CN100362969C - Electrosurgical Instruments - Google Patents

Abstract

An electrosurgical cutting blade ( 1 ) comprises a first electrode ( 2 ), a second electrode ( 3 ), and an electrical insulator ( 4 ) separating the first and second electrodes. The first and second electrodes have dissimilar characteristics (cross-sectional area, thermal conductivity etc.) such that the first electrode ( 2 ) is encouraged to become an active electrode and the second electrode ( 3 ) is encouraged to become a return electrode. The spacing between the first and second electrodes (between 0.25 mm and 3.0 mm) and the peak voltage supplied to the electrodes ( 2 and 3 ) are both selected such that arcing does not occur directly between the electrodes, but between the first electrode and the tissue at the target site. The arrangement is such that, in use, a thermal differential of at least 50 DEG C. is established between the first and second electrodes ( 2 and 3 ), such that the second electrode is maintained below a temperature of 70 DEG C. This is achieved either by thermally insulating the second electrode from the first electrode, and/or by transferring heat away from the second electrode, e.g. by conduction, forced cooling, or by means of a heat pipe ( 27 ).

Description

Electrosurgical Instruments

technical field

The present invention relates to bipolar electrosurgical cutting devices, such as surgical blades, and surgical systems, including electrosurgical generators and bipolar electrosurgical cutting devices. Such systems are commonly used in surgical procedures for the cutting of tissue, most often in "keyhole" or minimally invasive surgery, but also in "open" surgery ("open surgery"). "surgery).

Electrosurgical cutting devices fall into two categories, monopolar and bipolar. In monopolar devices, a radio frequency (RF) signal is supplied to an active electrode used to ablate biological tissue at the target point, completing an electrical circuit through a ground pad, usually a large area pad, attached to the patient's body away from the target point. in a certain position. In contrast, in a bipolar configuration, both the active electrode and the return electrode are on the cutting device, and current often flows from the active electrode to the return electrode via an arc formed therebetween.

Related application comparison

An early example of a bipolar RF cutting device is US4706667 published in Roos, in which the return or "neutral" electrode is placed in a position behind the active electrode. Details of the cut area or electrodes are given, and it is said that the neutral electrode is vertically spaced from the active electrode by 5 to 15 mm. In a series of patents including US3970088, US3987795 and US4043342, Morrison describes a cutting/coagulation device having a "one half quadrant differential" electrode configuration. These devices are said to be a cross between monopolar and bipolar devices, with the return electrode operational on the cutting device, but preferably with an area between 3 and 50 times larger than the cutting electrode. In one example (US3970088), an active electrode is covered with a porous, electrically insulating layer, which separates the active electrode from the biological tissue to be treated, and an electric arc is generated between the electrode and the biological tissue. This insulation is said to be between 0.125 and 0.25mm (0.005 and 0.01 inches) thick

In another series of patents (including US4674498, US4850353, US4862890 and US4958539), Stasz proposes various blade designs. These blades are designed with relatively small gaps between the electrodes so that when an RF signal is applied to the blades, an arc can be generated between them that cuts biological tissue. Because the arc is designed to be generated between the electrodes, the typical thickness of the insulating material separating the electrodes is between 0.025 and 0.075 millimeters (0.001 and 0.003 inches).

Summary of the invention

The present invention seeks to provide a bipolar blade which is an improvement over the prior art. Accordingly, there is provided an electrosurgical system comprising: a bipolar blade; a handle for securing the blade; and an electrosurgical signal generator for supplying a radio frequency voltage signal to the blade, the blade including first and second electrodes, and a septum The electrical insulators of the electrodes are spaced between 0.25 mm and 3.0 mm, and the electrosurgical signal generator is adapted to supply a radio frequency voltage signal to the blade, the radio frequency voltage signal having a substantially constant peak voltage value. The relationship between the peak voltage value and the spacing between the electrodes is such that the electric field strength between the electrodes is between 0.1 V/μm and 2.0 V/μm, and the first electrode has different characteristics from the second electrode so that The first electrode becomes the active electrode, leaving the second electrode to become the return electrode.

With respect to the term "blade," it is meant here to include all devices (P) 2-19-24 designed to enable both the active cutting electrode and the return electrode to enter the incision made by the instrument. It is not required that the cutting device have only the ability to cut axial incisions, indeed, as will be shown below, embodiments of the present invention have the ability to remove biological tissue laterally.

The first important function of the present invention is to carefully control the spacing between the electrodes and the electric field strength between them so that in the absence of biological tissue, a direct arc exists between the electrodes. For purposes of illustration, the spacing between electrodes is measured as the shortest electrical path between the electrodes. Thus, even if the electrodes are adjacent to each other such that the straight line distance between them is less than 0.25 mm, if the insulator separating the electrodes is such that the line cannot be used as a conductive path, then the "space" between the electrodes is the distance between the electrodes The shortest available conductive path. The electric field strength between the electrodes should preferably be between 0.15 volts/micron and 1.5 volts/micron, and typically between 0.2 volts/micron and 1.5 microns. In a preferred configuration, the separation between the first and second electrodes is between 0.25 mm and 1.0 mm, and the electric field strength between the electrodes is between 0.33 V/micron and 1.1 V/micron. Preferably, the electric field strength is such that the peak voltage across the first and second electrodes is less than 750 volts. This ensures that the electric field is strong enough to create an arc between the first electrode and the biological tissue, but not directly between the first and second electrodes.

However, even if direct arcing between the electrodes can be prevented, there is a potential problem if the two electrodes are similarly designed. In a bipolar cutting device, only one of the electrodes is presented at a high potential to biological tissue (and becomes the "active" electrode), while the remaining electrode is actually presented at the same potential as biological tissue (and becomes an "active" electrode). loop" electrode). Where the first and second electrodes are similar, which electrode becomes active is a matter of circumstance. If the device is activated prior to contact with the biological tissue, the electrode that first contacts the biological tissue will generally become the return electrode and the other electrode will become the active electrode. This means that in some cases one electrode is the active electrode and at other times the other electrode is the active electrode. Not only would this make it difficult for the surgeon to control the device (because there is no certainty where the cutting operation will actually occur), but it is likely that any one particular electrode will become the active electrode at some point.

Concentrate builds up on the surface of an electrode when it is active, which is not a problem while the electrode continues to be active, but it makes the electrode unsuitable for use as a return electrode. Thus, in cases where two similar electrodes are used, it is likely that, as each electrode becomes the active electrode at some times and the return electrode at other times, the build-up of concentrate on both electrodes will reduce the performance of the device. performance. Accordingly, the present invention provides a first electrode whose characteristics differ from those of a second electrode such that one electrode permanently assumes the role of the active electrode.

The different properties of the first electrode than the second electrode conveniently include a cross-sectional area of the electrode which is substantially substantially smaller than the second electrode. This helps to ensure that the first electrode has a relatively high initial impedance when in contact with biological tissue, while the relatively large second electrode has a relatively low initial impedance when in contact with biological tissue. This configuration facilitates making the first electrode the active electrode and the second electrode the return electrode.

The property of the first electrode which differs from the second electrode alternatively or additionally comprises a thermal conductivity of the electrode which is substantially lower than that of the second electrode. In addition to the initial impedance, the rate of rise in impedance is a factor that affects an electrode becoming an active electrode. This impedance will rise as the biological tissue dries, and the temperature of the electrodes will affect the rate of this drying. By selecting an electrode material with low thermal conductivity, the temperature of the electrode rises faster because less heat is transferred away from the portion of the electrode where energy can be transferred. This ensures a relatively fast drying rate, causes a relatively fast rise in impedance, and ensures that the first electrode remains the active electrode.

The different properties of the first electrode than the second electrode may further include a heat capacity of the electrode, the heat capacity of the first electrode being substantially lower than that of the second electrode. As previously mentioned, the low heat capacity helps to keep the temperature of the first electrode relatively high, ensuring that it remains an active electrode.

According to yet another first aspect of the present invention, there is provided an electrosurgical system comprising: a bipolar blade; a handle for securing said blade; and an electrosurgical signal generator for providing a radio frequency piezoelectric signal to the blade, the blade comprising The first and second electrodes, and the electrical insulator separating the electrodes are spaced between 0.25 mm and 1.0 mm, and the electrosurgical signal generator is adapted to supply a radio frequency voltage signal having a substantially constant peak voltage value to the blade, the The peak voltage values are between 250 volts and 600 volts respectively, and the first electrode has a different characteristic than the second electrode so that the first electrode becomes the active electrode and the second electrode becomes the return electrode.

Given a particular electrode isolation, it is ideal that the signal generator deliver the same peak voltage regardless of changing load conditions. Otherwise, a heavy load on the blade could stop it (otherwise, the voltage could be halved because the load impedance is close to the source impedance), while a light load could cause voltage overshoot and arcing directly between the electrodes.

The invention also pertains to bipolar blades comprising first and second electrodes and an electrical insulator space separating the electrodes, the first electrode having different properties than the second electrode so that the first electrode becomes the active electrode and the second electrode becomes a return electrode with a spacing between 0.25mm and 1.0mm so that when the electrodes are in contact with biological tissue and an electrosurgical cutting voltage is applied between them, no arcing occurs directly between the electrodes, also providing Means for ensuring that the temperature of the second electrode does not rise above 70°C.

Also to ensure that the second electrode does not become an active electrode, it is important to ensure that the temperature of the second electrode does not rise above 70 degrees Celsius, at which temperature biological tissue will start to stick to the electrode. The means for ensuring that the temperature of the second electrode does not rise above 70 degrees Celsius conveniently includes means for minimizing heat transfer from the first electrode to the second electrode. One way to achieve this is to ensure that the first electrode is made of a material with a relatively poor thermal conductivity, preferably the material should have a thermal conductivity of less than 20 W/m.K. By making the first electrode a poor thermal conductor, heat is not effectively transferred from the active point of the electrode to the second electrode, thus helping to prevent the temperature rise of the second electrode.

Alternatively or additionally, the transfer of heat from the first electrode to the second electrode is prevented by separating the two electrodes by constituting an electrical insulator of a material having a relatively poor thermal conductivity, preferably a material with a thermal conductivity less than 40W/m.K. This in turn helps prevent heat generated at the first electrode from being transferred to the second electrode.

Another way to prevent heat transfer is to mount the first electrode in intermittent fashion to the electrical insulator.

Preferably, the first electrode should be mounted to the electrical insulator at one or more point contact locations, and/or have a plurality of small holes punched in the first electrode to reduce the percentage of contact with the electrical insulator.

A preferred material for the first electrode is tantalum. When tantalum is used as the active electrode, it rapidly becomes covered with an oxide material. This tantalum oxide is a poor conductor of electricity, which helps the first electrode maintain a high resistance state to biological tissue and remain an active electrode.

Another way to help ensure that the temperature of the second electrode does not rise above 70 degrees Celsius is to maximize the heat transfer away from the second electrode. This allows heat transferred from the first electrode to the second electrode to be rapidly transferred away from the second electrode before the temperature of the second electrode rises rapidly. One way to achieve this is to form the second electrode from a material with a relatively high thermal conductivity, preferably the material should have a thermal conductivity greater than 150 W/m.K.

The second electrode may conveniently be provided with additional cooling means to remove heat therefrom, such as heat pipes mounted on the second electrode, or forcing cooling fluid along a path in contact with the second electrode. Whichever method is used, it is desirable in use that the temperature difference between the first and second electrodes be at least 50°C, and preferably should be between 100°C and 200°C.

A third electrode suitable for coagulating biological tissue should preferably be additionally provided. This coagulation electrode is conveniently mounted to a second electrode with an additional electrical insulator in between. It is necessary to ensure that the temperature of the condensation electrode rises too high, so if the condensation electrode is installed to the second electrode (which is designed according to the technology and is a good thermal conductor), it should preferably be arranged so that heat can easily pass through Additional electrical insulators. This can be accomplished by forming the additional insulation from a material with a relatively high thermal conductivity, or more typically, if the additional insulation is not a good conductor of heat, by ensuring that the additional insulation is relatively thin, usually no more than about 50 microns. accomplish. In this approach, the heat transfer across the additional insulator is greater than 5 mW/mm ² .K.

In one configuration, the second and third electrodes are formed as conductive electrodes on an insulating substrate. Thus, when the blade with the first electrode is used for cutting biological tissue, both the second and third electrodes function as return electrodes. When the blade is used to coagulate biological tissue, a coagulation RF signal is applied between the second and third electrodes.

According to a further aspect of the present invention there is provided a bipolar blade comprising: first and second electrodes and an electrical insulator space separating the electrodes, the first electrode having a different characteristic than the second electrode such that the first electrode becomes For the active electrode, and the second electrode becomes the return electrode, the interval between the electrodes should be between 0.25 mm and 1.0 mm, so that when the electrodes are in contact with the biological tissue and the electrosurgical cutting voltage is applied between them, there will be no direct contact between them. An electric arc is generated between the electrodes, and a third electrode, suitable for coagulating biological tissue, is additionally provided, separated from the second electrode by an additional insulator.

The second and third electrodes are conveniently provided in a side-by-side arrangement with an additional insulator between them. Alternatively, the second and third electrodes are configured as electrode layers in a sandwich structure with an additional insulator between them. In one convenient arrangement, the first, second and third electrodes are arranged as electrode layers in a sandwich structure with an insulator layer therebetween.

In one configuration, a first of the second and third electrodes is provided with a cut-out and the other of the second and third electrodes is provided with a protrusion. Preferably, the cut-out portion of one electrode accommodates the protruding portion of the other electrode, typically with the protruding portion embedded in the electrode, surrounding said cut-out portion.

Alternatively, the first, second and third electrodes are configured as electrode layers in a sandwich structure with the first electrode in the middle of the structure and an insulator layer between each electrode. In one configuration, the cross-section of the second and third electrodes is substantially semicircular, while the first electrode protrudes slightly beyond the perimeter of the second and third electrodes.

According to a final aspect of the present invention, there is provided a method of cutting biological tissue at a target point, the method comprising: providing a bipolar blade comprising first and second electrodes and an electrical insulator spacer separating the electrodes, the first The electrode has different characteristics than the second electrode so that the first electrode becomes the active electrode and the second electrode becomes the return electrode; the blade is directed to a position relative to the target point so that the second electrode is at the target point in contact with the The biological tissue is contacted so that the first electrode is adjacent thereto; an electrosurgical cutting voltage is provided to the blade, the electrosurgical voltage and the spacing between the first and second electrodes are such that there is no gap between the first and second electrodes Electric arc can be generated in the air between the first and target point biological tissue, and electric current flows to the second electrode through the biological tissue; and prevent the accumulation of heat in the second electrode, so that the temperature of the second electrode is will rise to over 70 degrees Celsius. Preferably, the method is such that both the first and second electrodes contact the biological tissue at the target point substantially simultaneously.

Brief description of the drawings

The invention will be described with reference to the accompanying drawings, by way of example only, in which:

Fig. 1 is a schematic diagram of an electrosurgical system constituted according to the present invention;

Figure 2 is a schematic cross-sectional view of an electrosurgical blade constructed in accordance with the present invention;

Fig. 3 is a functional block diagram showing the transverse cutting action of Fig. 2 blade;

4a to 4d are schematic cross-sectional views of an alternative embodiment of an electrosurgical blade constructed in accordance with the present invention;

Figures 5a and 5b are schematic illustrations of electrosurgical blades constructed in accordance with the present invention, incorporating cooling means; and

Figures 6a and 6b, and Figures 7 to 11 are alternative electrosurgical blades constructed in accordance with the present invention incorporating additional coagulation electrodes.

Detailed description of the invention

Referring to FIG. 1 , a signal generator 10 includes an output socket 10S for outputting radio frequency (RF) to an instrument 12 via a connecting cord 14 . The signal generator 10 is activated from the instrument 12 via a connection via a cord 14 or via a foot switch unit 16 which is connected via a foot switch connection cord 18 to the rear of the RF signal generator as shown. In this illustrative embodiment, heel switch unit 16 contains two foot switches 16A and 16B for selecting the coagulation mode and the cutting mode of signal generator 10, respectively. The front panel of the radio frequency signal generator contains buttons 20 and 22 for setting coagulation and cutting power levels respectively, which levels are displayed on a display 24 . A button 26 is provided as an alternative for selecting between coagulation and cutting modes.

Referring to Figure 2, instrument 12 includes a blade, shown generally at 1, and includes a generally planar first electrode 2, a larger second electrode 3, and an electrical insulator 4 separating the first and second electrodes. The first electrode 2 consists of stainless steel, which has a thermal conductivity of 18 W/mK (although alternative materials such as nichrome could also be used). The second electrode 3 is made of a material with high thermal conductivity, such as copper with a thermal conductivity of 400 W/mK (alternative materials include silver and aluminum). The surface of the second electrode 3 is plated with a bicoefficient harmonious material such as chromium alloy, or with an alternative non-oxidizing material such as nickel, gold, platinum, palladium, stainless steel, titanium nitride or tungsten disulphide. The electrical insulator 4 consists of a ceramic material such as Al ₂ O ₃ , typically having a thermal conductivity of 30 W/mK. Other possible materials can be used for the insulator 4, which have a sufficiently low thermal conductivity. These materials include: boron nitride, porcelain, steatite, zirconia, polytetrafluoroethylene, reinforced mica, silicone rubber or other ceramic materials such as foam ceramics or moldable glass ceramics such as sold under the trademark MACOR.

A conductive lead 5 is connected to the first electrode 2 and a lead 6 is connected to the second electrode 3 . The RF output from the signal generator 10 is connected to the blade 1 via leads 5 and 6 so that a radio frequency signal with a substantially constant peak voltage (typically about 400V) is present between the first and second electrodes 2 and 3 . Referring to Figure 3, when the blade 1 is brought into contact with the biological tissue 7 at the target point, the RF voltage will create an arc between the electrode and the surface of the biological tissue. Because the first electrode 2 has a smaller cross-sectional area and has lower heat capacity and thermal conductivity than the second electrode 3, the first electrode will act as an active electrode and connect the electrode to the biological tissue 7. Arcing occurs. The current will flow through the biological tissue 7 to the second electrode 3, which assumes the role of a return electrode. The active electrode will cut the biological tissue, and the blade can move through the biological tissue. The blade 1 can be used to cut the biological tissue 7, or can be moved laterally in the direction of the arrow 8 in Figure 3 to remove a layer of biological tissue.

During cutting, considerable heat will be generated at the active electrode 2, and the temperature of the electrode can rise to 100°C-250°C. However, less heat is transferred to the second electrode 3 due to the poor thermal conductivity of the insulator 4 . Even if heat is not transferred to the second electrode 3 , the high thermal conductivity of the copper material means that a lot of heat is transferred away from the electrode surface and into the electrode body 9 . This helps to ensure that a temperature differential is maintained between the first electrode 2 and the second electrode 3, and that the temperature of the second electrode is kept below 70°C whenever possible. This ensures that, whenever the instrument 12 is activated, the second electrode 2 remains the return electrode and that the biological tissue does not start sticking to the electrode 3 .

Besides providing the insulator 4 with a rather low thermal conductivity, it has the advantage of ensuring that the contact of the first electrode 2 with the insulator is as small as possible. In FIG. 2 , the electrode 2 is not secured to the insulator 4 and the electrode 3 in a continuous fashion, but is secured by contact pins generally indicated at 11 at one or more points. Figure 4a shows another design of the blade, in which the first electrode 2 is shaped so that it is only intermittently in contact with the insulator 4 along its length, and in region 13 the electrode is shaped outwards from the insulator 14 into arched. This helps to further minimize heat transfer from the first electrode 2 to the second electrode 3 via the insulator 4 . Fig. 4b shows another arrangement in which the first electrode is perforated 15 in a mesh format. Again, this helps to minimize the transfer of heat from the first electrode to the insulator 4 . FIG. 4 c shows another configuration in which there is an additional corrugated electrode layer 17 between the first electrode 2 and the insulator 4 . As mentioned above, this helps to prevent the heat generated at the first electrode 2 from being transferred to the second electrode 3 so as to maintain the thermal difference therebetween.

FIG. 4d shows a variant of the blade of FIG. 2 in which the blade is shaped as a hook 19 . The first electrode 2, the second electrode 3 and the insulator 4 are all hook-shaped, and the operation of the device is substantially as described with reference to FIG. 2 . The hook electrode is particularly suitable for separating biological tissue, whether used as a cold ablation instrument without RF excitation, or as an RF cutting instrument. The biological tissue remains within the corners 20 of the hooks 19 when manipulating or cutting.

Regardless of which electrode design is used, it is an advantage if the heat transferred from the first electrode 2 to the second electrode 3 can be transferred away from the biological tissue contacting surface of the electrode 3 . In the blade of Figure 2, the second electrode 3 is made of a large amount of copper which conducts heat away from the electrode tip. The function of the electrode 3 can be further enhanced by cooling means as described in Figures 5a and 5b. In FIG. 5 a the second electrode 3 is mounted on a heat pipe indicated at 27 . The heat pipe 27 comprises a hollow sealed tube 28 with a distal end 29 adjacent to the electrode 3 and a proximal end 30 within the handle of the instrument 12 . The middle of the sealed tube 28 contains a cavity 31 containing a low boiling temperature liquid 32 such as acetone or alcohol. In use, heat from the electrodes 3 vaporizes the liquid 32 at the distal end 29 of the sealed tube, and this vapor then condenses at the proximal end 30 of the sealed tube, as this is relatively cooler than the distal end 29 . In this way, heat is transferred from the distal end of the electrode 3 to its proximal end, from where further heat can be dissipated by the handle of the instrument 12 .

Figure 5b shows an alternative configuration in which the heat pipe of Figure 5a is replaced by a forced cooling system, shown generally at 33. The cooling system 33 includes a sealed tube 34 which in turn has a distal end 29 and a proximal end 30 . The sealing tube 34 includes a coaxial inner tube 35 defining an inner cavity 36 and an outer cavity 37 . Holes are perforated in the inner tube 35 toward the distal end of the sealing tube to communicate the inner and outer lumens 36 and 37 with each other. In use, the self-contained pump 38 moves cooling fluid 39 along the inner lumen 36 to the distal end 39 and back through the outer lumen 37 for continued recirculation. Electrode 3 heats the circulating fluid, which carries heat to proximal end 30 of sealed tube 34 . In this way, regardless of the rise in temperature of the first electrode 2, the temperature of the second electrode is kept low.

The remaining figures show a configuration equipped with a third electrode 40 to allow coagulation or drying of biological tissue 7 . In Fig. 6a, the blade 1 is shown as constructed in Fig. 4b, and like reference numerals are used to designate like parts. A third electrode 40 is mounted on the second electrode 3 on the side opposite to the first electrode 2 and on an additional electrical insulator 41 . An RF signal may be applied from the signal generator 10 to the third electrode 40 through the lead wire 42 . The insulator 41 is made of a thin layer of silicone rubber, alternative materials for the insulator 41 include polyamide, PEEK (polyether ether ketone) or PVC (polyvinyl chloride) materials. This thin layer ensures that heat can be transferred through the silicone rubber layer and that the coagulation electrode 40 can benefit from the thermally conductive properties of the second electrode 3 . In this way, despite any heat previously generated by the first electrode 2, the coagulation electrode 40 is able to maintain a relatively low temperature. In use, biological tissue is cut as previously described. When coagulation is desired instead of cutting, the third electrode 40 is placed in contact with the biological tissue 7 and a coagulation RF signal is applied between the second electrode 3 and the third electrode 40 .

Figure 6b shows an alternative embodiment in which the second electrode 3 and the third electrode 40 are metallised tracks on a substrate 43 of aluminum nitride material, as previously described, the material is Electrically insulating and good thermal conductor, allowing heat to be transferred away from the second and third electrodes.

FIG. 7 shows a configuration in which the first electrode 2 is located in the middle of the second and third electrodes 3 and 40 . Both electrodes 3 and 40 are approximately semicircular in cross-section and form a generally cylindrical structure with the first electrode 2 protruding slightly from the middle region thereon. The insulating layer 4 separates the first electrode 2 from the second electrode 3 , and the insulating layer 41 separates the first electrode 2 from the third electrode 40 . When a user intends to use the instrument for cutting biological tissue, the signal generator 10 applies a cutting RF signal between the first electrode 2 and one or both of the second or third electrodes 3,40. Conversely, when the user intends to use the instrument to coagulate biological tissue, the signal generator 10 applies a coagulation RF signal between the second electrode 3 and the third electrode 40 . The relatively large surface area of the electrodes 3 and 40 allows efficient coagulation of biological tissue while allowing heat transfer away during cutting, as previously described.

Figure 8 shows another alternative device design in which the second and third electrodes 3 and 40 are placed side by side. The first electrode 2 is substantially planar and an insulating layer 4 separates the first electrode from the second and third electrodes 3 and 40 on the other side of the device. The electrodes 3 and 40 are arranged side by side with an insulating portion 41 in between. As previously stated, the instrument is capable of cutting biological tissue with RF signals between the first electrode 2 and one of the second or third electrodes 3, 40, or alternatively coagulating with RF signals between the second and third electrodes. biological tissue.

Figure 9 shows another embodiment in which the first, second and third electrodes are arranged as a multi-electrode layer in a "sandwich" arrangement. The first electrode 2 is shown as the top layer in Fig. 9, the third electrode 40 is the bottom layer, and the second electrode 3 is sandwiched between these two layers. The insulating layers 4 and 41 are used to isolate the first, second, and third electrodes, respectively. This configuration provides blade 1 with a relatively thick cutting edge, which is designed to facilitate coagulation of biological tissue.

Figure 10 shows a configuration that exploits the functionality of this sandwich and side-by-side electrode structure. The electrodes are again arranged in a sandwich structure, and the first electrode 2 shown in FIG. 10 is on top instead of the top shown in FIG. 9 . The second electrode 3 is again in the middle of the interlayer, separated from the first electrode by the insulating layer 4 . The third electrode 40, shown as the top electrode in Fig. 10, contains a central recess through which the raised portion 50 of the second electrode 3 can protrude. The second and third electrodes are separated by the insulator 41 , and the top surface of the protruding portion 50 is embedded in the top of the third electrode 40 . This configuration allows the side or top surface of the blade 1 as shown in Figure 10 to be used to coagulate biological tissue.

Figure 11 shows a configuration in which the tip of the blade 1 comprises a first electrode 2 in the middle with insulating layers 4 and 41 on both sides. Each of the insulating layers 4 and 41 respectively has a beveled distal end, shown at 51 and 52 respectively. The second electrode is mounted to the insulating layer 4, the beveled end 51 causing the second electrode to be placed in a position rearward from the first electrode 2 along the blade axis. In a similar way that the third electrode 40 is mounted to the insulator 41 , the beveled end 52 also causes the third electrode to be placed in a position axially rearward from the first electrode 2 . Beveled ends 51 and 52 allow for a minimum separation of 0.25 millimeters between the first electrode and the second and third electrodes (shown as "x" in FIG. 11 ), while maintaining an overall elongated profile for blade 1 . The first electrode 2 can be embedded in the ends of the first and second insulating layers 4 and 41, or can slightly protrude therefrom, as shown in FIG. 11 . As previously mentioned, heat transfer from the first electrode can be reduced by a number of techniques, including mounting the electrode to the insulating layer in an intermittent manner, or drilling the electrode with small holes to reduce heat transfer.

The present invention relies on careful selection of a number of design parameters, including the spacing between the first and second electrodes, the voltage applied thereto, the dimensions and materials chosen for the electrodes and the electrical insulator or insulator. This careful selection should ensure that there is no direct arcing between the electrodes, that only one electrode becomes the active electrode, and that the return electrode remain relatively small by preventing heat from being transferred to the return electrode or by transferring heat that should be transferred to the second electrode. low temperature.

The relatively cool return electrode ensures that there is little or no thermal damage to the biological tissue adjacent to the return electrode of the device, while the biological tissue helps to transfer heat away from the return electrode.

Claims (17)

1. bipolar blade comprises:

First and second electrodes (2,3); And

The electrical insulator (4) that separates described first and second electrodes,

Described first electrode has and the different characteristic of described second electrode, so that described first electrode becomes active electrode, and makes described second electrode become loop electrode,

The described first and second interelectrode intervals are between 0.25 millimeter and 1.0 millimeters, contact with biological tissue and when being applied to electrosurgical cut voltage between them with described first and second electrodes of box lunch, can directly between described first and second electrode, not produce electric arc

Third electrode (40) is suitable for coagulate tissue, by further insulator (41) described third electrode and described second electrode separated,

It is characterized in that, with described the first, the second and third electrode be configured to electrode layer in the sandwich, in the middle of wherein said first electrode is positioned at, between every layer of electrode layer, contain insulator layer,

Wherein, described first electrode is around the periphery of its periphery outstanding a little described second and third electrode.

2. bipolar blade as claimed in claim 1, it is characterized in that, the characteristic of described first electrode (2) different with described second electrode (3) comprises the cross-sectional area of described electrode, and the described cross-sectional area of described first electrode is less than the cross-sectional area of described second electrode.

3. bipolar blade as claimed in claim 1 is characterized in that, the characteristic of described first electrode (2) different with described second electrode (3) comprises the thermal conductivity of described electrode, and the described thermal conductivity of described first electrode is lower than the thermal conductivity of described second electrode.

4. bipolar blade as claimed in claim 1 is characterized in that, the characteristic of described first electrode (2) different with described second electrode (3) comprises the thermal capacity of described electrode, and the described thermal capacity of described first electrode is lower than the thermal capacity of described second electrode.

5. as the described bipolar blade of one of claim 1 to 4, it is characterized in that, described second and third electrode (3,40) be semi-circular cross-section.

6. bipolar blade as claimed in claim 1 is characterized in that, further comprises being used to guarantee that the temperature of described second electrode (3) can not rise to the device that surpasses 70 degree Celsius.

7. bipolar blade as claimed in claim 6, it is characterized in that, the described temperature that is used to guarantee described second electrode (3) can not rise to the devices that surpass 70 degree Celsius and comprise, is used to make the heat that is delivered to described second electrode from described first electrode (2) to reduce to minimum device.

8. bipolar blade as claimed in claim 7 is characterized in that, described electrical insulator (4) is to be made by a kind of material that thermal conductivity is on duty mutually, and the thermal conductivity of described material is less than 40W/m.K.

9. bipolar blade as claimed in claim 7 is characterized in that, described first electrode (2) is installed to described electrical insulator (4) with intermittent mode.

10. as bipolar blade as described in the claim 9, it is characterized in that described first electrode (2) is installed to described electrical insulator (4) at one or more somes contact positions.

11. bipolar blade as claimed in claim 10 is characterized in that, is equipped with many apertures on described first electrode (2), to reduce the percentage ratio that contacts with described electrical insulator (4).

12. bipolar blade as claimed in claim 6 is characterized in that, the described temperature that is used to guarantee described second electrode (3) can not rise to the described devices that surpass 70 degree Celsius and comprise, is used to make biography to reach maximum device from the heat of described second electrode.

13. bipolar blade as claimed in claim 12 is characterized in that, described second electrode (3) is to be made by the quite high a kind of material of thermal conductivity, and the thermal conductivity of described material is greater than 150W/m.K.

14. bipolar blade as claimed in claim 13 is characterized in that, described second electrode (3) is equipped with additional chiller (29), to remove the heat on it.

15. bipolar blade as claimed in claim 14 is characterized in that described configuration is such, the heat transmission of crossing described further insulator (41) is greater than 5mW/mm ².K.

16. Electrosurgical system, it is characterized in that, comprise: bipolar blade (1), the handle (12) of fixing described blade, and the electrosurgery signal generator, being used for the radio-frequency voltage signal is offered described bipolar blade, described bipolar blade is as any bipolar blade in the claim 1 to 15, and described electrosurgery signal generator is suitable for the radio-frequency voltage signal is applied to described bipolar blade, and described radio-frequency voltage signal contains constant crest voltage value.

17. Electrosurgical system as claimed in claim 16 is characterized in that, described crest voltage value is between 250 volts and 600 volts.

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