ENERGY DELIVERY DEVICE, GENERATOR DEVICE, ELECTROSURGICAL APPARATUS, AND METHOD FOR REDUCING LEAKAGE CURRENT USING THE ENERGY DELIVERY DEVICE - Patent application

Abstract

Various embodiments provide an energy transfer device for transferring high frequency electromagnetic energy and / or microwave electromagnetic energy. The device includes a first conductive line and a second conductive line configured to transfer high frequency electromagnetic energy and / or microwave electromagnetic energy having a first frequency. The device also includes an electric element providing a first leakage capacitance. The first leakage capacitance is between the first conductive line and ground and / or between the second conductive line and ground. The device further includes a tuning circuit including an inductor unit and a capacitor unit having a capacitance to ground. The inductor unit and the capacitor unit are connected in series between ground and either the first conductive line or the second conductive line. The inductor unit has a tuning inductance such that the tuning circuit and the first leakage capacitance form a resonant circuit having a resonant frequency matched to the first frequency. Some other embodiments relate to corresponding generators for generating and / or transferring high frequency electromagnetic energy and / or microwave electromagnetic energy, corresponding apparatus, and corresponding methods for reducing leakage current.

Description

[Technical field]

[0001] The present invention relates to an energy delivery device for delivering radio frequency (RF) electromagnetic energy and / or microwave electromagnetic energy, the energy delivery device comprising a first conductive wire for delivering radio frequency electromagnetic energy and / or microwave electromagnetic energy having a first frequency and a second conductive wire. Furthermore, the present invention relates to a generator device for generating and / or delivering radio frequency electromagnetic energy and / or microwave electromagnetic energy comprising the energy delivery device. The present invention also relates to an electrosurgical apparatus comprising the generator device. Finally, the present invention relates to a method for reducing leakage currents using an energy delivery device for delivering radio frequency electromagnetic energy and / or microwave electromagnetic energy. [Background technology]

[0002] The standard BS EN60601-2-2:2009 requires the following: Patient circuits specifically designed for bipolar applications shall be isolated from earth and other applied parts at both high and low frequencies.

[0003] · The high frequency (hf) leakage current flowing from either pole of the bipolar output through a 200 ohm non-inductive resistor on each line to the earth wire and to the neutral electrode shall not exceed a value which would produce a power equal to 1% of the maximum bipolar rated output power through the 200 ohm non-inductive resistor, with all output controls set to maximum.

[0004] The leakage current in each of the two lines of a bipolar power supply to the ground and neutral terminals is often caused by streaks, leakage, or unwanted capacitance between the opposing lines and ground.

[0005] Isolation of the bipolar power supply from the ground and neutral terminals is often achieved using an isolation transformer, which may also introduce capacitance, about half of which may be contributed to the leakage capacitance on each line of the bipolar power supply.

[0006] In one example, at 400 kHz, with a 1 kΩ load, the total leakage capacitance on one line that would keep the power across a 200 Ω test resistor on the opposing line below a set limit would be approximately 80 pF.

[0007] The isolation transformer and associated circuitry may have a capacitance of 60pF, which contributes about 30pF to each line, allowing an additional 50pF of capacitance to ground.

[0008] An object of the present invention is to reduce leakage currents caused by leakage capacitance in galvanic DC isolated electrical radio frequency (RF) or microwave frequency devices. Summary of the Invention [Problem to be solved by the invention]

[0009] Achieving this object is the subject matter of the independent claims. Preferred embodiments of the invention are defined in the dependent claims. [Means for solving the problem]

[0010] Most generally, the present invention provides a connection of an inductor and a capacitor connected in series between one line of an RF and / or microwave bipolar power supply and a ground or neutral terminal.

[0011] According to a first aspect of the present invention, there is provided an energy transfer device for transferring high frequency electromagnetic energy and / or microwave electromagnetic energy. The energy transfer device includes a first conductive line and a second conductive line configured to transfer high frequency electromagnetic energy and / or microwave electromagnetic energy having a first frequency, an electric element providing a first leakage capacitance, and a tuning circuit including an inductor unit and a capacitor unit having a ground capacitance. The first leakage capacitance is between the first conductive line and ground and / or between the second conductive line and ground. The inductor unit and the capacitor unit are connected (or coupled) in series between ground and either the first conductive line or the second conductive line. The inductor unit has a tuning inductance such that the tuning circuit and the first leakage capacitance form a resonant circuit having a resonance frequency (or resonance frequency) matched to the first frequency.

[0012] According to a second aspect of the present invention, there is provided a generator device for generating and / or transmitting high frequency and / or microwave electromagnetic energy, comprising a generator unit configured to generate high frequency and / or microwave electromagnetic energy of a first frequency, and an energy transmission device, the energy transmission device being electrically coupled (e.g. directly or indirectly connected) to the generator unit.

[0013] According to a third aspect of the present invention there is provided an electrosurgical apparatus comprising a generator device and a radiating device for emitting high frequency electromagnetic energy and / or microwave electromagnetic energy.

[0014] The present invention provides a reliable and effective reduction or substantially complete cancellation of leakage current.

[0015] The term "electrosurgery" is used in reference to an instrument, device, or tool that may be used during surgery and utilizes radio frequency (RF) electromagnetic (EM) energy and / or microwave EM energy to treat a treatment zone. As used herein, microwave EM energy may refer to electromagnetic energy having a (stable, fixed) frequency in the range of 300 MHz to 100 GHz, preferably in the range of 1 GHz to 60 GHz. Preferred spot frequencies of microwave EM energy include 915 MHz, 2.45 GHz, 5.8 GHz, 14.5 GHz, and 24 GHz. 5.8 GHz may be preferred. Radio frequency (RF) may refer to RF energy having a (stable, fixed) frequency in the range of 20 kHz to about 1 GHz. 400 kHz may be preferred.

[0016] In use, the treatment zone may include biological tissue within the lungs, uterus, gastrointestinal tract, or other organs of a patient. Microwave energy can cause dielectric heating of biological tissue that can be used to ablate tissue within a localized volume around the radiating device. Thus, by directly inserting the radiating device into the fibroid treatment zone, including, for example, a tumor, lesion, or fibroid, microwave energy can be applied to tissue within the treatment zone to ablate it. Thus, microwave EM energy delivered by the energy delivery device can be radiated from the radiating device into the treatment zone to coagulate and / or ablate the treatment zone. RF energy can be used to cut tissue within the treatment zone.

[0017] The radiating device may include an RF antenna and / or a microwave antenna. The antenna may be a conventional monopole antenna formed at the end of the energy transfer device. The energy transfer device may include a (coaxial) transmission line, such as a conventional coaxial cable. The inner conductor of the coaxial cable may be connected to a radiating device or antenna capable of radiating RF and / or microwave energy. The radiating device may include one or more dielectric materials to provide dielectric loading of the antenna to enhance or shape the energy emission profile of the microwave antenna. The coaxial feed cable may include an outer conductor separated from the inner conductor by a dielectric material.

[0018] The radiating device may include one or more electrodes (e.g., two electrodes), at least one of which is connected or coupled to the first conductive line or the second conductive line. For example, the first electrode is connected or coupled to the first conductive line and the second electrode is connected or coupled to the second conductive line. The electrodes may be spaced apart from each other to allow for placement of tissue therebetween. Upon application of RF energy, the tissue between the electrodes may be cut.

[0019] Electrosurgical devices can be used to apply RF and / or microwave energy to matter, such as biological tissue, fluids, or other materials, in the vicinity of the emitting device.

[0020] The electrosurgical device may be an endoscopic electrosurgical device. For example, the electrosurgical device may be sized and shaped to be configured for insertion into a scoping device. The scoping device may be used to guide a emitting device of the electrosurgical device to a treatment zone, i.e., the emitting device is positioned near the treatment zone. The emitting device may exit the scoping device during use of the electrosurgical device. For example, the emitting device protrudes from a distal end of the scoping device.

[0021] The generator device may include means for generating and / or transmitting RF electromagnetic energy and / or microwave EM energy. The generator unit may be configured to generate electromagnetic radiation of one fixed single frequency or of multiple fixed single frequencies. Alternatively or additionally, the generator unit may be tunable to generate electromagnetic radiation of various frequencies, for example within a continuous frequency range between a minimum frequency and a maximum frequency. The generator unit may be connected to a power source providing energy for generating the RF electromagnetic energy and / or microwave EM energy.

[0022] The generator unit is electrically and / or electronically connected (directly or indirectly) to the energy delivery device. Preferably, the generator unit generates RF EM and / or microwave EM energy that is transferred by the energy delivery device to the radiating device, where the RF EM and / or microwave energy is radiated to the treatment zone.

[0023] A first conductive wire and / or a second conductive wire may be provided for transmitting energy. In this embodiment, the first and second conductive wires may be connected to a generator unit. Alternatively, one of the first conductive wire and the second conductive wire may be grounded or connected to a neutral terminal. In this embodiment, the grounded one of the first conductive wire and the second conductive wire may not be electrically connected to the generator unit.

[0024] The first conductive wire and / or the second conductive wire may comprise wires that are electrically insulated from one another (e.g., twisted pair cables). As described above, the first conductive wire and / or the second conductive wire may form a coaxial transmission line, whereby the inner conductor is disposed coaxially with the outer conductor and separated from one another by a dielectric layer. The outer conductor may completely surround the inner conductor in a circumferential direction.

[0025] The first conductive wire and / or the second conductive wire may be configured to transmit electromagnetic radiation within a frequency range from a minimum frequency to a maximum frequency, where the first conductive wire and / or the second conductive wire are configured to transmit electromagnetic radiation at a first frequency, which may be a frequency generated by the generator unit.

[0026] The energy transfer device may be electrically isolated from the ground or neutral terminal when it is subjected to a constant voltage, such as during a test routine, resulting in a direct current (DC). Thus, no leakage current occurs when the energy transfer device is subjected to a constant voltage (or DC operation).

[0027] The electric element does not provide leakage current during DC operation, i.e. when a zero frequency current is transmitted by the energy transfer device, which means that the electric element is also isolated to the ground or neutral terminal in theoretical DC operation of the energy transfer device.

[0028] The energy transfer device, the generator unit, and / or the generator device may be DC isolated, i.e., there is no leakage current when exposed to a constant voltage that may cause a DC current to flow.

[0029] However, the electrical element does produce leakage current during alternating current (AC) operation of the energy transfer device, such as when transferring RF or microwave energy. This is because the electrical element acts as a capacitor (first leakage capacitor having a first leakage capacitance) between the first conductive line and / or the second conductive line and the ground / neutral terminal, functions as a capacitor, or has (provides) the properties of a capacitor (these properties of capacitance provide DC isolation). It should be noted that the first leakage capacitor does not necessarily refer to an actual capacitor component that is an electrical component or part of an electrical component, but instead refers to any circuit or circuit element that functions as a capacitor (e.g., provides the properties of a capacitor) during use. That is, the first leakage capacitor may be provided by a transformer, a multiplexer, or some other electrical component that is not a capacitor component. Needless to say, the first leakage capacitor could also be or include a capacitor component. In either case, the first leakage capacitor may be represented in a circuit diagram of the energy transfer device to indicate the first leakage capacitance provided by the electrical element or energy transfer device.

[0030] The electrical element may provide further capacitor properties. However, for this description, only those capacitor properties occurring between the first / second conductive wire and the earth / neutral terminal that interact with the EM energy transferred at the first frequency to give rise to detectable, non-negligible, significant or relevant leakage currents are relevant. Thus, negligible first leakage capacitances (between the first / second conductive wire and the earth / neutral terminal) that do not significantly interact with the first frequency may not be considered in the present invention. For example, negligible leakage currents caused by the further capacitance of an electrical element providing less than 0.1%, 0.05% or 0.01% of the maximum bipolar rated output power (according to BS EN 60601-2-2:2009 - see above) at the first frequency into a 200 Ω (non-inductive) test resistor may not be considered in the present invention. Those negligible first leakage capacitances or negligible leakage currents are present but can be considered tolerable or their effect can be considered negligible. In other words, in the absence of a tuning element, the non-negligible first leakage capacitances, which are the subject of the present invention, give rise to non-negligible leakage currents (or power at a 200 Ω (non-inductive) test resistor) at the first frequency that are more than 0.1%, 0.05% or 0.01% of the maximum bipolar rated output power (according to BS EN 60601-2-2:2009 - see above). Those non-negligible first leakage capacitances or non-negligible leakage currents, if present, are considered to be non-tolerable and their effect can be considered significant. The present invention therefore aims to reduce or substantially cancel the sum of such non-negligible leakage capacitances and negligible leakage capacitances or the sum of non-negligible leakage currents and negligible leakage currents. Please note that unless otherwise specified, references herein to "leakage current" or "leakage capacitance" should be understood as "the sum of non-negligible leakage capacitance and negligible leakage capacitance" and "the sum of non-negligible leakage current and negligible leakage current," respectively.However, it should also be noted that since negligible capacitance or negligible leakage current may not be an issue, the above defined references to "leakage current" or "leakage capacitance" may in fact refer to "non-negligible leakage current" and "non-negligible leakage capacitance," respectively. In other words, the present invention aims to reduce or offset an unacceptable or non-negligible total capacitance (the sum of all leakage capacitances that can be represented by a first leakage capacitor with a first leakage capacitance) and / or a total leakage current (the sum of all leakage currents) to a negligible or acceptable value.

[0031] The term "electrical element" should be understood as any electrical component (e.g., circuit component) and / or any combination of interconnected electrical components (e.g., one or more circuits) of an energy transfer device that provides a first leakage capacitance (causing leakage current) between a first conductive line and a ground / neutral terminal and / or a second conductive line and a ground / neutral terminal during AC operation, and provides electrical isolation between the first conductive line and a ground / neutral terminal and / or a second conductive line and a ground / neutral terminal during DC operation.

[0032] Thus, leakage currents, although intended to be avoided, are inherently present due to the interaction of some of the electrical components of an energy transfer device with each other or with the ground / neutral terminals. "Leakage" may be considered the unintended and / or unwanted transfer of electrical energy across a boundary that is normally considered to be insulating. "Leakage" may also refer to the unwanted transfer of energy from one circuit to another.

[0033] Thus, the electrical element may be any part and / or any combination of interconnected electrical components of the energy transfer structure that provides a leakage capacitance (causing leakage current). The electrical element may affect only the first conductive line, only the second conductive line, or both the first and second conductive lines.

[0034] The electrical element may be permanently connected or electrically coupled to the first and / or second conductive lines. The electrical element may also be configured to be selectively connected, disconnected, or electrically coupled and decoupled to the first and / or second conductive lines, for example, using a switch. The electrical element may include a replaceable element that can be connected to the energy transfer structure, such as a tool or a radiating device.

[0035] For example, the electrical elements may include isolation transformers, microwave chokes, and / or multiplexers.

[0036] The isolation transformer (or output transformer) may transfer the generated RF and / or microwave energy onto the energy transfer device or between sections of the energy transfer device. The isolation transformer (or output transformer) may be coupled or connected between the generator unit (e.g., the first generator and / or the second generator, respectively) and the first conductive wire and / or the second conductive wire. Alternatively, the isolation transformer (or output transformer) may be coupled or connected between sections of the first conductive wire and / or the second conductive wire. The isolation transformer may provide for electrical isolation of the first conductive wire and / or the second conductive wire (or sections thereof) from a power source of the generator unit, e.g., from a power source of the first generator and / or the second generator.

[0037] An isolation transformer may also be provided between the generator unit and the first conductive line and / or the second conductive line. For example, each generator (first generator, second generator, etc.) of the generator unit comprises a respective isolation transformer. Thus, when the first generator is connected to the energy transfer device (e.g., using or via a multiplexer), the leakage capacitance changes due to the isolation transformer and the leakage capacitance of the first generator compared to a connection state in which the second generator is connected to the energy transfer device.

[0038] An isolation transformer may be a transformer used to transfer power from a source of alternating current (AC) power (e.g., a generator unit) to some equipment or device (e.g., an energy transfer device) while isolating the powered device from the source, for example for safety reasons. An isolation transformer may provide galvanic isolation; that is, there is no conductive path between the source and the load. This isolation may be used to protect against electric shock, to suppress electrical noise, and / or to transfer power between two circuits that should not be connected. Isolation transformers may be constructed with special isolation between the primary and secondary circuits and may be specified to withstand high voltages between the windings. An isolation transformer may include two coils or windings, one connected to a first conductive wire and / or a second conductive wire. This coil or winding may provide a first leakage capacitance.

[0039] The outer conductor of a coaxial transmission line may be important to prevent microwave leakage. Introducing a break in the outer conductor may require a device called a microwave choke to prevent leakage. This break in the outer conductor acts or functions as a leakage capacitor. This construction of a microwave choke may function as a leakage capacitor because low capacitance and low leakage tend to be opposing goals for insulating microwave chokes.

[0040] A multiplexer may be a diplexer and may combine inputs from various sources into one output. For example, a multiplexer (or diplexer) may be used to combine the outputs of three or more (two) generators into a single output that is connected or coupled to the first conductive line and / or the second conductive line.

[0041] As different generators and / or isolation transformers are connected to the energy transfer device, different connection states of the multiplexer may cause an increase or change in the leakage capacitance. In other words, the combination of the multiplexer, the generator unit, and / or the isolation transformer may be considered as an electrical component whose leakage capacitance is variable depending on the connection state of the multiplexer. Thus, the electrical element may provide a first leakage capacitance and a second leakage capacitance.

[0042] An inductor unit may include one or more inductors and / or other electrical components that provide inductance. The combined inductance of the components of an inductor unit provides a tuning inductance. Similarly, a capacitor unit may include one or more capacitors and / or other electrical components that provide capacitance. The combined capacitance of the electrical components of a capacitance unit provides a capacitance to ground.

[0043] The inductor unit may also include one or more tuning capacitors that provide a tuning capacitance for the inductor unit.

[0044] The capacitor unit provides DC isolation of the tuned circuit with respect to the first conductive line or the second conductive line. Thus, the capacitor unit may be considered as a DC isolator. Optionally, the capacitor unit is electrically connected between the inductor unit and a ground / neutral terminal, or vice versa. Further, optionally, the inductor unit may be connected between the capacitors of the capacitor unit.

[0045] The tuning circuit and the first leakage capacitor / capacitance are arranged such that the tuning circuit and the first leakage capacitor / capacitance form a parallel resonant circuit or an LC circuit, which means that both the tuning circuit and the first leakage capacitor / capacitance are connected in parallel between the ground / neutral terminal and the first conductive line and / or the second conductive line.

[0046] The following equation describes the impedance of a parallel resonant circuit:

[0047]

number

[0048] ω0 is the angular resonant frequency of the resonant circuit (ω0=2πf0, where f0 is the resonant frequency).

[0049]

number

[0050] C is a first leakage capacitance; L is a tuning inductance compensated for by a ground capacitance; and ω is a first angular frequency, which may be an angular frequency provided by a generator device.

[0051] A more precise description of the angular resonant frequency is given in equation (3) below.

[0052]

number

[0053] C is the first leakage capacitance, L is the tuning capacitance, and C S is the capacitance to ground. Therefore, L in equation (2) is effectively less than the tuning inductance L, as is evident from equation (3).

[0054] The first frequency ω is the resonant frequency ω of the resonant circuit. 0にIt is clear from equation (1) that the closer the impedance, the higher the inductance of the resonant circuit. A higher impedance means less leakage current flows through the first leakage capacitor. Therefore, tuning or setting the tuning impedance, tuning capacitance, and / or ground capacitance according to equation (2) so that ω0 ≈ ω effectively reduces or substantially cancels the leakage current through the electrical component.

[0055] Thus, matching the resonant frequency of the resonant circuit with the first frequency means that the impedance of the resulting resonant circuit is high, so that the leakage current is reduced to an acceptable level or to a level set by standards and / or industry standards. For example, the power due to leakage current (or the power into a 200 Ω (non-inductive) test resistor) at the first frequency is less than 1%, 0.75%, 0.5%, 0.25%, or 0.01% of the maximum bipolar rated output power (according to BS EN 60601-2-2:2009 - see above). For example, |f-f0|≦1 kHz, 5 kHz, or 10 kHz. Alternatively, |f-f0| / f0 may be less than 0.25%, 1.25%, or 2.5%, where f is the first frequency and f0 is the resonant frequency of the resonant circuit.

[0056] A first leakage capacitance may be measured and the tuning inductance, capacitance to ground, and / or tuning capacitance are set or tuned / modified / changed accordingly. Alternatively or additionally, the leakage current is monitored (via a 200 Ω test resistor) and the tuning inductance, capacitance to ground, and / or tuning capacitor are modified to reduce the leakage current. This embodiment does not require explicit measurement of the leakage current.

[0057] In summary, the purpose of the inductor unit / tuning circuit is to create a parallel resonant circuit with a first leakage capacitance to increase the total impedance to a very high value, resulting in a significant reduction in the effective leakage capacitance and a reduction in power across a 200 Ω test resistor connected between the other line (the first conductive line and the second conductive line that do not have any electrical elements connected to them) and the ground or neutral terminal.

[0058] The capacitance to ground of the capacitor unit is optionally at least 10, 100, or 1000 times greater than the first leakage capacitance and / or the tuning capacitance of the first leakage capacitor. For example, the tuning capacitance is about 1 μF.

[0059] If the capacitance is significantly larger than the first leakage capacitance and / or the tuning capacitance, the capacitor unit has little effect on equation (1). Instead, the capacitor unit provides DC isolation for the tuned circuit, but is essentially negligible for the calculation of impedance according to equation (1). This is due to the fact that a very large ground capacitance does not interact, or only very little, with the first frequency. For example, for operation at 400 kHz, a ground capacitance of about 1 μF in series with an inductor unit having a tuning inductance of about 1 mH would be adequate to offset a first leakage capacitance of about 100 pF.

[0060] A further interpretation of this is that the resonant circuit formed solely by the inductor unit and the capacitor unit has a resonant frequency that is significantly offset from the first frequency, so that the resonant circuit can be neglected near the first frequency. The resonant frequency of the resonant circuit formed solely by the inductor unit and the capacitor unit is offset from the first frequency due to the large capacitance to ground.

[0061] In an optional embodiment, the inductor unit includes one tuning inductor having a tuning inductance, or two or more tuning inductors permanently connected or coupled to each other to commonly provide a tuning inductance.

[0062] In this embodiment, the tuning inductance is fixed, which is appropriate when the generator device generates a fixed first frequency or when the generator device generates a frequency close to the first frequency, for example offset from the first frequency by ±3%, ±5%, or ±10%. In the latter case, the tuning circuit may still be effective in reducing leakage current.

[0063] Furthermore, the first leakage capacitance may also vary for different tools used with the generator device and / or energy delivery device and / or for different microwave generators attached to the RF generator device. These variations may only slightly alter the first leakage capacitance such that the leakage current can still be effectively reduced by the tuned circuit.

[0064] By providing two or more tuning inductors, it is possible to set the tuning inductance using an inductor having a predetermined frequency, for example by connecting or coupling the tuning inductances in series and / or in parallel to set the tuning inductance appropriately.

[0065] Furthermore, the inductor unit may include one or more tuning capacitors for setting the resonant frequency of the resonant circuit to a first frequency, which is equivalent to changing the resonant frequency of the tuning circuit. Thus, for example, when a suitable setting value of the resonant frequency cannot be achieved by setting the tuning inductance alone, the one or more tuning capacitors provide a different means for changing the resonant frequency of the resonant circuit.

[0066] In an optional embodiment, the inductor unit includes two or more tuning inductors and a switch unit, where the switch unit is configured to selectively electrically connect or couple the one or more tuning inductors to the capacitor unit to selectively change a tuning inductance of the tuning circuit. Alternatively, the inductor unit includes at least one tuning inductor, at least one tuning capacitor, and a switch unit, where the switch unit is configured to selectively electrically connect the one or more tuning inductors and / or the one or more tuning capacitors to selectively change a resonant frequency of the resonant circuit (or a tuning circuit that is an LC circuit in which the inductor unit and the capacitor unit are connected in series).

[0067] In the above embodiment, the switch unit is used to connect or disconnect one or more tuning inductors and / or one or more tuning capacitors to or from the tuning circuit, in particular to a tuning inductor that is permanently connected to the capacitor unit, In this way the tuning inductance or the resonant frequency of the resonant circuit can be switched between two or more values.

[0068] The switch unit may include one or more electrical switches. In a first state of the switch, one or more of the tuning capacitors and / or one or more of the tuning inductors are connected / coupled in series to the capacitor unit (either in parallel or in series with a tuning inductor that is permanently connected / coupled in series to the capacitor unit (also in the second state of the switch)). In a second state of the switch, one or more of the tuning capacitors and / or one or more of the tuning inductors are not connected / coupled to the capacitor unit. Thus, one or more of the tuning capacitors and / or one or more of the tuning inductors are not part of the resonant circuit. In short, in the second state of the switch, the number of electrical components contributing to the tuning circuit is different than when the switch is in the first state. As a result, the tuning inductance and / or the resonant frequency of the resonant circuit is different depending on whether the switch is in the first state or in the second state. The first and second states may correspond to open and closed states, respectively, or vice versa. For example, in a closed state, the switch provides a bypass to the tuning inductor and / or the tuning capacitor.

[0069] The more switches that are provided, the more resonant frequencies that can be selected by selectively opening or closing each switch.

[0070] In optional embodiments, the first conductive line and the second conductive line are configured to transmit high frequency electromagnetic energy and / or microwave electromagnetic energy having a second frequency different from the first frequency, and / or the electrical element provides a second leakage capacitance different from the first leakage capacitance, and optionally the tuning circuit is configured to selectively vary a resonant frequency of the resonant circuit such that the resonant frequency is matched with the first frequency or the second frequency, and / or the tuning circuit is configured to selectively vary the resonant circuit such that the tuning circuit and the first or second leakage capacitance form respective resonant frequencies (e.g., first and second resonant frequencies) matched with the first frequency.

[0071] Matching the resonant frequency of the resonant circuit with the second frequency and / or the second leakage capacitance means that the impedance of the resulting resonant circuit is high, so that the leakage current is reduced to an acceptable level or to a level set by standards and / or industry standards. For example, the power due to the leakage current (or the power into a 200 Ω (non-inductive) test resistor) at the second frequency is less than 1%, 0.75%, 0.5%, 0.25%, or 0.01% of the maximum bipolar rated output power (according to BS EN 60601-2-2:2009 - see above). For example, |f-f0|≦10Hz, 50Hz, or 100Hz. Alternatively, |f-f0| / f may be less than 1%, 3%, 5%, or 10%, where f is the second frequency and f0 is the resonant frequency of the resonant circuit.

[0072] The second frequency may correspond to a second frequency generated by the generator unit. The generator unit may be configured to alternately generate either the first frequency or the second frequency. For example, the generator unit may include an input device or interface for selecting the first frequency or the second frequency to be generated.

[0073] Depending on the selection of the first or second frequency, the switch unit or the single switch is set to either a first state or a second state. In the first state, the tuning inductance or the resonant frequency of the resonant circuit is matched to the first frequency. In the second state, the tuning inductance or the resonant frequency of the resonant circuit is matched to the second frequency.

[0074] Optionally, the generator unit may be configured to generate a third, fourth etc. frequency and the first conductive line and the second conductive line are configured to transmit high frequency and / or microwave electromagnetic energy having the third, fourth etc. frequency, in which case the switch unit may include a further switch for selectively setting the tuning capacitance or resonant frequency of the resonant circuit to the third, fourth etc. frequency using the principles outlined above.

[0075] Similarly, the leakage capacitance may change due to the connection or disconnection of one or more different electrical elements to the energy transfer structure (e.g., a generator), replacement of an electrical component (e.g., replacement of a radiating device), and / or internal changes to an electrical component (e.g., a different set value), such that the first leakage capacitance changes to a second leakage capacitance. The same features, characteristics, and / or functions described in relation to the first leakage capacitance equally apply to the second leakage capacitance. In particular, the second leakage capacitance may be represented by a second leakage capacitor.

[0076] The second leakage capacitance may be present in place of or in addition to the first leakage capacitance. Additionally, an additional leakage capacitance may be electrically connected to the first leakage capacitance to provide a second leakage capacitance. Changes in the leakage capacitance require changes in the tuning circuit, as well as changes in the first and second frequencies.

[0077] In other words, the change from the first leakage capacitance to the second leakage capacitance causes the resonant frequency of the resonant circuit to change from the first resonant frequency to the second resonant frequency. The second resonant frequency of the resonant circuit may no longer be matched to the first frequency transmitted by the energy transfer device. The tuning circuit may then need to be reset or retuned so that the second resonant frequency is matched to the first resonant frequency. For example, the power due to the leakage current (or the power at a 200Ω (non-inductive) test resistor) caused by the second leakage capacitance at the first frequency is less than 1%, 0.75%, 0.5%, 0.25%, or 0.01% of the maximum bipolar rated output power (according to BS EN 60601-2-2:2009 - see above). For example, |f-f0|≦10Hz, 50Hz, or 100Hz. Alternatively, |f-f0| / f may be less than 1%, 3%, 5%, or 10%, where f is the first frequency and f0 is the second resonant frequency of the resonant circuit.

[0078] It is also possible that a change in the frequency transmitted by the energy delivery device (e.g., from a first frequency to a second frequency) and a change in leakage capacitance (e.g., from a first leakage capacitance to a second leakage capacitance causing a change from a first resonant frequency to a second resonant frequency) occur simultaneously, where the second frequency is matched with the second resonant frequency.

[0079] In an optional embodiment, the inductor unit includes at least one tuning inductor and / or at least one tuning capacitor that is tunable or variable to vary the resonant frequency of the tuning circuit.

[0080] In further embodiments, the first conductive line and the second conductive line are configured to transmit high frequency electromagnetic energy and / or microwave electromagnetic energy having a second frequency, and / or the electrical element provides a second leakage capacitance different from the first leakage capacitance, and optionally the tuning circuit is configured to be tuned or changed to selectively change the resonant frequency of the resonant circuit such that the resonant frequency is matched with the first frequency or the second frequency, and / or the tuning circuit is configured to selectively change the resonant circuit such that the tuning circuit and the first or second leakage capacitances form respective resonant frequencies (e.g., first and second resonant frequencies) matched with the first frequency.

[0081] Since the first leakage capacitance is assumed to be constant, the change in the resonant frequency of the tuning circuit is equal to the change in the resonant frequency of the resonant circuit. In other words, the resonant circuit includes the tuning circuit and the first leakage capacitance.

[0082] A tunable tuning inductor is configured to change or vary its inductance, and a tunable tuning capacitor is configured to change or vary its capacitance. In other words, the tuning or varying is performed on the tuning inductor and / or tuning capacitor itself, and no external switches of the tuning inductor and / or tuning capacitor are used. Thus, by tuning or varying the tuning inductance of the tuning inductor and / or the tuning capacitance of the tuning capacitor, the resonant frequency of the resonant circuit is changed. Optionally, a continuous or stepwise change of the tuning inductance of the tuning inductor and / or the tuning capacitance of the tuning capacitor is possible. A tunable tuning inductor and a tunable tuning capacitor may be considered as a variable tuning inductor (or a tuning inductor with a variable / tunable inductance) and a variable tuning capacitor (a tuning capacitor with a variable / tunable capacitance), respectively.

[0083] The tunable tuning inductor may include a "'Slotten' 1 mm Tunable Inductor" from Coilcraft Inc. The tunable tuning capacitor may include a "Φ 7.5 mm Film Dielectric Trimmer" from Vishay Intertechnology, Inc.

[0084] This allows the resonant frequency according to equation (2) or (3) to be matched or approximated to the frequency generated by the generator device, especially if the generator device allows for the generation of frequencies in a continuous range of frequencies.

[0085] In an optional embodiment, the energy transfer device further includes an additional tunable or variable capacitor unit having an additional capacitance, the additional capacitor unit being connected in series between ground and either the first conductive line or the second conductive line.

[0086] The additional capacitor unit and the tuning circuit are connected in parallel between ground and either the first conductive line or the second conductive line. The additional capacitor unit may include one or more capacitors connected in series. For example, the first additional capacitor may be tunable and the second additional capacitor may not be tunable (i.e., have a fixed capacitor). The tunable inductor features, characteristics, and / or embodiments described above may equally apply to the tunable additional capacitor unit. The provision of two more capacitors with the additional capacitor unit may be done for redundancy reasons.

[0087] The additional capacitor unit can be considered as changing the resonant frequency of the resonant circuit and / or changing the resonant frequency of the tuned circuit, and therefore the additional capacitor unit can be used instead of or in addition to the tunable inductor unit to change the resonant frequency.

[0088] The leakage capacitance may be very small, so the amount of capacitance variation required may be very small. For example, the additional capacitance may be approximately the same as the first or second leakage capacitance. This may be suitable for a variable or tunable capacitor.

[0089] In an optional embodiment, the capacitor unit may have features and characteristics of an additional capacitor unit. One of the capacitors of the capacitor unit may be tunable or variable. Thus, the capacitor unit includes two or more capacitors, and the ground capacitance may be variable or tunable by tuning / changing the tunable / variable capacitor(s) of the capacitor of the capacitor unit. The tunable / variable capacitor(s) of the capacitor of the capacitor unit may have features and / or characteristics of the (tunable) first additional capacitor of the additional capacitor unit. When the ground capacitance varies, the resonant frequency of the tuning circuit varies, as is clear from the equations provided above. A variable ground capacitance may be provided in addition to or as an alternative to the above-mentioned embodiments for changing the resonant frequency of the tuning circuit.

[0090] In optional embodiments, the first conductive line and the second conductive line are configured to transmit high frequency electromagnetic energy and / or microwave electromagnetic energy having a second frequency different from the first frequency, and / or the electrical element provides a second capacitance different from the first leakage capacitance, and the additional capacitor unit is optionally configured to be altered to selectively change a resonant frequency of the resonant circuit such that the resonant frequency is matched with the first frequency or the second frequency, and / or the additional capacitor unit is configured to selectively change the tuning circuit such that the tuning circuit and the first or second leakage capacitance form a resonant circuit having a respective resonant frequency matched with the first frequency.

[0091] Thus, the additional capacitor unit can be used to vary the effective inductance L in equation (2). Similar features, characteristics and / or embodiments described for the tunable inductor unit apply to the additional tunable capacitor unit.

[0092] In an optional embodiment, the energy delivery device further includes a measurement device for measuring and / or monitoring a leakage current induced by the first leakage capacitance.

[0093] The measuring device may include any means for determining if there is leakage current and / or loss of power due to leakage. For example, the measuring device determines a current power consumption and compares the current power consumption to a predetermined power consumption. This comparison may indicate loss of power due to leakage. Additionally, the measuring device may include electrical circuitry for directly measuring leakage current. For example, current flowing to ground (leakage current) is measured by connecting a meter (such as a galvanometer) of the measuring device in series with the ground connection of the energy delivery device. The measuring device may include a leakage current transformer. In a further embodiment, the measuring device includes a 200 Ω test resistor and an ammeter or galvanometer for measuring the current flowing through the 200 Ω test resistor.

[0094] The leakage current can be measured using a measuring device (e.g., a current transformer or galvanometer) or by measuring the voltage across the test resistor and using the formula I=V / R, where I is the current flowing through the test resistor, R is the resistance of the test resistor, and U is the voltage drop across the test resistor. The test resistor is there primarily for compliance testing. In normal use, the test resistor may not be connected to an energy transfer structure. The test resistor is there to stand in for the human body and may provide this kind of resistive path to the earth wire or neutral terminal and should not have a high leakage current passing through it.

[0095] It may be useful to use a test resistor during setup since the test resistor will not be in place during use, however, the procedures described here and below may be used to set up an automated library of settings for each device or setup used to allow switching / tuning to a predetermined minimum leakage current configuration.

[0096] In any embodiment, the energy delivery device includes a display device for displaying the leakage current measured by the measurement device, and / or an input device for varying the resonant frequency of the resonant circuit by tuning at least one tuning inductor and / or at least one tuning capacitor.

[0097] The present embodiment relates to manual tuning of a tuning circuit or manual reduction of leakage current. The display device may include a display and / or a screen and is electrically and / or electronically connected / coupled to the measurement device. The display device displays the leakage current measured or determined by the measurement device. Thus, the measured or determined leakage current is displayed to a user.

[0098] The input device allows for changing or modifying the resonant frequency of the tuned circuit and therefore the resonant circuit. The input device may include one or more buttons, dials, and / or levers operatively connected to the tuning inductor and / or tuning capacitor. When the user manipulates the input device, the resonant frequency of the tuned circuit changes. Thus, manipulation of the input device causes a change in leakage current. The leakage current can be minimized by properly manipulating the input device and thus by properly setting the resonant frequency of the tuned circuit.

[0099] In an optional embodiment, the energy transfer device further includes a controller configured to tune and / or vary a tuning inductance of the at least one tuning inductor and / or a tuning capacitance of the at least one tuning capacitor to change a resonant frequency of the resonant circuit based on the leakage current measured by the measurement device.

[0100] The present embodiment relates to automatic tuning of a tuning / resonant circuit or automatic reduction of leakage current. The control device may include a processor and a memory in which an algorithm or program executed by the processor is stored. The control device may include a computer or the like. The control device may include an actuator, such as an electric motor, for tuning the inductor unit (such as a tuning inductor and / or a tuning capacitor). The actuator may be controlled by the processor. Furthermore, the control device is electrically or electronically connected to a measuring device to receive a signal indicative of the leakage current. The program, method or algorithm stored in the memory and executed by the processor minimizes or reduces the leakage current based on measurements received from the measuring device.

[0101] The control device is electronically and / or electrically connected to the tuned circuit to change the resonant frequency of the tuned circuit. For example, an actuator of the control device is connected to the input device to change the resonant frequency of the tuned circuit. The control device changes the resonant frequency of the tuned circuit such that leakage current is reduced or minimized.

[0102] In an optional embodiment, the capacitor unit includes two or more capacitors, optionally connected together in series.

[0103] At least two capacitors are connected in series between the inductor unit and the earth / neutral terminal. Because the capacitor unit may be a safety-critical component to the DC isolation, a second capacitor, a third capacitor, etc. may be provided to provide redundancy in case the first capacitor is shorted.

[0104] In an optional embodiment, the energy transfer device further includes a second tuning circuit including a second inductor unit and a second capacitor unit having a second ground capacitance, where the inductor unit and the capacitor unit are connected in series between ground and one of the first conductive line and the second conductive line, and the second inductor unit and the second capacitor unit are connected in series between ground and the other of the first conductive line and the second conductive line, and optionally the second inductor unit has a second tuning inductance such that the second tuning circuit and the first leakage capacitor form a resonant circuit having a resonant frequency matched to the first frequency.

[0105] A second tuning circuit may be provided to reduce leakage current caused by the same or a further electrical element but affecting the other of the first and second conductive lines. In a further embodiment, the electrical element may provide a first leakage capacitance to the first and second conductive lines. In this case, the second tuning circuit reduces or eliminates leakage current from the other of the first and second conductive lines.

[0106] The same considerations, optional embodiments, and / or properties discussed in relation to the (first) tuned circuit apply equally to the second tuned circuit.

[0107] Furthermore, two or more first and / or second tuning circuits may be provided, each of the two or more first and / or second tuning circuits configured to reduce a leakage current caused by a respective electric element. Thus, when several electric elements are present, causing several different leakage currents, an equal number of tuning circuits may be provided to reduce or minimize the respective leakage currents.

[0108] In an optional embodiment, the generator unit includes a first generator configured to generate high frequency electromagnetic energy and / or microwave electromagnetic energy having a first frequency, a second generator configured to generate high frequency electromagnetic energy and / or microwave electromagnetic energy having a second frequency different from the first frequency, and a multiplexer including a first input port, a second input port, and an output port, where the first generator is connected to the first input port, the second generator is connected to the second input port, and the energy delivery device is connected to the output port.

[0109] The first and second generators may be generators providing respective fixed frequencies or may be tunable generators configured to generate frequencies in a continuous range between a minimum frequency and a maximum frequency. The first and second frequencies may be different from each other.

[0110] The generator unit may include a generator for generating a microwave frequency and a microwave-to-RF converter. The RF frequency may be generated by coupling the microwave-to-RF converter to a microwave frequency generator, for example by using a switch. The first leakage capacitance may be changed when connecting the microwave-to-RF converter to the microwave frequency generator.

[0111] In one embodiment, the multiplexer is a diplexer. However, the present invention is not limited thereto. The generator unit may include n generators (the first to nth generators) and n input ports (the first to nth input ports) of the multiplexer, where n is an integer. The kth generator is connected to the kth input port, where k is an integer satisfying 1≦k≦n.

[0112] The output port couples the electromagnetic energy provided to each input port to the output port, thus coupling the output of each generator to the energy transfer device. The first through nth generators may operate simultaneously or alternately.

[0113] In an optional embodiment, the electrosurgical device further includes an elongate body configured to be inserted into a working channel of a surgical scoping device and including a proximal end and a distal end, the emitting device being attached to the distal end, and the first conductive wire and the second conductive wire extending within the elongate body.

[0114] The elongate body may be a cover for or may surround the first and second conductive wires. The elongate body may include a tube or hose. The first and second conductive wires may be flexible to be inserted into a working channel of a scoping device.

[0115] Also disclosed herein is a method for reducing leakage current using an energy delivery device for delivering high frequency electromagnetic energy and / or microwave electromagnetic energy, the energy delivery device including a first conductive line and a second conductive line, the method including: (i) supplying high frequency electromagnetic energy and / or microwave electromagnetic energy having a first frequency to the first conductive line and / or the second conductive line; (ii) providing a tuning circuit including an inductor unit and a capacitor unit having a ground capacitance, the inductor unit and the capacitor unit being connected in series between ground and the first conductive line and / or between ground and the second conductive line; and (iii) setting a tuning inductance of the inductor unit such that the tuning circuit and the first leakage capacitance form a parallel resonant circuit having a resonant frequency matched to the first frequency.

[0116] Any of the features of the electrosurgical devices and systems described herein may be utilized in the methods.

[0117] As used herein, the terms "proximal" and "distal" refer to the ends of a structure (e.g., an electrosurgical instrument, a coaxial feed cable, etc.) that are further from and closer to the treatment zone, respectively. Thus, during use, the proximal end of the structure is accessible by the user, while the distal end is closer to the treatment site, i.e., the patient.

[0118] The term "conductive" is used herein to mean electrically conducting, unless the context indicates otherwise.

[0119] As used below, the term "longitudinal" refers to a direction along the length of the instrument channel, parallel to the axis of the coaxial transmission line. The term "lateral" refers to a direction perpendicular to the longitudinal direction. As used herein, the term "inner" means radially closer to the center (e.g., axis) of the instrument channel. The term "outer" means radially away from the center (axis) of the instrument channel.

[0120] Embodiments of the present invention will now be described with reference to the accompanying drawings. [Brief description of the drawings]

[0121] [Figure 1] 1 is a schematic diagram of an electrosurgical device. [Diagram 2] 1 is a schematic diagram of a portion of an energy delivery device of an electrosurgical apparatus according to a first embodiment. [Diagram 3] 13 is a schematic diagram of a portion of an energy delivery device of an electrosurgical apparatus according to a second embodiment. [Figure 4] 13 is a schematic diagram of a portion of an energy delivery device of an electrosurgical apparatus according to a third embodiment. [Diagram 5] 13 is a schematic diagram of a portion of an energy delivery device of an electrosurgical apparatus according to a fourth embodiment. [Figure 6] FIG. 1 is a schematic diagram showing a setup for measuring leakage current. [Figure 7]1 is a block diagram illustrating method steps for reducing leakage current. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0122] 1 is a schematic diagram of an electrosurgical device 10 according to one embodiment of the present invention. The device 10 is configured to treat biological tissue (e.g., tumors, lesions, or fibroids) using radio frequency (RF) electromagnetic (EM) energy and / or microwave EM energy delivered from a radiating device 12. The EM energy emitted by the radiating device 12 within a treatment zone can be used to coagulate, cut, and / or ablate tissue within the treatment zone.

[0123] The electrosurgical apparatus 10 includes a generator device 11 and an emitting device 12. The generator device 11 includes a generator unit 14 for controllably supplying RF EM energy and / or microwave EM energy and an energy delivery device 16. The generator unit 14 may include one or more generators. Suitable generators for this purpose are described in WO2012 / 076844, which is incorporated herein by reference. The generator unit 11 may be configured to monitor a reflected signal received back from the emitting device 12 to determine an appropriate power level to deliver. For example, the generator unit 14 may be configured to calculate the impedance seen by the emitting device 12 to determine an optimal delivery power level.

[0124] The electrosurgical apparatus 10 further includes a surgical scoping device 18, such as a bronchoscope, endoscope, gastroscope, laparoscope, or the like. The scoping device 18 may include a handpiece 20 and a flexible shaft 22. The handpiece 20 may include means for guiding the flexible shaft 22 through a body cavity. For example, the handpiece 20 may include means for moving the distal end of the flexible shaft 22 to change the direction of the distal end of the flexible shaft 22. This helps to manipulate the flexible shaft 22 through the body cavity. The flexible shaft 22 may include a working channel, and an elongated structure may be moved through the working channel so that it can be positioned at a treatment zone within the body cavity.

[0125] The generator unit 14 may include a first generator 24 and a second generator 26, each configured to generate electromagnetic radiation at a fixed frequency. However, the generator unit 14 is not limited thereto, and the first generator 24 and / or the second generator 26 may be configured to generate AC electromagnetic energy within a continuous range between a minimum frequency and a maximum frequency. The frequency of the electromagnetic energy generated by the first generator 24 and / or the second generator 26 may be selected using an interface (not shown).

[0126] The generator unit 14 or the energy transfer device 16 may include a multiplexer 28 including a first input port 30, a second input port 32, and an output port 34. The first input port 30 is electrically coupled to the first generator 24, and the second input port 32 is electrically coupled to the second generator 26. The multiplexer 28 combines the inputs at the first input port 30 and the second input port 32 and outputs the combined inputs at the output port 34. Additionally or alternatively, the multiplexer 28 outputs the input at the first input port 30 or the input at the second input port 32 at the output port 34. In this embodiment, the first generator 24 and the second generator 26 operate alternately. That is, the first generator 24 or the second generator 26 is operating, but not simultaneously. However, it is also possible that the first generator 24 and the second generator 26 operate simultaneously. The output port 34 is electrically connected to a generator unit output 36, which is the output of the generator unit 14. In other words, the electromagnetic energy generated by the generator unit 14 is output at a generator unit output 36 that is electrically connected to the energy delivery device 16. In the embodiment shown in Figure 1, the multiplexer 28 is part of the generator unit 14. For example, the multiplexer 28 is disposed within a housing of the generator unit 14.

[0127] The energy transfer device 16 may include a transmission line 38, an isolation transformer 40, and a tuning controller 42. In the embodiment shown in Fig. 1, the isolation transformer 40 and the tuning controller 42 are part of the generator unit 14, for example located within the housing of the generator unit 14. However, the invention is not limited thereto. The isolation transformer 40 and the tuning controller 42 may be located outside the generator unit 14. In other words, parts of the energy transfer device 16 may be located together with the housing of the generator unit 14.

[0128] The transmission line 38 may include a first conductive wire 44 (see FIGS. 2-4), a second conductive wire 46 (see FIGS. 2-4), and an elongated body (not explicitly shown in the figures). The transmission line 38 is connected to the generator unit output 36, and a distal end of the transmission line 38 is connected to the radiating device 12 (not shown to scale in FIG. 1). A portion of the transmission line 38, a portion of the first conductive wire 44, and / or a portion of the second conductive wire 46 may extend within the generator unit 14. The first conductive wire 44 and the second conductive wire 46 extend from a proximal end to a distal end and are covered by the elongated body.

[0129] The transmission line 38 may include a coaxial cable and is insertable through the entire length of the working channel of the flexible shaft 22 (including the elongated body). The radiating device 12 is shaped to pass through the working channel of the flexible shaft 22 and protrude (e.g., into the patient) at a distal end of the working channel of the flexible shaft 22. The radiating device 12 includes an RF and / or microwave antenna for delivering RF and / or microwave energy to the treatment zone.

[0130] The structure of the emitting device 12 may be configured to have a maximum outer diameter suitable for passing through a working channel. Typically, the diameter of the working channel of a surgical scoping device, such as an endoscope, is less than 4.0 mm, such as, for example, any one of 2.8 mm, 3.2 mm, 3.7 mm, 3.8 mm. The length of the transmission line 38 may be 1.2 m or more, such as, for example, 2 m or more. In another example, the emitting device 12 may be attached to a distal end of the transmission line 38, which has been inserted through the working channel (prior to introducing the flexible shaft 22 into the patient).

[0131] Alternatively, the transmission line 38 can be inserted into the working channel from its distal end before making its proximal connection. In these configurations, the emitting device 12 may be permitted to have a larger dimension than the working channel of the surgical scoping device 114.

[0132] The scoping device 22 described above is one way of introducing the electrosurgical device 10. Other techniques are possible. For example, the electrosurgical device 10 may be inserted using a catheter.

[0133] The isolation transformer 40 may be disposed within the housing of the generator unit 14. The isolation transformer 40 may be electrically connected between the first generator 24 or the second generator 26 and a respective tuning controller 42, which in turn is electrically connected between the isolation transformer 40 and the multiplexer 28. The multiplexer 28 is electrically coupled to the first generator 24 and the second generator 26 via the respective tuning controller 42 and the isolation transformer 40.

[0134] A different isolation transformer 40 may be provided for each of the first generator 24 and the second generator 26. When all the individual leakage capacitances are added together, different connections of the multiplexer 28 may result in an increase or change in the leakage capacitance. The isolation transformer 40 and / or the tuning control 42 may be omitted.

[0135] The isolation transformer 40 is an example of an electrical element that provides a first leakage capacitance. In other words, the transmission line 38 and the isolation transformer 40 are electrically isolated when direct current (DC) is supplied to the isolation transformer 40 and the transmission line 38. However, when alternating current (AC) is supplied to the isolation transformer 40 and the transmission line 38 (e.g., at a frequency that is very short compared to the wavelength of the transmission line 38), the isolation transformer 40 has the electrical characteristics of a leakage capacitor 48 having a first leakage capacitance disposed between the transmission line 38 and the ground or neutral terminal. Thus, during AC operation, leakage current flows through the isolation transformer 40 (or the leakage capacitor 48) to the ground or neutral terminal. The amount of leakage current depends on the frequency of the electromagnetic energy supplied to the transmission line 38 and the isolation transformer 40. From an electrical standpoint, the leakage capacitor 48 can be connected between the first conductive wire 44 and the ground / neutral terminal and / or between the second conductive wire 46 and the ground / neutral terminal (see also Figures 2-4).

[0136] An isolation transformer 40 is provided to electrically isolate the first generator 24 and the second generator 26, respectively, from the radiating tip 12. The isolation transformer 40 may include two coils or windings that may function as or provide the properties of a leakage capacitor 48.

[0137] Tuning control device 42 may include tuning circuitry 50, a measurement device 52, a display device 54, an input device 56, and / or a control device 58. Tuning control device 42 is described in more detail in conjunction with Figures 2-4.

[0138] The transmission line 38 includes a first conductive line 44 and a second conductive line 46, each of which may be electrically coupled or connected to an isolation transformer 40 (only one coil is shown in Figs. 2-4), and the radiating device 12, represented by a resistor. The property of the isolation transformer 40 acting as or providing a first leakage capacitance is shown diagrammatically by a leakage capacitor 48 electrically connected to a coil of the isolation transformer 40. However, the isolation transformer 40 may not be the only source of leakage capacitance. For example, a microwave choke is provided to prevent leakage of microwave energy. Microwave isolation may also be provided by a separate microwave isolation transformer. The microwave choke or a separate microwave isolation transformer may act as an additional or second leakage capacitance, as shown in Figs. 2-5 as a leakage capacitor 48 connected to the second conductive line 46. This second leakage capacitor 48 may not be permanently connected to the second conductive line 46 such that only one of the two leakage capacitors 48 is connected to the second conductive line 46. This may require that the characteristics of the tuned circuit 60 need to be changed depending on which of the leakage capacitors 48 is connected to the first conductive line 46. Furthermore, the combination of leakage capacitors 48 constitutes a (first) leakage capacitance when both leakage capacitors 48 are connected to the second conductive line 46.

[0139] It should be noted that there may be further sources of leakage capacitance (providing a second leakage capacitance) essentially depending on the configuration of the transmission line 38, the isolation transformer 40, the generator unit 14, and / or other electrical components.

[0140] To reduce or eliminate leakage current, a tuning circuit 50 is provided. Due to the electrical connection of the tuning capacitor 48 in the embodiment of Figures 2-4, the tuning circuit 50 is electrically connected between the second conductive line 46 and the ground / neutral terminal. Thus, the tuning circuit 50 and the leakage capacitor 48 are connected in parallel between the second conductive line 46 and the ground / neutral terminal.

[0141] The tuned circuit 50 includes an inductor unit 60 and a capacitor unit 62 connected in series between the second conductive line 46 and the ground / neutral terminal. The inductor unit 60 includes one or more tuning inductors 64. In the embodiment of FIG. 2, the inductor unit 60 includes one tuning inductor 64. The capacitor unit 62 includes one or more capacitors 66. In the embodiment of FIG. 2, the capacitor unit 62 includes two capacitors 66. The capacitor unit 62 provides DC isolation for the tuned circuit 50. Although it would be sufficient to provide only one capacitor 66, two capacitors 66 are provided for redundancy and therefore for increased safety.

[0142] The tuning circuit 50 (particularly the inductor unit 60) and the leakage capacitor 48 form a parallel resonant circuit of an LC circuit. In the embodiment of Fig. 2, the tuning inductance of the inductor unit 60, defined by a single tuning inductor 64, is selected such that the resonant frequency of the resonant circuit is equal to or close to the frequency generated by the generator unit 14 (the frequency of the electromagnetic energy propagating through the transmission line 38). In this case, the impedance of the resonant circuit becomes very high, leading to a significant reduction or even substantial elimination of leakage currents.

[0143] It should be noted that the reduction of leakage current only benefits frequencies of electromagnetic radiation propagating in the transmission line 38 that are close to the resonant frequency of the resonant circuit. Thus, in the embodiment of Fig. 2, the generator unit 14 may include only the first generator 24 that generates a fixed frequency close to or equal to the resonant frequency of the resonant circuit. In this case, the measuring device 52, the display device 54, the input device 56, and / or the control device 58 may be omitted.

[0144] The capacitance of the capacitor unit 62 may be selected to be an order of magnitude larger than the first leakage capacitance of the leakage capacitor 48. In this case, the capacitor unit 62 does not substantially interact with the electromagnetic energy propagating in the transmission line 38. In other words, the capacitor unit 62 does not substantially affect the resonant frequency of the tuned circuit 50 and / or the resonant circuit. The capacitor unit 62 is provided for DC isolation.

[0145] The leakage current may be measured as the current flowing through a 200 Ω test resistor 68. The test resistor 68 may be connected to the transmission line 38 for the sole purpose of measuring or controlling the leakage current.

[0146] In one example, at 400 kHz, with a 1 kΩ load of the radiating device 12, the first total leakage capacitance of one of the first conductive line 44 or the second conductive line 46 that would keep the power in the 200 Ω test resistor 68 of the opposing line below the allowable limit would be approximately 80 pF. The isolation transformer 40 and associated circuitry may have a capacitance of 60 pF. This contributes approximately 30 pF to each line of the first conductive line 44 or the second conductive line 46, so that the allowable additional capacitance to ground is 50 pF. For operation at 400 kHz, the capacitance of the capacitor unit 62 of approximately 1 μF in series with the inductance of the inductor unit 60 of approximately 1 mH would be adequate to offset the first leakage capacitance of the leakage capacitor 48 of approximately 100 pF.

[0147] In the embodiment shown in FIG. 3, the tuning circuit 50 further includes a switch unit 70 to switch the tuning inductance of the inductor unit 60 between two inductances. The inductor unit 60 includes two tuning inductors 64, one of which is permanently connected in series with the capacitor unit 62, and the other tuning inductor 64 is connected to the capacitor unit 62 only when the switch unit 70 is in a closed state. In other words, in the open state of the switch unit 70, the tuning inductance of the inductor unit 60 is determined by the tuning inductor 64 permanently connected in series with the capacitance unit 62. In the closed state of the switch unit 70, the tuning inductance of the inductor unit 60 is determined by both tuning inductors 64. Thus, the inductor unit 60 has two fixed tuning inductances that can be selected by operating the switch unit 70.

[0148] This provides two resonant frequencies of the resonant circuit so as to reduce leakage currents at two frequencies of the electromagnetic energy propagating in the transmission line 38. The embodiment of Fig. 3 may be used when the generator unit 14 includes a first generator 24 and a second generator 26, each generating a fixed frequency. In this case, the inductance of the tuning inductor 64 is selected such that the resonant frequencies of the resonant circuits (in the open and closed states of the switch unit 70) are close to or equal to the frequencies generated by the first generator 24 (e.g., first frequency) and the second generator 26 (e.g., second frequency), respectively.

[0149] Furthermore, the switch unit 70 provides a reduction or cancellation of leakage currents caused by different leakage capacitances (and thus different resonant circuits of the resonant circuits). Thus, the switch unit 70 allows for reduction in leakage current cancellation or different tuning inductances for different tools (such as radiating devices) and different connected generators that may have different leakage capacitances and require different tuning inductances to cancel them at the same frequency.

[0150] The inductor unit 60 may also include one or more tuning capacitors (not shown in FIG. 3) that may be used to fine-tune the resonant frequency of the resonant circuit. Furthermore, these one or more tuning capacitors may be switchable into the inductor unit 60 by the switch unit 70.

[0151] If the generator unit 14 is configured to generate more than two fixed frequencies (e.g., by including more than two generators), the tuning circuit 50 may include further switches or switch units 70 and the inductor unit 60 includes further tuning inductors 64 and / or tuning capacitors to provide three or more different resonant frequencies of the resonant circuit. This makes it possible to reduce or eliminate leakage currents at each of the frequencies generated by the generator unit 14 and / or caused by different leakage capacitances caused by different electrical components connected to the energy delivery device 16. In this embodiment, the measuring device 52, the display device 54, the input device 56, and / or the control device 58 may be omitted.

[0152] In the embodiment shown in Fig. 4, the inductance of the inductor unit 60 is tunable or changeable. This may be provided by a tunable tuning inductor 64, the inductance of which can be changed / varied. Alternatively or additionally, the resonant frequency of the resonant circuit may be tunable by providing a tunable capacitor (whose capacitance can be changed / varied) with the inductor unit 60. The inductance of the tunable tuning inductor 64 may be tuned / varied / changed to a value such that the resonant frequency of the resonant circuit is equal to or close to the frequency generated by the generator unit 14.

[0153] This may be done manually. For this purpose, a measuring device 52 may be provided that is configured to measure the amount of leakage current. Any known means for measuring the leakage current may be implemented by the measuring device 52. The measuring device 52 may be electrically and / or electronically connected to a display device 54, which may include a screen or a display. The display device 54 may be configured to display the leakage current measured by the measuring device 52. A user of the electrosurgical apparatus 10 may use the input device 56 to vary the inductance of the inductor unit 60 and / or to vary the resonant frequency of the resonant circuit (in the case of a tunable tunable capacitor). The input device 56 may be a mechanical or electrical means for varying the inductance of the inductor unit 60 and / or the capacitance of the inductor unit 60. For example, the user manipulates the input device 56 in such a way that the leakage current is reduced.

[0154] The tuning of the inductor unit 60 may be performed automatically. For this purpose, a control device 58 may be provided, which is connected to the measuring device 52 and / or the input device 56. The control device 58 may be a computer or the like capable of receiving the value of the leakage current from the measuring device 52 and controls the operation of the input device 56 in order to reduce the leakage current or directly controls the tuning inductor and / or the tunable tuning capacitor.

[0155] It should be noted that different combinations of features from the embodiments shown in Figures 2-4 are possible and the embodiments shown in Figures 2-4 are shown by way of example only. For example, the tuning circuit 50 may include both the switch unit 70 and the tunable tuning inductor 64.

[0156] Additionally, if desired, a separate tuning circuit 50 can be used for each of the first and second conductive lines 44, 46. The separate tuning circuits 50 can have the same characteristics as the tuning circuits 50 shown in Figures 2-4.

[0157] In the embodiment shown in Fig. 5, an additional capacitor unit 72 is provided between ground and the second conductive line 46. The additional capacitor unit 72 is tunable, meaning that the additional capacitance of the additional capacitor unit 72 is variable. A change in the additional capacitance changes the resonant frequency of the resonant circuit, similar to the tunable inductor unit 60 described in relation to Fig. 4. The difference is that the tunable inductor unit 60 changes the inductance of the resonant circuit, whereas the additional capacitor unit 72 changes the capacitance of the resonant circuit. However, both changes result in a change in the resonant frequency.

[0158] The additional capacitor unit 72 may include a tunable additional capacitor 74 and / or a redundant additional capacitor 76. The tunable additional capacitor 74 provides a tunable characteristic of the additional capacitor unit 72. The redundant additional capacitor 76 is provided for redundancy reasons, i.e. in the case of the tunable additional capacitor 74, the redundant additional capacitor 76 provides DC isolation for the additional capacitor unit 72.

[0159] In a further embodiment not shown in the figures, the capacitor unit 62 may have the properties of the additional capacitor unit 72. Thus, in this embodiment, one of the capacitors 66 may be tunable or variable. For example, one of the capacitors 66 may be replaced by a tunable additional capacitor 74. The ground capacitance is thus variable such that the capacitor unit 62 may also contribute to the tuning of the tuning circuit 50.

[0160] Figure 6 shows the setup for measuring leakage current. The electrosurgical device 10 may be isolated from the ground wire and from other applied parts at both high and low frequencies. The leakage current flowing from either pole of the bipolar output through a 200 Ω non-inductive resistor on each line to the ground wire and to the neutral electrode must not exceed a value that produces a power equal to 1% of the maximum bipolar rated output power at the 200 Ω non-inductive test resistor 68, with all output controls set to maximum. This compliance can be verified by the following test.

[0161] The electrosurgical device 10 is set up as shown in FIG. 6. Testing is performed using one side of the bipolar output, as well as the bipolar lead and neutral electrode lead (if applicable). Testing is performed with the output first unloaded, and then repeated with the output loaded at rated load. The squared current value multiplied by the 200 Ω test resistor 68 must not exceed the above requirements. The testing is then repeated for the other side of the bipolar output.

[0162] The keys in FIG. 6 are: 1: supply main, 2: table made of insulating material, 3: electrosurgical device 10, 5: neutral electrode, metal or in contact with metal foil of the same size, 7: test resistance 200 Ω, 8: measuring device 52 (high frequency ammeter), 9: grounded conductive surface, 10: activated bipolar accessory (e.g. radiating device 12).

[0163] A method for reducing leakage current using the energy delivery device 16 is described in relation to Figure 7. The first step is to supply high frequency and / or microwave electromagnetic energy to the first conductive line 44 and / or the second conductive line 46. This may be done by using the generator unit 14 as described above.

[0164] In a second step, a tuning circuit 50 is provided, as illustrated in Figures 2 to 5. In a third step, the tuning inductance of the tuning circuit 50 is set such that the tuning circuit 50 and the leakage capacitor 48 form a parallel resonant circuit having a resonant frequency equal to or close to the frequency generated by the generator unit 14. This setting step may be performed as described in connection with Figures 2-5.

[0165] It should be noted that the first to third steps may not be performed in the order described above, for example the second step may be the first step performed.

Claims

1. 1. An energy delivery device for delivering radio frequency and / or microwave electromagnetic energy, comprising: first and second conductive wires configured to transmit high frequency and / or microwave electromagnetic energy having a first frequency; an electrical element providing a first leakage capacitance, the first leakage capacitance being between the first conductive line and ground and / or between the second conductive line and ground; a tuning circuit including an inductor unit and a capacitor unit having a capacitance to ground, the inductor unit and the capacitor unit being connected in series between the ground and either the first conductive line or the second conductive line; the inductor unit has a tuning inductance such that the tuning circuit and the first leakage capacitance form a resonant circuit having a resonant frequency matched to the first frequency; The energy transfer device further includes an additional capacitor unit having an additional capacitance that is variable, the additional capacitor unit being connected in series between the ground and either the first conductive line or the second conductive line.

2. 10. The energy transfer device of claim 1, wherein the capacitance to ground of the capacitor unit is optionally at least 10, 100, or 1000 times greater than the first leakage capacitance.

3. 3. The energy transfer device of claim 1, wherein the inductor unit comprises one tuning inductor having the tuning inductance or two or more tuning inductors permanently connected to each other that together provide the tuning inductance.

4. The inductor unit is 3. The energy transfer device of claim 1, comprising two or more tuning inductors and a switch unit, the switch unit configured to selectively electrically connect one or more tuning inductors to the capacitor unit to selectively vary the tuning inductance of the tuning circuit.

5. The inductor unit is 3. The energy transfer device of claim 1, comprising at least one tuning inductor, at least one tuning capacitor, and a switch unit configured to selectively electrically connect one or more tuning inductors and / or one or more tuning capacitors to selectively vary the resonant frequency of the resonant circuit.

6. the first conductive line and the second conductive line are configured to transmit high frequency electromagnetic energy and / or microwave electromagnetic energy having a second frequency different from the first frequency; and / or the electrical element provides a second leakage capacitance different from the first leakage capacitance; the tuning circuit is configured to selectively vary the resonant frequency of the resonant circuit such that the resonant frequency is matched to the first frequency or the second frequency; and / or 5. The energy transfer device of claim 4, wherein the tuning circuit is configured to selectively vary the resonant circuit such that the tuning circuit and the first or second leakage capacitance form a resonant circuit having a respective resonant frequency matched to the first frequency.

7. 3. An energy transfer device according to claim 1 or 2, wherein the inductor unit comprises at least one tuning inductor and / or at least one tuning capacitor that is variable to vary the resonant frequency of the resonant circuit.

8. the first conductive line and the second conductive line are configured to transmit the radio frequency electromagnetic energy and / or microwave electromagnetic energy having a second frequency different from the first frequency; and / or the electrical element provides a second leakage capacitance different from the first leakage capacitance; the tuning circuit is configured to be altered to selectively change the resonant frequency of the resonant circuit so that the resonant frequency is matched to the first frequency or the second frequency; and / or 8. The energy transfer device of claim 7, wherein the tuning circuit is configured to selectively vary the tuning circuit such that the tuning circuit and the first or second leakage capacitance form a resonant circuit having a respective resonant frequency matched to the first frequency.

9. the first conductive line and the second conductive line are configured to transmit the radio frequency electromagnetic energy and / or microwave electromagnetic energy having a second frequency different from the first frequency; and / or the electrical element provides a second leakage capacitance different from the first leakage capacitance; the additional capacitor unit is configured to be varied to selectively change the resonant frequency of the resonant circuit so that the resonant frequency is matched to the first frequency or the second frequency; and / or 2. The energy transfer device of claim 1, wherein the additional capacitor unit is configured to selectively vary the tuning circuit such that the tuning circuit and the first or second leakage capacitance form a resonant circuit having a respective resonant frequency matched to the first frequency.

10. 10. The energy transfer device of claim 1, further comprising a measurement device for measuring and / or monitoring leakage current induced by the first leakage capacitance.

11. a display device for displaying the leakage current measured by the measuring device; 11. The energy transfer device of claim 10, further comprising: an input device for varying the resonant frequency of the resonant circuit by modifying the at least one tuning inductor and / or the at least one tuning capacitor.

12. 12. The energy transfer device of claim 10 or 11, further comprising a control device configured to modify the at least one tuning inductor, the additional capacitor unit, and / or the at least one tuning capacitor to change the resonant frequency of the resonant circuit based on the leakage current measured by the measuring device.

13. The energy transfer device of claim 1 , wherein the capacitor unit comprises two or more capacitors, optionally connected in series with each other.

14. a second tuning circuit including a second inductor unit and a second capacitor unit having a second capacitance to ground, wherein the inductor unit and the capacitor unit are connected in series between the ground and either the first conductive line or the second conductive line, and the second inductor unit and the second capacitor unit are connected in series between the ground and the other of the first conductive line and the second conductive line; 2. The energy transfer device of claim 1, wherein the second inductor unit has a second tuning inductance such that the second tuning circuit and the first leakage capacitance form a resonant circuit having a second resonant frequency matched to the first frequency.

15. The energy transfer device of claim 1 , wherein the electrical element comprises an isolation transformer, a microwave choke, and / or a multiplexer.

16. 1. A generator device for generating and / or transmitting radio frequency and / or microwave electromagnetic energy, comprising: a generator unit configured to generate high frequency electromagnetic energy and / or microwave electromagnetic energy having the first frequency; 2. The energy-transmission device of claim 1, comprising: the energy-transmission device electrically coupled to the generator unit to receive the high-frequency electromagnetic energy and / or microwave electromagnetic energy having the first frequency.

17. The generator unit is a first generator configured to generate radio frequency electromagnetic energy and / or microwave electromagnetic energy having the first frequency; a second generator configured to generate high frequency and / or microwave electromagnetic energy having a second frequency, the second frequency being different from the first frequency; and a multiplexer including a first input port, a second input port, and an output port; 17. The generator device of claim 16, wherein the first generator is coupled to the first input port, the second generator is coupled to the second input port, and the energy delivery device is coupled to the output port.

18. 1. An electrosurgical device comprising: The generator device according to claim 16 or 17; and a radiation device for emitting high frequency electromagnetic energy and / or microwave electromagnetic energy.

19. an elongate body configured to be inserted into a working channel of a surgical scoping device, the elongate body including a proximal end and a distal end; a radiation device attached to the distal end; The electrosurgical device of claim 18 , wherein the first and second conductive wires extend within the elongate body.

20. 1. A method for reducing leakage current using an energy delivery device for delivering radio frequency and / or microwave electromagnetic energy, the energy delivery device comprising a first conductive wire and a second conductive wire, the method comprising: applying high frequency electromagnetic energy and / or microwave electromagnetic energy having a first frequency to the first conductive line and / or the second conductive line; providing a tuning circuit including an inductor unit and a capacitor unit having a capacitance to ground, wherein the inductor unit and the capacitor unit are connected in series between ground and the first conductive line and / or between the ground and the second conductive line; providing an additional capacitor unit having a variable additional capacitance, the additional capacitor unit being connected in series between the ground and either the first conductive line or the second conductive line; setting a tuning inductance of the inductor unit so that the tuning circuit and a first leakage capacitance form a parallel resonant circuit having a resonant frequency matched to the first frequency.

Images