of the loop element 214 to the proximal end of the loop element 214, where a second electrical contact is positioned to electrically connect the intermediate element 421 to the loop element 214. That is, the loop element 214 is wound around both the intermediate element 421 and the elongated element 212. In this way, the electrical length of the radiating tip is increased by more than twice the length covered by the loop element 214. For example, using the reference above... Figure 3 The dimensions given for the described radiating tip are that the intermediate element 421 has a total length of 13.8 mm.

[0064] Figure 5 This is a schematic cross-section of an electrosurgical instrument 500 as a fourth embodiment of the present invention. Many features of the electrosurgical instrument 500 are similar to... Figure 4 The electrosurgical instrument 400 shown has the same features as described above, and therefore the description of these features will not be repeated; only the differences will be described below. Specifically, in this embodiment, the intermediate element 521 does not extend to the distal tip of the elongated element 212, but is arranged to terminate closer to the distal tip. This distance can be adjusted according to the frequency of the microwave energy that the electrosurgical instrument 500 intends to deliver to the tissue. Therefore, the electrical contact 518 that electrically connects the intermediate element 521 to the elongated element 212 is spaced apart from the distal tip of the elongated element 212. The intermediate element 521 includes a bent or folded wire and is electrically connected to the distal end of the annular element 214 in substantially the same manner as described above.

[0065] Figure 6 This is a schematic cross-section of an electrosurgical instrument 600, as a fifth embodiment of the present invention. Many features of the electrosurgical instrument 600 are similar to... Figure 2 The electrosurgical instrument 200 shown has the same features as described above, and therefore the description of these features will not be repeated; only the differences will be described in detail below. In particular, the electrosurgical instrument 600 includes two annular elements 614a, 614b, each wound around a portion of the elongated element 212 and electrically connected to the elongated element 212.

[0066] Specifically, the first annular element 614a is positioned proximal to the second annular element 614b. An electrical contact 618 is positioned between the first annular element 614a and the second annular element 614b to electrically connect the two annular elements 614a, 614b to the elongated element 212. Thus, the first annular element 614a is electrically connected to the elongated element 212 at its distal end, and the second annular element 614b is electrically connected to the elongated element 212 at its proximal end. The dimensions and parameters of the two annular elements 614a, 614b can be independently configured according to the frequency of the microwave energy that the electrosurgical instrument 600 intends to deliver to the tissue. For example, the length, number of turns, outer diameter, etc., of the two annular elements 614a, 614b, as described above... Figure 2 Any of the dimensions or parameters described.

[0067] Figure 7 This is a schematic cross-section of an electrosurgical instrument 700 as a sixth embodiment of the present invention. Many features of the electrosurgical instrument 700 are similar to... Figure 2 The electrosurgical instrument 200 shown has the same features as described above, and therefore the description of these features will not be repeated; only the differences will be described in detail below. Specifically, in this embodiment, the annular element 714 is electrically connected to the elongated element 212 and also to the outer conductor 204 of the coaxial feed cable. At its distal end, the annular element 714 is electrically connected to the elongated element 212 via a first electrical contact 718a at a location spaced apart from the distal tip of the elongated element 212. At its proximal end, the annular element 714 is electrically connected to the outer conductor 204 via a second electrical contact 718b.

[0068] Figure 8 Graph 800 is shown, which plots the relationship between return loss and frequency of an electrosurgical instrument according to an embodiment of the present invention, specifically, the electrosurgical instrument being referenced above. Figure 2The electrosurgical instrument 200 is described above. The dimensions and parameters of the radiating tip 210 have been selected to exhibit suitable return loss (i.e., return loss below a predetermined threshold, in this case less than -10 dB) at three microwave frequencies indicated by lines 801, 802, and 803. The first frequency indicated by line 801 is 915 MHz; the second frequency indicated by line 802 is 2.45 GHz; and the third frequency indicated by line 803 is 5.8 GHz. However, it can be seen by observing graph 800 that the radiating tip 210 also exhibits suitable return loss at other frequencies.

[0069] Figure 9 This is a schematic cross-section of an electrosurgical instrument 900, as a seventh embodiment of the present invention. Many features of the electrosurgical instrument 900 are similar to... Figure 2 The electrosurgical instrument 200 shown has the same features as described above, and therefore the description of these features will not be repeated; only the differences will be described in detail below. Specifically, in this embodiment, the annular element 914 is tightly coiled such that there is no gap or spacing between the loops of adjacent coils, turns, or wires. This may help to provide a compact radiating tip 910 with sufficient electrical length to operate at predetermined frequencies (e.g., including 433 MHz). It should be understood that the annular element 914 comprises the same insulated metal wire (i.e., enameled copper wire) as before, such that although the coils are in physical contact with adjacent coils, they are not in electrical contact.

[0070] As suggested above, the return loss characteristics of an electrosurgical tip can be altered by adjusting the size and parameters of the radiating tip. For example, increasing the number of turns in the toroidal element can typically shift the "zero" (minimum) of the return loss diagram to the left (i.e., to a lower frequency). As another example, increasing the length of the toroidal element (e.g., by increasing the distance between adjacent turns) can typically shift the zero to the right above approximately 4 GHz (i.e., to a higher frequency). Increasing the proximal gap length (i.e., the distance between the distal end of the outer conductor and the proximal end of the toroidal element) can typically shift the zero to the left below approximately 5 GHz (i.e., to a lower frequency). As a result of any changes in parameters or dimensions, the return loss exhibited by the electrosurgical tip can be confirmed through simulation to ensure that an appropriate return loss (e.g., less than -10 dB) is present at one or more predetermined or desired operating frequencies.

[0071] The features disclosed in the foregoing description, the appended claims, or the drawings, expressed in their particular form or by means of performing the disclosed functions or by methods or processes for obtaining the disclosed results, may, where appropriate, be used alone or in any combination of such features to implement the invention in its various forms.

[0072] While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when this disclosure is given. Therefore, the exemplary embodiments set forth above are to be considered illustrative rather than restrictive. Various changes may be made to the described embodiments without departing from the spirit and scope of the invention.

[0073] To avoid any doubt, any theoretical explanations provided herein are intended to enhance the reader's understanding. The inventor does not wish to be bound by any of these theoretical explanations.

[0074] Any chapter headings used in this article are for organizational purposes only and should not be construed as limiting the subject matter described.

[0075] Throughout the specification, including the appended claims, unless the context otherwise requires, the words “comprising” and “including” and their variations shall be understood to implicitly include the indicated integer or step or group of steps, but not exclude any other integer or step or group of steps.

[0076] It must be noted that, unless the context clearly indicates otherwise, the singular forms “a” and “the” as used in this specification and the appended claims include a plural referent. A range may be expressed herein as “about” a particular value and / or “about” another particular value. When such a range is expressed, another embodiment includes a range from one particular value and / or to another particular value. Similarly, when a value is expressed as an approximation using the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” with respect to numerical values ​​is optional and means, for example, + / - 10%.

Claims

1. An electrosurgical device comprising: A coaxial feed cable having an inner conductor, an outer conductor, and a dielectric material separating the inner conductor and the outer conductor, the coaxial feed cable being used to transmit microwave signals, and A radiating tip is disposed at the distal end of the coaxial feed cable to receive the microwave signal; The radiating tip includes: An elongated element, electrically connected to the inner conductor and extending in the longitudinal direction, and A ring-shaped element electrically connected to the elongated element, wherein the ring-shaped element is wound around at least a portion of the elongated element.

2. The electrosurgical instrument of claim 1, wherein the elongated element includes a distal portion of the inner conductor extending beyond the distal end of the outer conductor.

3. The electrosurgical instrument of claim 1 or claim 2, wherein the annular element comprises an insulated wire.

4. The electrosurgical instrument as claimed in any of the preceding claims, wherein the outer diameter of the radiating tip is less than 5 mm.

5. The electrosurgical instrument as claimed in any of the preceding claims, wherein the annular element is further electrically connected to the outer conductor of the coaxial feed cable.

6. The electrosurgical device as claimed in any of the preceding claims, wherein the annular element is spaced apart from the distal end of the outer conductor by a first distance.

7. The electrosurgical instrument of claim 6, wherein the first distance is between 1 mm and 5 mm.

8. The electrosurgical instrument of any of the preceding claims, wherein the annular element is spaced apart from the distal end of the elongated element by a second distance.

9. The electrosurgical instrument of claim 8, wherein the second distance is between 1 mm and 5 mm.

10. The electrosurgical instrument as claimed in any of the preceding claims, wherein the annular element has at least five coils.

11. The electrosurgical instrument as claimed in any of the preceding claims, wherein the annular element is tightly wound around the elongated element such that adjacent coils of the annular element are in contact with each other.

12. The electrosurgical instrument of any preceding claim, wherein the annular element is electrically connected to the elongated element at any of the following locations: The proximal end of the annular element; or The distal end of the annular element.

13. The electrosurgical instrument of any of the preceding claims, wherein the annular element is electrically connected to the elongated element at the distal end of the elongated element.

14. The electrosurgical instrument of any of the preceding claims, wherein the radiating tip further comprises a second annular element, wherein the second annular element is wound around a portion of the elongated element that is different from the annular element and is electrically connected to the elongated element.

15. The electrosurgical instrument of any one of claims 1 to 11, wherein the radiating tip further comprises an intermediate element electrically connected between the elongated element and the annular element.

16. The electrosurgical instrument of claim 15, wherein the intermediate element is electrically connected to the elongated element at the distal end of the elongated element and / or at the distal end of the intermediate element.

17. The electrosurgical instrument of claim 15, wherein the intermediate element is electrically connected to the elongated element at the distal end of the intermediate element and spaced apart from the distal end of the elongated element by a third distance.

18. The electrosurgical instrument of claim 17, wherein the third distance is between 1 mm and 5 mm.

19. The electrosurgical instrument of any one of claims 15 to 18, wherein the intermediate element is electrically connected to the annular element at the distal end of the annular element.

20. The electrosurgical instrument of any one of claims 15 to 19, wherein the intermediate element has a length between 3 mm and 20 mm.

21. The electrosurgical instrument of any one of claims 15 to 20, wherein the intermediate element comprises at least one fold, and the annular element is wound around at least a portion of the intermediate element.

22. The electrosurgical instrument according to any one of claims 15 to 21, wherein the intermediate element is integral with the annular element.

23. The electrosurgical device as claimed in any of the preceding claims further includes an insulating membrane surrounding the radiating tip to prevent moisture and / or tissue from entering.

24. The electrosurgical instrument as claimed in any of the preceding claims, wherein the outer diameter of the coaxial power supply cable is 5 mm or less.

25. An electrosurgical device for treating biological tissues, said electrosurgical device comprising: An electrosurgical generator, the electrosurgical generator being configured to supply microwave energy; as well as The electrosurgical device according to any of the preceding claims is connected to receive the microwave energy from the electrosurgical generator.

26. The electrosurgical device of claim 25, further comprising a surgical viewing device including a flexible cord having an instrument channel, wherein the electrosurgical instruments are sized to fit within the instrument channel.

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