Plasma probe with improved ignition behavior

Abstract

The invention relates to a plasma probe with improved ignition behavior. The plasma probe (10) of the invention comprises a fluid line (14) which is preferably configured as a hose and an electrode (17) arranged therein, the tip (20) of the electrode (17) being located near the outlet opening (16). The electrode (17) comprises a surface section (21) of a hydrophobic configuration. Alternatively, additional elements of the plasma probe (10), in particular near the outlet opening (16), can be provided with a hydrophobic surface. Due to the persistence of the discharge base point obtained, such a probe comprises a significantly improved ignition readiness and an improved stability.

Description

Technical Field

[0001] The present invention relates to a plasma probe, in particular to plasma coagulation of biological tissues. Further, the present invention particularly relates to a plasma probe for endoscope use. Background Art

[0002] A plasma probe is known from DE 69 636 399 T2, which consists of a tube made of a flexible material. The tube is guided through the working channel of an endoscope in the patient's body. The tube comprises an end piece made of a temperature-resistant material, such as PTFE or ceramic. Similarly, the tube can consist of PTFE (polytetrafluoroethylene). An electrode is arranged in a channel enclosed by the tube and the end piece, the tip of which does not protrude from an opening of the tube or the end piece. The electrode is connected to a voltage source. An inert gas, such as argon, flows through the channel enclosed by the tube so that a plasma jet is output from the probe. A regulator unit thus allows the volume flow of the gas to be adjusted, which volume flow can provide at least two different amounts of gas flow. In standby operation, the gas flow is low. In order to ensure that the fluid entering the probe is ejected from the probe during plasma ignition, the gas flow is increased during operation. This makes it possible to avoid the accumulation of blood residues in the tube, which would lead to a risk of infection during a subsequent operation on another patient (compare paragraph

[0040] ).

[0003] Another plasma probe is known from DE 100 30 111 B4, which consists of a thin hose with a heat-resistant distal end piece and an electrode arranged in the lumen of the hose. The electrode is formed in particular by a metal plate provided with a distal tip, the longitudinal edges of which are supported at the inside of the hose.

[0004] A plasma probe with a hose made of PTFE or a similar material is known from EP 0 957 793 B2. The hose is provided with an end piece at the distal end, which end piece consists of PTFE or ceramic. The electrodes are arranged in the hose, around which flows a rare gas, which is transported through the hose and forms a plasma jet. Again, the gas flow can be reduced in the standby phase and increased during activation to avoid body fluids entering other patients with the aid of the probe and transferring body fluids to other patients.

[0005] In addition, EP 0 957 793 B2 proposes a plasma probe whose end piece is made of ceramic. A tubular electrode is directly connected to the proximal end of the hollow shaft of the ceramic end piece, so that the inner diameter of the electrode corresponds to the inner diameter of the ceramic end piece. This arrangement is used for coagulation of larger tissue areas.

[0006] In practice, the above-mentioned probes occasionally show a poor ignition behavior, which means that in order to form a plasma discharge, either extremely high voltages must be used or the probe must be brought close to the tissue to be treated. Summary of the invention

[0007] Starting from this, it is an object of the present invention to provide a plasma probe with improved ignition behavior.

[0008] This object is solved by a plasma probe according to claim 1:

[0009] The plasma probe of the present invention comprises a flexible fluid line which may be formed of a hose made of a suitable plastic material such as, for example, PTFE or another suitable plastic. The fluid line restricts at least one channel. Its proximal end may be connected to a gas source. The gas source is used to supply a defined gas flow to the channel, which leaves an outlet opening formed at the distal end of the fluid line.

[0010] In addition, the plasma probe comprises an electrode, which can be connected to a power supply via an electric wire. The wire can be a metal wire or a stranded wire extending through a channel or a conductor guided on the wall of a hose or in the wall of a hose. The power supply can be a radio frequency generator, as it is provided in medical equipment for supplying such probes. The electrode is preferably arranged close to the outlet opening. The end of the electrode, which is preferably formed in a pointed manner, is preferably arranged so that it does not protrude from the outlet opening. In doing so, damage to biological tissue caused by the mechanical influence of the electrode can be avoided. As an alternative, the electrode can extend through the outlet opening and can carry a blunt body at the end, which is preferably electrically insulated to avoid damage to the tissue. This probe is suitable for omnidirectional lateral plasma output.

[0011] According to the invention, a hydrophobic surface section is formed on the electrode. Preferably, this refers in particular to a section of the electrode near or adjacent to the distal end of the electrode. The surface of the electrode can also be configured hydrophobic as a whole.

[0012] Due to the hydrophobic configuration of the surface of the electrode, its ignition behavior is significantly improved. If the plasma probe is wetted during its introduction into an endoscope liquid (e.g., flushing liquid), such liquid tends to enter the open outlet opening of the plasma probe. Such droplets can affect the gas flow, can create turbulence and asymmetry in the gas flow, and can hinder the electron emission at the tip of the electrode. However, if the electrode is water-repellent (hydrophobic), this effect is reduced or avoided.

[0013] The hydrophobic surface section of the electrode also avoids that during the operation of the plasma probe, biological tissue, tissue fluid or products from the biological tissue accumulate on the electrode and modify its surface conductivity. In doing so, the movement of the discharge base point is also prevented, particularly the movement of the discharge base point away from the electrode tip into the channel of the probe. In doing so, the probe is also avoided from being thermally overloaded, which would otherwise occur. Otherwise, this excessive thermal strain would also cause the deformation of the fluid line, which in turn would seriously hinder the generation of gas flow and plasma flow. Moreover, direct contact between the electrode and the tissue may occur when the corresponding probe is damaged. The present invention substantially or completely avoids the consequences of moving the discharge base point.

[0014] A waterproof configuration of the electrode, in particular its surface section close to the tip, can additionally lead to an increased readiness for ignition, in particular in unfavorable situations, ie in particular under wet conditions of use.

[0015] The plasma probe of the invention may comprise a fluid line which itself consists of a heat-resistant material or is provided at its distal end with a heat-resistant end piece through which the channel extends. The end piece may have an inner diameter which corresponds to the inner diameter of the hose or is also slightly smaller than the inner diameter of the hose. Preferably, the electrode extends at least partially in the end piece so that the discharge base point is arranged shortly before the outlet opening in the end piece.

[0016] In addition to the hydrophobic surface sections formed on the electrodes, additional hydrophobic surface sections can also be provided. In doing so, capillary effects can be avoided. This means that, on the one hand, it is possible to blow out the liquid more easily and, due to the reduction of the capillary effect, the absorption of liquid can be reduced. For this purpose, the end piece and / or the hose can include a hydrophobic surface section, in particular on the inside adjacent to the channel, but, if necessary, also around the outlet opening and / or at the outside of the end piece and / or the hose. With these measures, the ignition readiness and stability of the probe can be significantly supported.

[0017] In addition, the electrode can be configured in a hollow manner so that the electrode comprises a channel through which the gas can flow. The electrode can be provided with a hydrophobic surface, in particular near its distal end or also completely on its outside. It is also possible to provide a channel surrounded by an electrode with a hydrophobic surface.

[0018] In addition, a flow guiding element made of metal or an electrical insulator, such as plastic or ceramic, can be provided for supporting the electrode in the channel and / or for influencing the gas flow, whereby the flow guiding element can be configured to reduce the gas flow in the center of the cross section (i.e. in the vicinity of the electrode) compared to the peripheral area of ​​the cross section. Moreover, such a measure serves to improve the ignition readiness. The flow guiding element can also be provided with a hydrophobic surface and can be provided with a hydrophobic surface structure or coating for this purpose.

[0019] In order to configure the desired surface segments hydrophobically, these surface segments can be provided with a hydrophobic coating, for example, silicone oil, fluoropolymers such as, for example, polytetrafluoroethylene, parylene, PFA (perfluoroalkoxy), polyamide, polyethylene, silicone elastomers, etc. For example, the hydrophobic coating can be applied by a PVD or CVD process. In addition or as an alternative, a water-repellent effect of the corresponding surface segments can be achieved by microstructuring the surface. For this purpose, the corresponding surface segments can be provided with a plurality of intersecting finest grooves, which retain a pattern of microprotrusions, which with their faces keep the liquid droplets away from the bottom of the grooves so that the liquid can easily drip off. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Further details of preferred embodiments of the invention are subject matter of the dependent claims and of the described figures. The figures show:

[0021] Figure 1 A schematic diagram shows a medical device having a plasma probe attached thereto,

[0022] Figure 2 The longitudinal section of the distal end section shows Figure 1 The plasma probe,

[0023] FIG. 3A to FIG. 3D The longitudinal section at its distal end is enlarged to show the Figure 2 Different embodiments of electrodes of a plasma probe,

[0024] Figure 4 A modified embodiment of the plasma probe of the invention is shown in a longitudinal cross-sectional view of its distal end,

[0025] Figure 5 Another embodiment of the plasma probe of the present invention is shown in a longitudinal cross-sectional view of its distal end,

[0026] Figure 6 The distal end view shows Figure 5 The plasma probe,

[0027] Figure 7 and Figure 8 Additional embodiments of the plasma probe of the invention are shown in longitudinal cross-section, respectively, of its distal end,

[0028] Fig. 9 Shown according to Figure 8 The plasma probe, which illustrates the flow profile,

[0029] Fig.10 An embodiment of the plasma probe of the present invention is shown in a longitudinal cross-sectional view of its distal end. DETAILED DESCRIPTION

[0030] Figure 1 The plasma probe 10 is illustrated as it can be used in an endoscope without further description to perform plasma treatment on a patient. To this end, the plasma probe 10 is connected to a supply device 11 or a device arrangement, which is arranged to supply the plasma probe 10 with electric current and an inert gas. To this end, the device includes a generator, for example, an RF generator 12, configured to output a radio frequency alternating voltage sufficient to ignite and maintain a plasma discharge.

[0031] A gas source 13 supplying a suitable gas, such as argon, is used to supply the inert gas. The gas source 13 is thus configured to supply the gas in a dosed and controlled manner to supply a suitable volume flow of the gas to the plasma probe 10.

[0032] The plasma probe 10 is connected at its proximal end to an RF generator 12 and a gas source 13, for example, via suitable connectors.

[0033] The plasma probe 10 is essentially composed of a flexible fluid line 14, for example, in the form of a plastic hose. It can be composed of PTFE or another plastic suitable for medical applications. The fluid line 14 surrounds a channel 14a, which leads to an outlet opening 16 arranged at the distal end 15 of the hose 14. An electrode 17 is arranged in the distal end 15, for example, in the form of a metal needle or wire that is pointed at the end. Although the distal end of the electrode 17 is arranged in the channel 14a, it is preferably approximately centered so that it does not protrude from the outlet opening 16, but the proximal end of the electrode 17 is connected to a suitable wire 18 leading to the generator 12.

[0034] In order to position the electrode 17 in the channel 14a, a suitable holding device can be provided, for example, a plate-shaped holder 19, which is diametrically positioned in the channel 14a, and which is supported with two longitudinal edges on the inner wall of the hose 14. The electrode 17 can be clamped, welded or connected to the holder 19 in another way, or the electrode 17 and the holder 19 can be configured as a single part, for example, as a diamond-shaped metal plate part, the tip of which occupies the position of the tip 20 of the electrode 17 and the longitudinal edges of which are supported on the inside of the hose 14.

[0035] According to the invention, the electrode 17 comprises at least one hydrophobic surface section 21. It preferably surrounds at least the distal end of the electrode 17. The hydrophobic surface section 21 can in particular cover the cylindrical peripheral surface of the electrode 17. Figure 3AA hydrophobic surface section 21 is illustrated, which may be created by a water-repellent coating of the electrode 17. The electrode 17, consisting of, for example, tungsten or another metal, is provided on its outer peripheral surface with a layer of a water-repellent material, for example, PTFE, silicone oil, etc. Preferably, however, the tip 20 or a section thereof is blank, i.e. uncoated, and the expression "tip" therefore means a generally tapered, e.g. conical shaped section of the electrode 17.

[0036] The electrode 17 may also be provided with a coating which extends into the region forming the tip of the hydrophobic surface section 21. Thus, the coating may extend with an unreduced thickness up to its end 21a, or as Figure 3C As shown in FIG. 1 , the electrode 17 may extend toward its end 21a in a manner of continuously or gradually decreasing thickness. In addition, each of the electrodes 17 may support a layer 17a having good conductivity, for example, a silver layer, as shown in FIG. Figure 3D According to Figure 3B The layer 17a is covered by a coating of a hydrophobic surface section 21 up to the tip or into the region of the tip 20. The electrode 17 itself can consist of stainless steel, steel, tungsten, hard metal or another refractory material.

[0037] The water repellent effect in the hydrophobic surface section 21 can be achieved by the low surface energy of the material used (preferably below 20 mJ / m 2 ). Additionally or alternatively, the hydrophobic effect in the surface segment 21 can be achieved by microstructuring of the surface. For this purpose, the surface segment 21 is formed so that many very small peak-shaped protrusions protrude radially from it. This can be achieved, for example, in that the surface segment 21 is first provided with a spiral groove and subsequently with an axial groove, for example, with the aid of a laser. Thus, the length of the remaining protrusions and their distances from each other are adjusted in a coordinated manner so that a water drop placed on the tip of these protrusions does not come into contact with the bottom of the groove due to its own surface tension, wherein a meniscus is formed between the protrusions. Moreover, other methods for microstructuring or influencing the surface roughness can be applied, such as dry etching or the application of nanoparticles.

[0038] The tip 20 may be hydrophobic due to its tapered surface and the large curvature of its tip.

[0039] In addition, the holder 19 may have a hydrophobic surface section 22, which completely or partially covers the surface of the holder 19. In addition, the hydrophobic surface section 22 can be obtained by suitable microstructuring of the surface or by coating it with a water-repellent material. The above description with reference to the electrode 17 and the hydrophobic surface section 21 applies accordingly to the structuring or coating material of the surface.

[0040] In addition, the hose 14 can be configured in a hydrophobic manner on the inside and / or outside and include corresponding hydrophobic surface sections 23, 24. Similarly, its face can be hydrophobic. This can be achieved by suitable material selection, for example, where the hose 14 consists of PTFE. The hydrophobic effect of its surface can be increased by the above-mentioned microstructuring and / or coating or material selection.

[0041] The plasma probe 10 described thus far operates as follows:

[0042] During operation, a gas flow (eg, argon flow) with a defined amount flows through the channel 14a. For example, a radio frequency alternating voltage is applied to the electrode 17. The patient is connected to the neutral electrode. Starting from the tip 20, a plasma flow is formed that hits the tissue.

[0043] During interruptions in operation or before the start of operation, liquid, for example, water, body fluids, flushing liquids, etc., can reach the outlet opening 16. However, the hydrophobic surface sections 21 and also 22, 23, 24 prevent liquid from entering the channel 14a or at least prevent droplets from adhering to the channel 14a and the electrode 17. Therefore, a very low gas flow is sufficient to keep the electrode 17 and the channel 14a free of liquid from entering. The electrode 17, which is kept dry in this way, can be easily ignited at a large distance from the tissue. Therefore, maintaining a low gas flow supports the ignition preparation.

[0044] This also applies during the introduction of the plasma probe 10 into the patient's body through an endoscope before the treatment begins. Also in this case, liquid can enter the channel 14a, which can already be flushed away from the electrode 17 in the case of very low gas flow.

[0045] The invention thus far described is generally susceptible of numerous modifications.

[0046] Figure 4 A modified plasma probe 10 is shown, with Figure 2 Compared to the plasma probe 10 of the embodiment of the present invention, the plasma probe 10 further comprises a ceramic insert 30 in the distal end 15 of the hose 14. The insert 30 comprises an elongated handle 31 configured in a hollow manner, which is inserted into the hose 14. The channel 14a extends through the hose 14 and the handle 31 up to the outlet opening 16. The tip 20 of the electrode 17 is arranged in the insert 30, preferably near the outlet opening 16. The handle 31 is used for heat distribution and dissipation. The insert 30 may be provided with a hydrophobic surface section 25 on its outer side in the region of its distal end. Similarly, it may comprise a hydrophobic surface section 26 on its wall at the inner side. Due to appropriate material selection and / or structuring of the surface, the waterproof effect of the surface sections 25, 26 may be achieved in each of the above-described ways. In addition, with reference to Figure 1and Figure 2 The description provided applies accordingly.

[0047] exist Figure 5 and Figure 6 The following diagram is shown separately again according to Figure 2 The plasma probe 10 of FIG. 1 is a schematic diagram of a plasma probe 10. The holder 19 may be configured as a cooling element and may have one or more recesses at its hose side edge, which minimize the contact surface with the hose. The holder 19 may be made of metal, ceramic material or plastic material or elastomer (such as, for example, silicon). Figure 6 As shown in FIG. 1 , flow channels 33 , 34 are provided on both sides of the holder 19 , through which flow channels a gas, for example argon, can flow to the open hose end. Fig. 9 The exiting gas flow 35 and the plasma formed therein are illustrated.

[0048] Again, if Figure 5 As shown in , the electrode 17 may include a hydrophobic surface segment 21, which preferably extends from the tip 20 all the way to the holder 19. The holder 19 may also include hydrophobic surface segments 27, 28 on its face and / or in the flow channels 33, 34. The surface segments 27, 28 may be hydrophobic because the holder 19 itself consists of a hydrophobic material, because it is covered with a hydrophobic material and / or because its surface is microstructured to provide a lotus effect. Regarding the microstructuring, the explanations provided in the context of the electrode 17 apply accordingly. Apart from this, the above reference Figures 1 to 4 The description given here also applies in a supplementary manner to Figure 5 and Figure 6 Embodiment of the invention.

[0049] exist Figure 7 A further modified embodiment of the plasma probe 10 is illustrated in FIG. Figure 5 and Figure 6 Description of the plasma probe 10 of . However, in contrast thereto, the electrode 17 is hollow and is therefore configured without a tip. It surrounds the narrow channel 36. The electrode 17, which is therefore configured as a small tube, is again connected to a wire 18 or another conductor. Its distal end does not protrude through the outlet opening 16. For example, on its outer side, the electrode 17 again carries a hydrophobic coating. The surface section 21 can be hydrophobic because the electrode 17 itself consists of a hydrophobic material, because it is coated with a hydrophobic material and / or because its surface is microstructured to provide a lotus effect.

[0050] from Figure 8Further modifications of the plasma probe 10 of the invention are evident. The plasma probe 10 shown here comprises two holders 19a, 19b for supporting an electrode 17, which holders extend across the lumen of the hose and can be arranged in a manner rotatable about each other around the electrode 17. Each of the elements shown, in particular the electrode 17 and one or both of the holders 19a, 19b, can have a hydrophobic surface and for this purpose can consist of a hydrophobic material or can be configured in a hydrophobic manner by a layer with a hydrophobic material or by surface structuring.

[0051] The electrode 17 is not necessarily in a retracted position behind the outlet opening 16 in the channel 14a. Fig.10 Obviously, the electrode 17 can also be extended outside the outlet opening 16. In this case, the electrode 17 is preferably provided with a blunt (preferably insulating) body 37, such as a ceramic ball, which avoids direct current-generating contact between the electrode 17 and the surrounding biological tissue and mechanical damage to the tissue by the electrode 17. The electrode 17 can be supported by a holder 19, such as Fig.10 As shown in or also by Figure 8 A similar plurality of holder supports. The electrode 17 may have a tip 38 as a discharge base point, which is arranged in front of the outlet opening 16 and extends radially away from the electrode 17. The electrode 17 may again include a hydrophobic surface segment 21. Another hydrophobic surface segment 29 may be formed on the insulator 37 and may cover it completely or partially. The surface segment 29 may be hydrophobic because the insulator 37 itself consists of a hydrophobic material, because it is coated with a hydrophobic material and / or because its surface is microstructured to provide a lotus effect. Apart from this, the above description also applies accordingly, in particular with regard to the configuration of the hydrophobic surface segments 21 to 27.

[0052] In accordance with Figures 5 to 10 In all embodiments of the present invention, a hollow cylindrical insert for thermal protection of the hose 14 can be inserted into the distal end 15 of the hose 14. The inner diameter of this insert can correspond to the inner diameter of the channel 14a or can also be slightly smaller than the inner diameter of the channel 14a. The insert can be hydrophobic, in particular on its inner wall and / or on at least one of its faces. To this end, the insert itself can consist of a hydrophobic material, can be coated with a hydrophobic material and / or can be microstructured on the surface in order to provide a lotus effect.

[0053] The plasma probe 10 according to the invention comprises a fluid line 14, which is preferably configured as a hose and an electrode 17 arranged therein, the tip 20 of which is placed near the outlet opening 16. The electrode 17 comprises a surface section 21 of a hydrophobic configuration. Alternatively, additional elements of the plasma probe 10, in particular near the outlet opening 16, can be provided with a hydrophobic surface. Such a probe comprises a significantly improved ignition preparation and comprises an improved stability due to the persistence of the generated discharge base point.

[0054] List of reference numerals:

[0055] 10 Plasma probe

[0056] 11 Equipment

[0057] 12 RF generator

[0058] 13 Gas source

[0059] 14 Fluid lines (plastic hoses)

[0060] Channel 14a

[0061] 15 Distal end of fluid line

[0062] 16 Exit opening

[0063] 17 Electrode

[0064] 18 lines

[0065] 19 Retainer

[0066] 20 Tip of electrode 17

[0067] 21-29 Hydrophobic surface segment

[0068] 21a End of the hydrophobic surface segment

[0069] 30 Inserts

[0070] 31 handles

[0071] 32 Depression

[0072] 33 Flow Channel

[0073] 34a Flow channel

[0074] 35 Gas flow

[0075] 36 channels

[0076] 37 Insulator

[0077] 38 Tip.

Claims

1. A plasma probe (10), A fluid line (14) is provided which defines at least one channel (14a) which can be connected to a gas source (13), wherein The channel (14a) opens to the distal end (15) of the fluid line (14) and terminates there in an outlet opening (16), having an electrode (17) near the outlet opening (16), the electrode (17) being connectable to a power source (12) via a line (18), Characterized in that a hydrophobic surface section (21) is formed on the electrode (17) and a retainer (19) is arranged on or in the distal end (15), wherein the retainer (19) is connected to the electrode (17) and attached to the fluid line (14) for placing the electrode (17) in the channel (14a).

2. The plasma probe according to claim 1, characterized in that The fluid line (14) is a flexible hose made of an electrically insulating material, an electrically insulating heat-resistant end piece (30) is held in the distal end (15) of the flexible hose, and the passage (14a) extends through the electrically insulating heat-resistant end piece (30).

3. The plasma probe according to claim 2, characterized in that: The electrode (17) is at least partially arranged within the end piece (30).

4. The plasma probe according to claim 2 or 3, characterized in that: A hydrophobic surface section (26) is additionally formed on the end piece (30) and / or the hose.

5. The plasma probe according to any one of claims 1 to 3, characterized in that The electrode (17) is hollow and comprises a hydrophobic surface section (21) on its outer side.

6. The plasma probe according to claim 1, characterized in that In addition, hydrophobic surface sections (27, 28) are formed on the holder (19).

7. The plasma probe according to any one of claims 1 to 3, characterized in that The hydrophobic surface segment (21) defines a wetting contact angle (α) with water which is greater than 90°.

8. The plasma probe according to any one of claims 1 to 3, characterized in that The surface energy of the hydrophobic surface segment (21) is less than 20 mJ / m 2 .

9. The plasma probe according to any one of claims 1 to 3, characterized in that The hydrophobic surface section (21) is formed of a hydrophobic material.

10. The plasma probe according to claim 1, characterized in that: The holder (19) comprises at least two channels (33, 34) extending along the electrode (17).

11. The plasma probe according to claim 1, characterized in that: The plasma probe (10) is used for plasma coagulation of biological tissue.

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