A capacitive coupled three-electrode plasma scalpel for low conductivity scenarios

Abstract

This invention provides a capacitively coupled three-electrode plasma scalpel for use in low-conductivity scenarios, comprising a three-electrode scalpel and a power supply unit providing power to the scalpel. The three-electrode scalpel includes a pulse excitation electrode, a radio frequency sustaining electrode, a grounding electrode, and a current probe; the power supply unit includes an EMI filtering module, a PFC power correction module, an LLC resonant converter module, a full-bridge rectifier module, a pulse generation module, a radio frequency generation module, a capacitive coupling module, and an FPGA control module. This invention excites plasma using bipolar high-voltage pulses, and after the plasma stabilizes, switches to high-frequency sinusoidal radio frequency energy to maintain its ionization state. Capacitive coupling technology is used to achieve efficient energy transfer to the three surgical electrodes, solving the technical problems of difficult plasma excitation, unstable maintenance, easy arc breakage, and thermal damage to tissues in low-conductivity scenarios.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and more particularly to a capacitively coupled three-electrode plasma scalpel for use in low conductivity scenarios. Background Technology

[0002] In the process of activating plasma in a plasma scalpel, bubbles are first formed in saline solution through Joule heating, then accumulate into a vapor layer that surrounds the electrodes. Applying voltage further breaks down this vapor layer, thus forming a plasma tunnel. Current plasma scalpel power outputs are divided into radio frequency output and pulse output.

[0003] Radio frequency output plasma scalpels form a vapor layer slowly during the plasma generation phase, leading to unstable excitation and thermal damage to tissues before plasma formation. Pulsed output plasma scalpels require periodic power supply during the plasma maintenance phase, waiting for the next pulse cycle, which causes plasma fluctuations and arc breakage issues during the intermediate time. Single waveform excitation and maintenance can cause a rapid drop in impedance and an increase in current during the excitation plasma, affecting tissues.

[0004] Currently, most surgical scalpels and power outputs are directly connected to a single power supply and a single or dual electrode scalpel head. However, the secondary electron emission coefficient of metal electrodes is much larger than that of saline solution, resulting in more intense negative voltage discharge than positive voltage discharge. This can easily generate DC and low-frequency leakage current that directly reaches the patient and causes nerve stimulation. Furthermore, DC can easily affect the electrodes.

[0005] When conventional plasma scalpels are used to treat low-conductivity scenarios such as stones, the stones (such as calcium oxalate and calcium carbonate stones) can capture sodium and chloride ions in saline solution through surface adsorption and weak ion exchange. Furthermore, the saline solution rinsing during surgery accelerates the mixing of low-conductivity tissue exudate and increases the contact area between stone debris and saline solution, further consuming effective conductive ions. This leads to a significant decrease in the conductivity of the saline solution, making it difficult for conventional power systems to overcome the resistance threshold of low-conductivity media. Consequently, it is impossible to quickly and stably generate a vapor layer to form plasma, or to maintain the continuous action of the plasma. Summary of the Invention

[0006] To address the technical problems of existing technologies, such as unstable plasma excitation, easy arc interruption during the maintenance phase, thermal damage to tissues, and difficulty in exciting and maintaining plasma in low-conductivity environments, this invention provides a capacitively coupled three-electrode plasma surgical scalpel for use in low-conductivity environments. This invention primarily utilizes a dual-mode synergistic mechanism of bipolar high-voltage pulse excitation and high-frequency sinusoidal radio frequency maintenance, combined with capacitive coupling energy transfer technology and FPGA real-time control technology, thereby achieving the technical effects of rapidly and stably exciting and maintaining plasma in low-conductivity media, avoiding tissue thermal damage, and eliminating the stimulation of the human body by DC leakage current.

[0007] The technical means employed in this invention are as follows: A capacitively coupled three-electrode plasma scalpel for use in low-conductivity scenarios includes a three-electrode scalpel and a power supply unit that provides power to the three-electrode scalpel, wherein: The three-electrode surgical knife includes a pulse excitation electrode, a radio frequency sustaining electrode, a ground electrode, and a current probe; the power supply unit includes an EMI filtering module, a PFC power correction module, an LLC resonant converter module, a full-bridge rectifier module, a pulse generation module, a radio frequency generation module, a capacitive coupling module, and an FPGA control module, wherein: The pulse generation module is used to generate bipolar high-voltage pulses, which are transmitted to the pulse excitation electrode via a capacitive coupling module to excite plasma in a low-conductivity medium. The radio frequency generation module is used to generate high-frequency sinusoidal radio frequency energy, which is transmitted to the radio frequency sustaining electrode via the capacitive coupling module to sustain the formed plasma. The FPGA control module is used to receive the current signal detected by the current probe and control the switching between the pulse generation module and the radio frequency generation module according to the current change characteristics. The capacitive coupling module is used to transmit the energy output from the pulse generation module and the radio frequency generation module to the three-electrode scalpel and to block the DC component.

[0008] The connection relationships are as follows: The input of the EMI filter module is connected to a 220V AC mains power supply, and its output is connected to the input of the PFC power correction module. The output of the PFC power correction module is connected to the input of the LLC resonant converter module. The output of the LLC resonant converter module is connected to the input of the full-bridge rectifier module. The output of the full-bridge rectifier module is connected to the inputs of both the pulse generation module and the RF generation module. The outputs of both the pulse generation module and the RF generation module are connected to the input of the capacitive coupling module. The output of the capacitive coupling module is connected to both the pulse excitation electrode and the RF sustaining electrode. The current probe is connected to the signal input of the FPGA control module. The signal output of the FPGA control module is connected to the control terminals of both the pulse generation module and the RF generation module. The grounding electrode has a tube wall structure.

[0009] Furthermore, the capacitive coupling module includes a pulse coupling branch and a radio frequency coupling branch; the input terminal of the pulse coupling branch is connected to the output terminal of the pulse generation module, and the output terminal is connected to the pulse excitation electrode; the input terminal of the radio frequency coupling branch is connected to the output terminal of the radio frequency generation module, and the output terminal is connected to the radio frequency sustaining electrode.

[0010] Furthermore, the pulse coupling branch includes a first The impedance matching network, the first coupling capacitor, and the first switching device IGBT connected in reverse series, wherein: The first A type of impedance matching network is used to coordinate the pulse generation module and the RF generation module to transmit pulse energy at maximum power. The first coupling capacitor is used to transmit the bipolar high voltage pulse to the scalpel electrode and block the DC component to make the positive and negative periodic discharge more balanced, and to convert the current asymmetry caused by the difference in the secondary electron emission coefficient into voltage asymmetry, thereby increasing the positive voltage and decreasing the negative voltage to achieve charge balance. The first switching device, IGBT, is used to isolate the bipolar pulse signal output by the radio frequency generation module; The connection relationships are as follows: The first The input terminal of the impedance matching network is connected to the output terminal of the pulse generation module, and the output terminal is connected to the pulse excitation electrode through the first coupling capacitor; the first IGBT, which is connected in reverse series, is connected in parallel to the first... The output of the impedance matching network is connected to the first coupling capacitor.

[0011] Furthermore, the radio frequency coupling branch includes a second The impedance matching network, the second coupling capacitor, and the second switching device MOSFET connected in reverse series, wherein: The second A type of impedance matching network is used to coordinate the pulse generation module and the RF generation module to maximize the power transmission of RF energy. The second coupling capacitor is used to transmit high-frequency sinusoidal radio frequency energy to the scalpel electrode and block the DC component to make the positive and negative periodic discharge more balanced. It converts the current asymmetry caused by the difference in the secondary electron emission coefficient into voltage asymmetry, thereby increasing the positive voltage and decreasing the negative voltage to achieve charge balance. The second switching device, a MOSFET, is used to isolate the high-frequency sinusoidal radio frequency signal output by the pulse generation module; The connection relationships are as follows: The second The input terminal of the impedance matching network is connected to the output terminal of the RF generation module, and the output terminal is connected to the RF sustain electrode through a second coupling capacitor; the second switching device MOS transistor, which is connected in reverse series, is connected in parallel to the second... The output of the impedance matching network is connected to the second coupling capacitor.

[0012] Furthermore, the pulse generation module employs a bipolar Marx generator circuit, generating a bipolar pulse with an average voltage of zero within its cycle.

[0013] Furthermore, the RF generation module includes a full-bridge inverter circuit, a filter capacitor, and an RF transformer; the input terminal of the full-bridge inverter circuit is connected to the output terminal of the full-bridge rectifier module, and the output terminal is filtered by the filter capacitor and then transformed by the RF transformer to output a high-frequency sine wave.

[0014] Furthermore, the FPGA control module determines the formation of a vapor layer based on the change in current from high to low detected by the current probe, and determines plasma breakdown based on the change in current from low to high. When plasma breakdown is detected, the pulse generation module is turned off and the radio frequency generation module is started.

[0015] Furthermore, the EMI filtering module consists of a common-mode capacitor, a differential-mode capacitor, and a common-mode inductor, and is used to filter out common-mode and differential-mode interference signals in the power grid.

[0016] Furthermore, the PFC power correction module includes a full-bridge rectifier circuit and a boost circuit, and achieves power factor optimization through MOSFETs.

[0017] Furthermore, the LLC resonant converter module consists of a full-bridge inverter circuit, an LLC resonant network, and a transformer, and achieves energy conversion and wide voltage load output through soft switching.

[0018] Compared with the prior art, the present invention has the following advantages: 1. The capacitively coupled three-electrode plasma scalpel provided by this invention for use in low conductivity scenarios generates bipolar high-voltage pulses to excite plasma through a pulse generation module, and generates high-frequency sinusoidal radio frequency energy to maintain plasma through a radio frequency generation module. Through coordinated control with an FPGA control module, rapid and stable excitation and continuous maintenance of plasma are achieved, avoiding tissue thermal damage and arc interruption problems caused by single waveform excitation and maintenance.

[0019] 2. This invention achieves energy transmission through a capacitive coupling module. By using a coupling capacitor to block the DC component, the current asymmetry caused by the difference in secondary electron emission coefficients is converted into voltage asymmetry, thereby increasing the positive voltage and decreasing the negative voltage to achieve charge balance. This effectively avoids the nerve stimulation of the human body caused by DC and low-frequency leakage current, as well as the corrosion and loss of electrodes caused by DC.

[0020] 3. This invention uses bipolar pulse excitation, which has a smaller breakdown voltage compared to unipolar pulse and radio frequency signals, and the average voltage within the cycle is zero. It can quickly break through the resistance threshold in low conductivity media to form a vapor layer and excite plasma, making it particularly suitable for low conductivity surgical scenarios such as stone removal.

[0021] 4. This invention uses a three-electrode structure design to separate the pulse excitation electrode from the radio frequency sustaining electrode, and with the help of an independent coupling branch, it achieves physical and electrical isolation between the excitation and sustaining functions, thereby improving the stability and reliability of the system.

[0022] In summary, the technical solution of this invention solves the problems of plasma scalpels in the prior art, such as difficulty in excitation, unstable maintenance, easy arc breakage, thermal damage to tissue, and the risk of DC leakage current in low conductivity scenarios. Therefore, the technical solution of this invention solves the problems of unstable plasma excitation, easy arc breakage during the maintenance phase, thermal damage to tissue, and difficulty in excitation and maintenance of plasma in low conductivity scenarios in the prior art. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a system structure diagram of the surgical knife of the present invention.

[0025] Figure 2 This is a system flowchart of the present invention.

[0026] Figure 3This is a topology diagram of the power supply unit of the present invention.

[0027] Figure 4 This is a partial structural diagram of the three-electrode plasma surgical tip of the present invention.

[0028] Figure 5 This is a partial structural schematic diagram of the three-electrode plasma surgical tip of the present invention from another perspective.

[0029] In the diagram: 1. 220V / 50Hz AC mains power; 2. EMI filter module; 3. PFC power correction module; 4. LLC resonant converter module; 5. Full-bridge rectifier module; 6. Pulse generation module; 7. RF generation module; 8. Capacitive coupling module; 9. Pulse excitation electrode; 10. RF sustaining electrode; 11. Ground electrode; 12. FPGA control module. Detailed Implementation

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0033] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0034] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0035] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0036] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0037] like Figure 1As shown, this invention provides a capacitively coupled three-electrode plasma scalpel for use in low-conductivity scenarios, comprising a three-electrode scalpel and a power supply unit that provides power to the three-electrode scalpel, wherein: The three-electrode surgical knife includes a pulse excitation electrode 9, a radio frequency sustaining electrode 10, a ground electrode 11, and a current probe; the power supply unit includes an EMI filter module 2, a PFC power correction module 3, an LLC resonant converter module 4, a full-bridge rectifier module 5, a pulse generation module 6, a radio frequency generation module 7, a capacitive coupling module 8, and an FPGA control module 12, wherein: The pulse generation module 6 is used to generate bipolar high-voltage pulses, which are transmitted to the pulse excitation electrode 9 via the capacitive coupling module 8 to excite and form plasma in a low-conductivity medium. The radio frequency generation module 7 is used to generate high-frequency sinusoidal radio frequency energy, which is transmitted to the radio frequency sustaining electrode 10 via the capacitive coupling module 8 to sustain the formed plasma. The FPGA control module 12 is used to receive the current signal detected by the current probe and control the switching between the pulse generation module 6 and the radio frequency generation module 7 according to the current change characteristics. The capacitive coupling module 8 is used to transmit the energy output from the pulse generation module 6 and the radio frequency generation module 7 to the three-electrode scalpel and to block the DC component.

[0038] The connection relationships are as follows: The input terminal of the EMI filter module 2 is connected to the 220V AC mains power 1, and the output terminal is connected to the input terminal of the PFC power correction module 3; the output terminal of the PFC power correction module 3 is connected to the input terminal of the LLC resonant converter module 4; the output terminal of the LLC resonant converter module 4 is connected to the input terminal of the full-bridge rectifier module 5; the output terminal of the full-bridge rectifier module 5 is connected to the input terminals of the pulse generation module 6 and the RF generation module 7, respectively; the output terminals of the pulse generation module 6 and the RF generation module 7 are both connected to the input terminal of the capacitive coupling module 8; the output terminal of the capacitive coupling module 8 is connected to the pulse excitation electrode 9 and the RF sustaining electrode 10, respectively; the current probe is connected to the signal input terminal of the FPGA control module 12; the signal output terminal of the FPGA control module 12 is connected to the control terminal of the pulse generation module 6 and the control terminal of the RF generation module 7, respectively; the grounding electrode 11 has a tube wall structure.

[0039] In a specific implementation, as a preferred embodiment of the present invention, the capacitive coupling module 8 includes a pulse coupling branch and a radio frequency coupling branch; the input end of the pulse coupling branch is connected to the output end of the pulse generation module 6, and the output end is connected to the pulse excitation electrode 9; the input end of the radio frequency coupling branch is connected to the output end of the radio frequency generation module 7, and the output end is connected to the radio frequency sustaining electrode 10.

[0040] In a specific implementation, as a preferred embodiment of the present invention, the pulse coupling branch includes a first The impedance matching network, the first coupling capacitor, and the first switching device IGBT connected in reverse series, wherein: The first A type of impedance matching network is used to coordinate the pulse generation module 6 and the RF generation module 7 to transmit pulse energy at maximum power. The first coupling capacitor is used to transmit the bipolar high voltage pulse to the scalpel electrode and block the DC component to make the positive and negative periodic discharge more balanced, and to convert the current asymmetry caused by the difference in the secondary electron emission coefficient into voltage asymmetry, thereby increasing the positive voltage and decreasing the negative voltage to achieve charge balance. The first switching device, IGBT, is used to isolate the bipolar pulse signal output by the radio frequency generation module 7; The connection relationships are as follows: The first The input terminal of the impedance matching network is connected to the output terminal of the pulse generation module 6, and the output terminal is connected to the pulse excitation electrode 9 through the first coupling capacitor; the first switching device IGBT, which is connected in reverse series, is connected in parallel to the first The output of the impedance matching network is connected to the first coupling capacitor.

[0041] In a specific implementation, as a preferred embodiment of the present invention, the radio frequency coupling branch includes a second The impedance matching network, the second coupling capacitor, and the second switching device MOSFET connected in reverse series, wherein: The second A type of impedance matching network is used to coordinate the pulse generation module 6 and the RF generation module 7 to maximize the power transmission of RF energy. The second coupling capacitor is used to transmit high-frequency sinusoidal radio frequency energy to the scalpel electrode and block the DC component to make the positive and negative periodic discharge more balanced. It converts the current asymmetry caused by the difference in the secondary electron emission coefficient into voltage asymmetry, thereby increasing the positive voltage and decreasing the negative voltage to achieve charge balance. The second switching device, a MOSFET, is used to isolate the high-frequency sinusoidal radio frequency signal output by the pulse generation module 6. The connection relationships are as follows: The second The input terminal of the impedance matching network is connected to the output terminal of the RF generation module 7, and the output terminal is connected to the RF sustaining electrode 10 through the second coupling capacitor; the second switching device MOS transistor, which is connected in reverse series, is connected in parallel to the second The output of the impedance matching network is connected to the second coupling capacitor.

[0042] In a specific implementation, as a preferred embodiment of the present invention, the pulse generation module 6 adopts a bipolar Marx generator circuit, and the average voltage during the bipolar pulse period is zero.

[0043] In a specific implementation, as a preferred embodiment of the present invention, the radio frequency generation module 7 includes a full-bridge inverter circuit, a filter capacitor, and a radio frequency transformer; the input terminal of the full-bridge inverter circuit is connected to the output terminal of the full-bridge rectifier module, and the output terminal is filtered by the filter capacitor and then transformed by the radio frequency transformer to output a high-frequency sine wave.

[0044] In a specific implementation, as a preferred embodiment of the present invention, the FPGA control module 12 determines the formation of a vapor layer based on the change in current from high to low detected by the current probe, determines plasma breakdown based on the change in current from low to high, and shuts down the pulse generation module 6 and starts the radio frequency generation module 7 when plasma breakdown is detected.

[0045] In a specific implementation, as a preferred embodiment of the present invention, the EMI filtering module 2 consists of a common-mode capacitor, a differential-mode capacitor, and a common-mode inductor, and is used to filter out common-mode and differential-mode interference signals in the power grid.

[0046] In a specific implementation, as a preferred embodiment of the present invention, the PFC power correction module 3 includes a full-bridge rectifier circuit and a boost circuit, and achieves power factor optimization through MOSFETs.

[0047] In a specific implementation, as a preferred embodiment of the present invention, the LLC resonant converter module 4 consists of a full-bridge inverter circuit, an LLC resonant network, and a transformer, and achieves energy conversion and wide voltage load output through soft switching.

[0048] Example In this embodiment, as Figure 2As shown, when the system is working, it first enters the initialization phase. After the system is powered on, the FPGA control module 12 starts the self-test program, sequentially checking the power supply voltage of each module, the status of the switching devices, and the signal acquisition function of the current probe. After the self-test passes, the PFC power correction module 3 and the DC-DC isolation converter (including the LLC resonant converter module 4 and the full-bridge rectifier module 5) start working, outputting a stable DC voltage, and the system enters the standby state. When the start signal is received, the system enters the pulse excitation phase. The FPGA control module 12 controls the pulse generation module 6 to work, and the generated bipolar pulse is transmitted to the pulse excitation electrode 9 and the ground electrode 11 through the pulse coupling branch. During this process, under the influence of a strong electric field at the electrode tip, physiological saline first generates tiny bubbles. As the pulse is continuously applied, the bubbles gradually gather to form a vapor layer. At this time, the current probe detects a decreasing current trend. If the pulse is continued to be applied, the vapor layer is broken down to form a plasma tunnel. The current probe detects a sudden increase in current. After the FPGA control module 12 captures the current change signal, it immediately shuts down the pulse generation module 6 and starts the radio frequency generation module 7. The system switches to the radio frequency sustaining stage. The high-frequency sine wave generated by the radio frequency generation module 7 is transmitted through the radio frequency coupling branch to the radio frequency sustaining electrode 10 and the ground electrode 11, continuously providing energy to the plasma and maintaining its stable state.

[0049] This embodiment solves the problems of delayed excitation, unstable maintenance, and electrode wear in traditional plasma scalpels through modular collaborative design. Figure 3As shown, the entire system uses 220V / 50Hz AC mains power 1 as input. First, the EMI filter module 2 filters out common-mode and differential-mode interference signals from the power grid, ensuring that subsequent modules are not affected by electromagnetic interference. Then, the PFC power correction module 3 optimizes the power factor, improves the energy utilization efficiency, and provides a stable DC input for subsequent circuits. Next, the DC-DC isolation converter composed of LLC resonant converter module 4 and full-bridge rectifier module 5 realizes electrical isolation and voltage regulation, and outputs a DC voltage adapted to the operation of pulse generation module 6 and RF generation module 7. Among them, LLC resonant converter module 4 improves energy conversion efficiency through soft switching technology, while full-bridge rectifier module 5 further optimizes the stability of the output voltage and reduces the ripple coefficient. In the core functional modules, the pulse generation module 6 employs a bipolar Marx generator circuit, capable of generating bipolar pulses that meet the requirements for rapid plasma excitation. Compared to unipolar pulses and radio frequency signals, this pulse has a lower breakdown voltage and an average voltage of zero within its cycle, effectively avoiding stimulation of the human body and damage to the electrodes caused by DC and low-frequency leakage currents. The radio frequency generation module 7 generates a high-frequency sine wave through a full-bridge inverter, filtering capacitors, and radio frequency transformer to stabilize and maintain the formed plasma, preventing arc interruption or extinction. The capacitive coupling module 8 is divided into two paths, corresponding to the pulse path and the radio frequency path respectively, each containing a Π-type impedance matching... The system employs a matching network, coupling capacitors, and reverse-connected switching devices (IGBTs for the pulse path and MOSFETs for the RF path). An impedance matching network ensures efficient energy transfer from the pulse generation module to the electrodes. Coupling capacitors facilitate energy transfer and block DC components, resulting in a more balanced positive and negative cycle discharge. Although the average voltage is zero during the output voltage cycle, the metal electrodes have a much higher secondary electron emission coefficient than saline solution, leading to more intense negative voltage discharge and potential current asymmetry. This can cause nerve stimulation and electrode wear. The coupling capacitors convert this current asymmetry into voltage asymmetry, increasing the positive voltage and decreasing the negative voltage to achieve charge balance. The reverse-connected switching devices prevent crosstalk between the two signals, ensuring their independent operation. The FPGA control module 12, as the system's control core, uses a preset program to implement timing control of each module. It receives electrode current signals from the current probe in real time and dynamically switches between pulse excitation and RF sustaining modes based on current change characteristics (e.g., high to low current indicates vapor layer formation, low to high current indicates plasma breakdown), ensuring efficient plasma excitation and stable maintenance.

[0050] like Figure 4 , 5As shown, the three-electrode scalpel head is made of medical-grade materials. The pulse electrode and radio frequency electrode are made of biocompatible and wear-resistant metal, while the grounding electrode is designed with a tubular structure. All three are separated by insulating material. The electrode tips feature a specific shape design to facilitate electric field concentration, reduce the breakdown voltage of plasma excitation, and simultaneously meet medical biocompatibility and insulation requirements, avoiding adverse effects on human tissue. In low-conductivity scenarios such as those involving stones, the conductivity of saline solution decreases, and conventional plasma scalpels struggle to reach the breakdown threshold. Furthermore, the impedance drops rapidly after plasma breakdown, eliminating the need for such a high voltage to maintain the breakthrough. Therefore, a different design was developed. Figure 4 and Figure 5 The three-electrode surgical blade.

[0051] In low-conductivity scenarios (such as stone surgery), stones adsorb conductive ions from saline solution, and saline irrigation during surgery introduces tissue exudate, further reducing the saline solution's conductivity. Conventional plasma scalpels struggle to stably excite and maintain plasma. However, the scalpel of this invention, through the bipolar pulse design of the pulse generation module 6, can overcome the resistance threshold of low-conductivity media, rapidly exciting plasma. This is then continuously maintained by the high-frequency sine wave from the radio frequency generation module 7. Combined with the efficient energy transfer of the capacitive coupling module and the precise control of the FPGA control module 12, this effectively solves the problems of slow and unstable vapor layer formation, difficulty in plasma excitation, and unstable maintenance in low-conductivity scenarios. Furthermore, the design of the capacitive coupling module 8 avoids direct DC and low-frequency leakage current reaching the patient, reducing DC corrosion and damage to the electrodes, thus improving surgical safety and electrode lifespan.

[0052] In actual use, attention should be paid to the installation and maintenance of the system. During installation, ensure that the system is properly grounded to avoid electromagnetic interference. Electrode cables should be connected according to the specified length to prevent signal attenuation. After use, the electrodes should be cleaned in time to remove residual tissue or stone debris. The working status of each module and the insulation performance of the electrodes should be checked regularly to ensure long-term stable operation of the system and to ensure the safety and effectiveness of the surgery.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A capacitively coupled three-electrode plasma surgical scalpel for use in low-conductivity scenarios, characterized in that, This includes a three-electrode scalpel and a power supply unit that provides power to the three-electrode scalpel, wherein: The three-electrode surgical knife includes a pulse excitation electrode, a radio frequency sustaining electrode, a ground electrode, and a current probe; the power supply unit includes an EMI filtering module, a PFC power correction module, an LLC resonant converter module, a full-bridge rectifier module, a pulse generation module, a radio frequency generation module, a capacitive coupling module, and an FPGA control module, wherein: The pulse generation module is used to generate bipolar high-voltage pulses, which are transmitted to the pulse excitation electrode via a capacitive coupling module to excite plasma in a low-conductivity medium. The radio frequency generation module is used to generate high-frequency sinusoidal radio frequency energy, which is transmitted to the radio frequency sustaining electrode via the capacitive coupling module to sustain the formed plasma. The FPGA control module is used to receive the current signal detected by the current probe and control the switching between the pulse generation module and the radio frequency generation module according to the current change characteristics. The capacitive coupling module is used to transmit the energy output from the pulse generation module and the radio frequency generation module to the three-electrode scalpel and to block the DC component. The connection relationships are as follows: The input of the EMI filter module is connected to a 220V AC mains power supply, and its output is connected to the input of the PFC power correction module. The output of the PFC power correction module is connected to the input of the LLC resonant converter module. The output of the LLC resonant converter module is connected to the input of the full-bridge rectifier module. The output of the full-bridge rectifier module is connected to the inputs of both the pulse generation module and the RF generation module. The outputs of both the pulse generation module and the RF generation module are connected to the input of the capacitive coupling module. The output of the capacitive coupling module is connected to both the pulse excitation electrode and the RF sustaining electrode. The current probe is connected to the signal input of the FPGA control module. The signal output of the FPGA control module is connected to the control terminals of both the pulse generation module and the RF generation module. The grounding electrode has a tube wall structure.

2. The capacitively coupled three-electrode plasma surgical scalpel for low conductivity applications according to claim 1, characterized in that, The capacitive coupling module includes a pulse coupling branch and a radio frequency coupling branch; the input terminal of the pulse coupling branch is connected to the output terminal of the pulse generation module, and the output terminal is connected to the pulse excitation electrode; the input terminal of the radio frequency coupling branch is connected to the output terminal of the radio frequency generation module, and the output terminal is connected to the radio frequency sustaining electrode.

3. The capacitively coupled three-electrode plasma surgical scalpel for low conductivity applications according to claim 2, characterized in that, The pulse coupling branch includes a first The impedance matching network, the first coupling capacitor, and the first switching device IGBT connected in reverse series, wherein: The first A type of impedance matching network is used to coordinate the pulse generation module and the RF generation module to transmit pulse energy at maximum power. The first coupling capacitor is used to transmit the bipolar high voltage pulse to the scalpel electrode and block the DC component to make the positive and negative periodic discharge more balanced, and to convert the current asymmetry caused by the difference in the secondary electron emission coefficient into voltage asymmetry, thereby increasing the positive voltage and decreasing the negative voltage to achieve charge balance. The first switching device, IGBT, is used to isolate the bipolar pulse signal output by the radio frequency generation module; The connection relationships are as follows: The first The input terminal of the impedance matching network is connected to the output terminal of the pulse generation module, and the output terminal is connected to the pulse excitation electrode through the first coupling capacitor; the first IGBT, which is connected in reverse series, is connected in parallel to the first... The output of the impedance matching network is connected to the first coupling capacitor.

4. The capacitively coupled three-electrode plasma surgical scalpel for low conductivity applications according to claim 2, characterized in that, The radio frequency coupling branch includes a second The impedance matching network, the second coupling capacitor, and the second switching device MOSFET connected in reverse series, wherein: The second A type of impedance matching network is used to coordinate the pulse generation module and the RF generation module to maximize the power transmission of RF energy. The second coupling capacitor is used to transmit high-frequency sinusoidal radio frequency energy to the scalpel electrode and block the DC component to make the positive and negative periodic discharge more balanced. It converts the current asymmetry caused by the difference in the secondary electron emission coefficient into voltage asymmetry, thereby increasing the positive voltage and decreasing the negative voltage to achieve charge balance. The second switching device, a MOSFET, is used to isolate the high-frequency sinusoidal radio frequency signal output by the pulse generation module; The connection relationships are as follows: The second The input terminal of the impedance matching network is connected to the output terminal of the RF generation module, and the output terminal is connected to the RF sustain electrode through a second coupling capacitor; the second switching device MOS transistor, which is connected in reverse series, is connected in parallel to the second... The output of the impedance matching network is connected to the second coupling capacitor.

5. The capacitively coupled three-electrode plasma surgical scalpel for low conductivity applications according to claim 1, characterized in that, The pulse generation module uses a bipolar Marx generator circuit, and the average voltage during the bipolar pulse period is zero.

6. The capacitively coupled three-electrode plasma surgical scalpel for low conductivity applications according to claim 1, characterized in that, The radio frequency generation module includes a full-bridge inverter circuit, a filter capacitor, and an radio frequency transformer; the input terminal of the full-bridge inverter circuit is connected to the output terminal of the full-bridge rectifier module, and the output terminal is filtered by the filter capacitor and then transformed by the radio frequency transformer to output a high-frequency sine wave.

7. The capacitively coupled three-electrode plasma scalpel for low conductivity applications according to claim 1, characterized in that, The FPGA control module determines the formation of a vapor layer based on the change in current from high to low detected by the current probe, and determines plasma breakdown based on the change in current from low to high. When plasma breakdown is detected, the pulse generation module is turned off and the radio frequency generation module is started.

8. The capacitively coupled three-electrode plasma surgical scalpel for low conductivity applications according to claim 1, characterized in that, The EMI filtering module consists of a common-mode capacitor, a differential-mode capacitor, and a common-mode inductor, and is used to filter out common-mode and differential-mode interference signals in the power grid.

9. The capacitively coupled three-electrode plasma scalpel for low conductivity applications according to claim 1, characterized in that, The PFC power correction module includes a full-bridge rectifier circuit and a boost circuit, and optimizes the power factor through MOSFETs.

10. The capacitively coupled three-electrode plasma surgical scalpel for low conductivity applications according to claim 1, characterized in that, The LLC resonant converter module consists of a full-bridge inverter circuit, an LLC resonant network, and a transformer, and achieves energy conversion and wide voltage load output through soft switching.

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