Method and apparatus for instrument advancement

Abstract

Embodiments generally relate to propulsion tube units and propulsion devices for advancing an instrument along a passageway, and associated methods of use. For example, the instrument can include tools, sensors, probes, and / or monitoring devices for medical use, such as endoscopy, or industrial use, such as mining. In some embodiments, the propulsion device can include an elongated tube defining a channel configured to contain a liquid and a pressure actuator in communication with the channel. The pressure actuator can be configured to selectively adjust a pressure of the liquid in the channel to alternately: decrease the pressure to induce cavitation in the liquid and form bubbles; and increase the pressure to collapse some or all of the bubbles back into the liquid, thereby accelerating at least a portion of the liquid toward the first end of the tube and imparting momentum to the tube to advance the tube along the passageway.

Description

Technical Field

[0001] The implementation generally relates to a propulsion tube unit and propulsion device for advancing an instrument along a pathway, and associated methods of use. For example, the instrument may include tools, sensors, probes, and / or monitoring devices for medical purposes (such as endoscopy) or industrial purposes (such as mining). The described implementation can also be applied to other applications for advancing instruments along pathways. Background Technology

[0002] There are many existing methods and devices for advancing instruments along pathways, including applications in mining and medicine such as endoscopy. Advancing conventional endoscopic equipment along a patient's passageways or lumens presents numerous difficulties, and these difficulties can introduce associated risks of harm to the patient.

[0003] The aim is to address or improve one or more shortcomings or deficiencies associated with existing propulsion devices used to advance instruments along a path, or at least to provide a useful alternative.

[0004] Any discussion of documents, actions, materials, devices, articles, etc., already included in this specification shall not be construed as an admission that any or all of these matters existed prior to the priority date of each claim of this application and formed part of the prior art or as common general knowledge in the field relating to this disclosure.

[0005] Throughout this specification, the word “comprising” or variations such as “including” will be understood to imply the inclusion of the stated elements, integers or steps or groups of elements, integers or steps, but does not exclude any other elements, integers or steps or groups of elements, integers or steps. Summary of the Invention

[0006] Some implementations involve a propulsion device for advancing an instrument along a path, the propulsion device comprising:

[0007] An elongated tube includes a first end and a second end opposite the first end, the tube defining a channel configured to contain liquid, the first end of the channel being closed at or near the first end of the tube, and the second end of the channel being defined by the second end of the tube; and

[0008] A pressure actuator, which communicates with a second end of the channel, is configured to selectively regulate the pressure of the liquid in the channel to alternately:

[0009] Reducing the pressure to induce cavitation and form bubbles in the liquid; and

[0010] The pressure is increased to cause some or all of the bubbles to collapse back into the liquid, thereby accelerating at least a portion of the liquid toward the first end of the tube and transferring momentum to the tube to advance the tube along the passage.

[0011] Some implementation schemes involve a propulsion tube unit that includes:

[0012] An elongated tube includes a first end and a second end opposite the first end, the tube defining a channel configured to contain liquid, the first end of the channel being closed at or near the first end of the tube, and the second end of the channel being defined by the second end of the tube; and

[0013] A piston assembly connected to the second end of the tube, the piston assembly comprising:

[0014] The main body, which defines an orifice in fluid communication with the channel of the tube; and

[0015] A movable piston is disposed within the bore and configured to seal against the inner surface of the bore.

[0016] The piston assembly and the tube cooperate to define a sealed container holding a selected mass of liquid and a selected mass of gas.

[0017] The piston assembly can be configured to cooperate with an actuator to achieve movement of the piston, thereby selectively regulating the pressure of the liquid in the channel to alternately: decrease the pressure to induce cavitation and form bubbles in the liquid; and increase the pressure to cause some or all of the bubbles to collapse back into the liquid, thereby accelerating at least a portion of the liquid toward a first end of the tube and transferring momentum to the tube to advance the tube along the passage.

[0018] In some embodiments, the propulsion device or propulsion tube unit may include one or more mechanisms configured to promote cavitation in one or more regions of the channel when pressure decreases, wherein the one or more regions extend along at least a portion of the length of the channel. The one or more mechanisms may be configured to promote cavitation in a plurality of spaced-apart regions along at least a portion of the length of the channel. The one or more mechanisms may include surface variations on the inner surface of the channel.

[0019] The surface change may include a coating. The coating may include a hydrophobic material. The coating may include a catalytic material. The coating may include one or more coatings selected from the following: octadecyltrichlorosilane, silane compounds, polychloro-p-xylene, fluorinated copolymers, PTFE (Teflon). TMManganese oxide polystyrene (MnO2 / PS), nano-composite zinc oxide polystyrene (ZnO / PS), nano-composite precipitated calcium carbonate, fluorinated acrylate oligomers, polyurethane, acrylic acid, polyvinylpyrrolidone (PVP), polyethylene oxide, a combination of hydroxyethyl methacrylate and acrylamide, or other hydrophobic compounds.

[0020] Surface variations can include topographic variations. Topographic variations can have surface roughness in the range of, for example, about 0.1 μm to 500 μm, about 0.5 μm to 100 μm, or about 1 μm to 10 μm.

[0021] Topographical variations can include scratched or dented surfaces. Topographical variations can define multiple V-shaped channels. The characteristic angles of the V-shaped channels can range, for example, from about 10° to 90°, from about 30° to 60°, or from about 40° to 50°. The average width of the V-shaped channels can range, for example, from about 1 μm to 10 μm or from about 2 μm to 4 μm.

[0022] Topographical variations can define multiple conical depressions. The characteristic angles of the conical depressions can range, for example, from about 10° to 90°, from about 30° to 60°, or from about 40° to 50°. The average width of the conical depressions can range, for example, from about 1 μm to 10 μm or from about 2 μm to 4 μm.

[0023] Topographical variations can define multiple protrusions. The average height of a protrusion can range, for example, from about 0.1 μm to 1 mm, from about 1 μm to 500 μm, or from about 10 μm to 100 μm. The average width of a protrusion can range, for example, from about 0.1 μm to 500 μm, from about 0.5 μm to 100 μm, or from about 1 μm to 10 μm. The average distance between adjacent protrusions can range, for example, from about 0.1 μm to 500 μm, from about 0.5 μm to 100 μm, or from about 1 μm to 10 μm.

[0024] In some implementations, for example, the protrusions may include nanowires or hollow nanotubes, which may be formed of materials such as carbon or silicon.

[0025] For nanowires, for example, the width of the protrusions can be in the range of about 10 nm to 500 nm, about 20 nm to 300 nm, or about 100 nm to 200 nm; the length or height of the protrusions 835 can be in the range of about 0.1 μm to 100 μm, about 1 μm to 50 μm, or about 10 μm to 20 μm; and the average spacing between the protrusions can be in the range of about 10 nm to 10 μm, about 10 nm to 100 nm, or about 100 nm to 1 μm.

[0026] For nanotubes, for example, the width of the protrusions can be in the range of about 10 nm to 100 nm, about 10 nm to 50 nm, or about 20 nm to 40 nm; the length or height of the protrusions can be in the range of about 1 μm to 50 μm, about 5 μm to 30 μm, or about 10 μm to 20 μm; the pore size (or inner diameter) of the protrusions can be in the range of about 1 μm to 40 μm, about 5 μm to 30 μm, or about 10 μm to 20 μm; and the average spacing between the protrusions can be in the range of about 10 nm to 10 μm, about 10 nm to 100 nm, or about 100 nm to 1 μm.

[0027] Topographical variations can define porous surfaces. Porous surfaces can include, for example, foams, sintered materials, or other porous materials. The average pore size of a porous surface can range, for example, from about 10 nm to 200 μm, from about 20 nm to 250 nm, from about 50 nm to 150 nm, from about 10 μm to about 200 μm, or from about 50 μm to about 100 μm. A porous surface can include a layer of porous material. The thickness of the porous layer can range, for example, from about 10 μm to 1 mm or from about 50 μm to 100 μm.

[0028] The one or more mechanisms may include a variation in the thermal conductivity of the tube wall along the length of the channel. The thermal conductivity of the wall may be approximately 0.25 W / m along the length of the channel. -1 K -1 It varies within the range of 240Wm⁻¹K⁻¹.

[0029] The one or more mechanisms may include one or more acoustic transducers. One or more of the acoustic transducers may be disposed within the wall of the tube. One or more of the acoustic transducers may be disposed outside the tube wall. The operating frequency of the acoustic transducers may be in the range of approximately 1 kHz to 100 kHz. The power associated with the energy of the acoustic waves acting within the cavity guided by the acoustic transducers may be in the range of approximately 10 mW to 100 mW.

[0030] In some implementations, the propulsion device can be configured to advance medical instruments along cavities within the patient's body.

[0031] In some embodiments, the channel may be a continuous, closed channel extending from a first end of the tube to a second end of the tube. The tube may be reinforced to prevent expansion or contraction due to changes in internal pressure. The tube may be formed of a material suitable for sterilization.

[0032] In some embodiments, the propulsion device may include a plurality of tubes extending side by side according to any of the embodiments.

[0033] In some implementations, the pressure actuator may include a flexible diaphragm defining a sealed chamber and an actuation mechanism configured to deform the flexible diaphragm to selectively regulate the pressure of the liquid in the channel.

[0034] In some embodiments, the pressure actuator may include a piston assembly comprising a movable piston disposed within an orifice of the piston assembly; and a drive mechanism configured to drive the piston of the piston assembly to selectively regulate the pressure of liquid in the passage. The piston assembly may be connected to a tube to form a sealed tube unit containing liquid, and the piston assembly may be removably coupled to the drive mechanism.

[0035] Some embodiments relate to a propulsion tube unit comprising one or more tubes according to any one of the embodiments; and

[0036] A piston assembly connected to the second end of the tube, the piston assembly comprising:

[0037] The body, which defines an orifice in fluid communication with a channel in each of the one or more tubes; and

[0038] A movable piston is disposed within the bore and configured to seal against the inner surface of the bore.

[0039] Some implementations relate to a propulsion tube unit comprising: a tube according to any one of the implementations; and

[0040] A movable piston is disposed within the channel at or near the second end of the tube and is configured to seal against the inner surface of the channel.

[0041] In some implementations, the piston assembly and one or more tubes can cooperate to define a sealed container holding a selected mass of liquid and a selected mass of gas. The selected masses of liquid and gas can be selected for a specific length and diameter of the tubes. During operation, the liquid and gas can be maintained at a predetermined pressure not significantly higher than the typical channel pressure.

[0042] Some implementations involve a driver console that includes:

[0043] A housing defining a socket configured to receive and engage a propulsion tube unit according to any of the embodiments described;

[0044] Actuator, which is configured to engage the piston; and

[0045] The controller is configured to operate the actuator to move the piston, thereby selectively regulating the pressure within the passage of the tube.

[0046] Some implementations relate to a method for advancing an instrument along a path, the method comprising selectively adjusting the pressure of a liquid within a tube connected to the instrument to continuously induce cavitation of bubbles in the liquid and subsequently causing the bubbles to collapse back into the liquid to accelerate the liquid within the tube, transfer momentum from the liquid to the tube, and advance the tube along the path. Attached Figure Description

[0047] Exemplary embodiments will now be described in detail with reference to the accompanying drawings, in which:

[0048] Figure 1 This is a schematic diagram of a propulsion device based on some implementation schemes;

[0049] Figures 2A to 2F These are a series of longitudinal sections of a portion of a tube in a propulsion device according to some embodiments, showing the cycle of bubble nucleation and cavitation in a liquid contained within the tube and the subsequent collapse of the bubbles back into the liquid;

[0050] Figures 3A to 3G These are a series of longitudinal sections of a portion of a tube in a propulsion device according to some embodiments, showing the cycle of bubble nucleation and cavitation in a liquid contained within the tube and the subsequent collapse of the bubbles back into the liquid;

[0051] Figure 4 This is a longitudinal section of a portion of a tube in a propulsion device according to some embodiments, showing a mechanism for promoting bubble nucleation and / or coalescence in certain regions within the tube;

[0052] Figure 5 This is a longitudinal section of a portion of a tube in a propulsion device according to some embodiments, showing a mechanism for promoting bubble nucleation and / or coalescence in certain regions within the tube;

[0053] Figure 6 This is a longitudinal section of a portion of a tube in a propulsion device according to some embodiments, showing a mechanism for promoting bubble nucleation and / or coalescence in certain regions within the tube;

[0054] Figure 7 This is an illustration of topographic surface changes used to promote bubble nucleation, based on some implementation schemes;

[0055] Figures 8A to 8E A series of illustrations are shown of different types of protrusions for promoting bubble nucleation according to some embodiments;

[0056] Figure 9 This is an illustration of a porous surface used to promote bubble nucleation, based on some implementation schemes;

[0057] Figures 10A to 10CA series of illustrations show different types of large-scale terrain surface variations for enhancing momentum transfer between liquids and pipes, according to some implementation schemes;

[0058] Figure 11 An exemplary displacement and velocity distribution diagram according to some embodiments is shown, which illustrates the movement of the piston of a pressure actuator;

[0059] Figure 12 An exemplary pressure cycle according to some embodiments is shown, which illustrates the pressure applied to the liquid in the pipe;

[0060] Figure 13A and Figure 13B Cross-sections of two devices having multiple tubes according to some embodiments are shown, illustrating different arrangements of the tubes;

[0061] Figure 14 A schematic diagram of a portion of a propulsion device having a removable tube and piston assembly according to some embodiments is shown;

[0062] Figure 15 It shows Figure 14 The front panel of the drive control console for the propulsion device;

[0063] Figure 16 The following are shown according to some implementation schemes: Figure 14 The endoscopic system of the propulsion device; and

[0064] Figure 17 A propulsion device with alternative tube units according to some embodiments is shown. Detailed Implementation

[0065] The implementation scheme generally relates to propulsion devices for advancing instruments along a pathway and associated methods of use. For example, the instrument may include tools, sensors, probes, and / or monitoring devices for medical purposes (such as endoscopy) or industrial purposes (such as mining). The described implementation scheme can also be applied to other applications for advancing instruments along a pathway.

[0066] refer to Figure 1 The image shows a propulsion device 100 according to some embodiments. The propulsion device 100 includes: an elongated tube 110 defining an inner cavity or channel 120 configured to contain liquid 130; and a pressure actuator 140 configured to selectively regulate the pressure of the liquid 130 in the channel 120, such as by changing the pressure, optionally by continuously changing the pressure.

[0067] The first or distal end 122 of the channel 120 is closed at or near the first or distal end 112 of the tube 110. Figure 1In the diagram, the distal end 112 of the tube 110 is shown disposed in the channel or cavity 101 of the passage 103.

[0068] In some embodiments, tube 110 may be configured to be inserted into and pass through the lumen 101 of a biological conduit, such as a patient's access 103. Examples of such biological conduits include any one or more accesses of the esophagus, stomach, intestine, colon, small intestine, large intestine, duodenum, or gastrointestinal system. In some embodiments, tube 110 may be configured to be inserted into and pass through another access 103 within the patient's body, such as a blood vessel, vein, or artery. In some embodiments, tube 110 may be configured for human medical or veterinary applications. In some embodiments, for example, tube 110 may be configured for industrial applications, such as for pipes, wall openings, cable tracks, machinery, mining, or well shafts.

[0069] In some implementations, tube 110 may be configured to be housed within an insertion cannula of an endoscope, and the insertion cannula may be configured as an insertion pathway 103, such as a pathway within a patient's body. An example of this arrangement is... Figure 16 As shown in the figure. The tube 110 of the propulsion device 100 can be accommodated within a propulsion tube channel (not shown) inside the insertion tube. In some embodiments, the propulsion tube channel can be concentric or coaxial with the outer diameter of the insertion tube and can extend along the central longitudinal axis of the insertion tube. In some embodiments, the propulsion tube channel can be radially offset from the central axis of the insertion tube.

[0070] The pressure actuator 140 communicates with the second or proximal end 124 of the channel 120 at or near the second or proximal end 114 of the tube 110 opposite to the distal end 112. The channel 120 may include a continuous closed channel extending from the first end 112 of the tube 110 to the second end 114 of the tube 110.

[0071] The pressure actuator 140 may include, for example, any suitable device configured to selectively regulate the pressure of the liquid 130 in the channel 120, such as a reciprocating piston. In some embodiments, the pressure actuator 140 may include a piston driven by a motor (such as a linear motor) controlled by a controller (not shown).

[0072] The pressure actuator 140 can be configured to gradually reduce the pressure within the channel 120 to induce cavitation and form bubbles in the liquid 130, and then suddenly increase the pressure to compress the bubbles and collapse them back into the liquid 130, thereby accelerating at least a portion of the liquid 130 toward the first end 112 of the tube 110, such that momentum is transferred from the liquid to the tube 110 to propel the tube 110 along the passage.

[0073] In some embodiments, when channel 120 is at an initial or base pressure, channel 120 may contain a certain volume of gas and liquid 130, and pressure actuator 140 can be controlled to increase the pressure, thereby compressing and dissolving some or all of the gas into liquid 130. In some embodiments, channel 120 may be completely filled with liquid 130, and pressure actuator 140 may decrease the pressure to cause gas to cavitate out of liquid 130. In various embodiments, the base pressure may be set to: atmospheric pressure or near atmospheric pressure; significantly higher than atmospheric pressure; or significantly lower than atmospheric pressure.

[0074] The pressure actuator 140 can be configured to regulate the pressure in a repetitive cycle to cause bubbles to cavitate from the liquid 130, and subsequently compress some or all of the gas back into the liquid 130. In various applications, the difference between the maximum pressure and the minimum pressure in channel 120 can range, for example, from about 10 kPa to 100 MPa, from about 10 kPa to 100 kPa, from about 100 kPa to 1 MPa, from about 1 MPa to about 10 MPa, or from about 10 MPa to about 100 MPa. In some embodiments, the maximum pressure can be higher than, lower than, or close to atmospheric pressure. In some embodiments, the minimum pressure can be higher than, lower than, or close to atmospheric pressure, but has a non-zero difference from the maximum pressure.

[0075] For example, for gastrointestinal applications, the channel pressure can range from 100 kPa below atmospheric pressure to 1000 kPa above atmospheric pressure; for cardiovascular applications, the channel pressure can range from 20 kPa below atmospheric pressure to 300 kPa above atmospheric pressure; and for industrial applications, the channel pressure can range from 1000 kPa below atmospheric pressure to 10000 kPa above atmospheric pressure.

[0076] For example, the liquid 130 in channel 120 may include any one or more of the following: a pure liquid, a solution, a gas / liquid solution (i.e., a gas dissolved in a liquid), a mixture of gas and liquid, a mixture of liquid and solid particles (such as a suspension), and a mixture of two or more miscible or immiscible liquids. In some embodiments, the gas-to-liquid volume ratio at atmospheric pressure may be in the range of, for example, about 0.1% to 10%, about 0.5% to 5%, or about 1% to 2%.

[0077] For example, liquid 130 may include any suitable liquid, gas, solid particles or solution, such as: water, ethanol, carbon dioxide, nitrogen, air, nitric oxide, argon, salt, sodium chloride, potassium formate, acid, acetic acid or lithium metatungstate.

[0078] Different liquids may be suitable for different applications. For example, in medical applications, preferred liquids may be biocompatible, non-toxic (or have very low toxicity), pyrogen-free, non-inflammatory, non-hypertonic, relatively inert, and suitable for operation at relatively low pressures and temperatures similar to the typical body temperature of a patient. Examples include water, ethanol, carbon dioxide, nitrogen, air, nitric oxide, and argon.

[0079] In industrial applications where biocompatibility is not required, for example, liquids with high density may be preferred, such as aqueous solutions of inert inorganic compounds. A suitable high-density liquid could be an aqueous solution of lithium metatungstate, which has high density, low viscosity, and good thermal stability.

[0080] In various implementations, tube 110 may be formed of different materials, depending on their suitability for a given application. For example, for medical applications, tube 110 may be formed of a non-toxic material that is flexible enough to bend or turn around in a passageway within a patient's body.

[0081] Examples of materials that can be used to form tube 110 in various applications include: polymers, plastics, polyethylene, high-density polyethylene, polytetrafluoroethylene, vinyl resins, nylon, rubber, elastomers, resins, or composites containing textiles impregnated with polymers, elastomers, or resins. Polymers with voids (foam) in their internal structure can also be used to increase flexibility, such as extruded polytetrafluoroethylene (ePTFE). Composite layering of these materials can also be used to increase strength, maintain flexibility, and resist internal pressure or kinking.

[0082] The wall 118 of pipe 110 should have sufficient strength and thickness to withstand the expected pressure differential range for a given application. In some embodiments, pipe 110 or pipe wall 118 may be reinforced to mitigate expansion and / or contraction of the pipe due to pressure changes. For example, any suitable reinforcing material, such as high-strength fibers or ultra-high molecular weight polyethylene, may be used.

[0083] refer to Figures 2A to 2F The diagram shows a section of the pipe 110 of the propulsion device 100 according to some embodiments, and the cavitation process is shown in a series of figures.

[0084] refer to Figure 2A At the initial or base pressure, channel 120 can be substantially or completely filled with liquid 130, with little or no gas within channel 120. (However, in some embodiments, a significant amount of gas may be present in the channel at the base pressure.)

[0085] As the pressure in channel 120 is gradually reduced by pressure actuator 140, bubbles 133 can begin to form in the liquid 130 within channel 120, such as Figure 2BAs shown. Bubble 133 may include gas previously dissolved in liquid 130 and / or vapor (i.e., the gas phase of liquid 130). Bubble 133 may be formed by homogeneous or heterogeneous nucleation at nucleation sites in liquid 130, such as particles suspended in liquid 130 and / or located at nucleation sites on the inner surface 126 of tube 110.

[0086] As the pressure decreases further, bubble 133 can grow in volume to form larger bubble 133c, such as Figure 2C As shown, new bubbles 133 can continue to form through nucleation. Some bubbles 133, 133c can coalesce to form even larger bubbles 133d, such as... Figure 2D As shown.

[0087] Under certain conditions, bubbles 133 can coalesce to form large bubbles 133e, which span the inner cavity of channel 120, such as Figure 2E As shown. That is, the transverse bubble 133e can occupy the entire interior of the channel 120 in one region of the channel 120, such that different portions of the liquid 130 are separated on both sides of the bubble 133e. It may be desirable to induce or promote the formation of such a transverse bubble 133e in the channel 120, as this can enhance or increase the propulsion effect by increasing the acceleration of the liquid 130 during a sudden increase in pressure and thus increasing the kinetic energy imparted to the liquid 130 and the momentum transferred to the tube 110.

[0088] When the pressure increases (i.e., during compression), the liquid 130 is accelerated in the distal direction (i.e., toward the first or distal end 122 of the channel 120), such as Figure 2F As indicated by arrow 201. Due to the relatively high compressibility of bubble 133, which is several orders of magnitude higher than the relatively low compressibility of liquid 130, liquid 130 is allowed to rapidly accelerate and compress bubble 133, such as... Figure 2F As shown.

[0089] When bubbles 133 are compressed, they experience a sudden increase in pressure and density and collapse (i.e., dissolve and / or condense) back into liquid 130, as... Figure 2A As shown. The rate at which bubbles 133 dissolve / collapse into liquid 130 can be increased by increasing the total surface area of ​​the gas-liquid interface. Therefore, it may be desirable to induce or promote the formation of a number of bubbles 133, and preferably, the formation of a number of bubbles spanning 133e.

[0090] Several methods can be used to increase the likelihood of forming across bubble 133e, some of which will be discussed below. For example, in some embodiments, liquid 130 may include one or more additives to enhance bubble coalescence. In some embodiments, the inner diameter of channel 120 may be chosen to be relatively small, such that only a relatively small bubble volume is needed to cross the cavity. However, when the pressure suddenly increases, the inner diameter of the cavity should still be large enough to allow liquid 130 to flow along channel 120 (i.e., without being excessively restricted by capillary resistance). In some embodiments, propulsion device 100 may include a plurality of tubes 110 extending side by side, each tube defining channel 120. This can allow for a relatively small inner diameter of each channel 120 while maintaining a relatively high total mass of liquid 130 within the tube 110.

[0091] In some implementations, cavitation, bubble nucleation, and / or bubble coalescence can be enhanced, promoted, or facilitated in certain regions of channel 120.

[0092] In some embodiments, the propulsion device 100 may include one or more mechanisms configured to promote cavitation, bubble nucleation, and / or bubble coalescence in one or more regions of the channel when the pressure decreases. The one or more regions may extend along at least a portion of the length of the channel 120. For example, the one or more mechanisms may be configured to promote cavitation, bubble nucleation, and / or bubble coalescence in a plurality of regions spaced apart along the length of the channel 120.

[0093] In some embodiments, each region promoting cavitation may extend along a portion of the channel length to a distance between approximately 10% and 400% of the inner diameter of channel 120, optionally between approximately 30% and 300%, optionally between approximately 50% and 200%. In some embodiments, the distance between adjacent regions promoting cavitation may be (e.g.) about 2 to 50 times, about 5 to 30 times, or about 10 to 20 times larger than the inner diameter of channel 120.

[0094] refer to Figures 3A to 3G The diagram shows a section of the tube 110 of a propulsion device 100 according to some embodiments, with the cavitation process illustrated in a series of figures. The cavitation process is analogous to... Figures 2A to 2F The cavitation process described; however, Figures 3A to 3G The pipe 110 shown also includes one or more mechanisms 330 configured to promote cavitation, bubble nucleation and / or bubble coalescence in one or more regions of the channel 120 when the pressure is reduced.

[0095] refer to Figure 3A Under base pressure, channel 120 can be substantially or completely filled with liquid 130, with little or no gas in channel 120.

[0096] As the pressure in channel 120 is gradually reduced by pressure actuator 140, bubbles 133 can begin to form in the liquid 130 within channel 120, such as Figure 3B As shown. Some bubbles 133 may form randomly throughout the liquid 130; however, the probability of bubble 133 forming will be higher in the region of the cavitation promoting mechanism 330.

[0097] As the pressure decreases further, bubble 133 can grow in volume to form larger bubble 133c, such as Figure 3C As shown, new bubbles 133 can continue to form through nucleation. Some bubbles 133, 133c can coalesce to form even larger bubbles 133d, such as... Figure 3D As shown.

[0098] Bubbles 133 can coalesce to form transcavity bubbles 133e, which span the entire diameter of the inner cavity of channel 120, such as... Figure 3E As shown. Due to the formation of a larger number or size of bubbles and / or enhanced bubble coalescence, it is more likely that transcavity bubbles 133e will form in the region of mechanism 330.

[0099] As the pressure increases, the liquid 130 is accelerated in the distal direction (i.e., toward the first or distal end 122 of channel 120), such as Figure 3F As indicated by arrow 301, bubble 133 is compressed and its volume decreases, as... Figure 3G As shown.

[0100] When bubbles 133 are compressed, they experience a sudden increase in pressure and density and collapse (i.e., dissolve and / or condense) back into liquid 130, as... Figure 3A As shown.

[0101] The apparatus 330 may include any suitable means for enhancing, promoting, facilitating or increasing the likelihood of cavitation, bubble nucleation and / or bubble coalescence.

[0102] refer to Figure 4 In some embodiments, the one or more mechanisms 330 may include variations in the thermal conductivity and / or thermal mass of the tube wall 118 along the length of the channel 120. Such variations in thermal conductivity and / or thermal mass can be achieved by including wall portions 430 at different locations along the length of the channel 120, the wall portions 430 comprising a material having a higher thermal conductivity and / or thermal mass than the remainder of the wall 118. For example, in some embodiments, the wall 118 may be formed from an extruded polymer, and metal particles may be impregnated into certain portions of the wall 118 to create wall portions 430 with relatively high thermal mass and thermal conductivity.

[0103] The difference in thermal conductivity and / or thermal mass between wall portion 430 and the rest of wall 118 can result in a higher likelihood of cavitation and bubble nucleation in the area of ​​wall portion 430 compared to the rest of channel 120.

[0104] In some implementations, the thermal conductivity of wall 118 can be approximately 0.25 W / m along the length of the channel. -1 K -1 Up to 240Wm - 1 K -1 The thermal conductivity varies within a certain range. In some embodiments, the thermal conductivity of the wall portion 430 may be at least 10 times, at least 100 times, at least 500 times, or at least 1000 times higher than that of the rest of the wall 118. For example, in some embodiments, the thermal conductivity of the wall portion 430 may be approximately 100 W / m². -1 K -1 Up to 300Wm -1 K -1 Approximately 150Wm -1 K -1 Up to 250Wm -1 K -1 Or approximately 200Wm -1 K -1 Within a certain range, the thermal conductivity of the remaining portion of wall 118 can be approximately 0.1 W / m². -1 K -1 Up to 10Wm -1 K -1 or approximately 0.5Wm -1 K -1 Up to 1Wm -1 K -1 Within the range.

[0105] refer to Figure 5 In some embodiments, the one or more mechanisms 330 may include one or more acoustic transducers 530. The acoustic transducers 530 may be connected to a controller via one or more cables 535 and are configured to emit acoustic energy with amplitudes and frequencies that promote cavitation, bubble nucleation, and / or bubble coalescence.

[0106] The acoustic transducer 530 can be coupled to the outer or inner surface of the tube 110, disposed outside the wall 118 of the tube 110, or in some embodiments, disposed or embedded within the wall 118 of the tube 110. In some embodiments, the acoustic transducer 530 may include a piezoelectric patch transducer.

[0107] The operating frequency of the acoustic transducer 530 can be, for example, in the range of about 1 kHz to 100 kHz or about 10 kHz to 25 kHz. The operating frequency of the acoustic transducer 530 can be selected to be higher than the Black threshold for mechanical nucleation of at least 1 micrometer bubbles in a system with a gas saturation coefficient close to 1 (i.e., fully saturated). The threshold increases with increasing frequency and decreasing gas saturation (for reference, see Acoustic cavitation prediction, REApfel, The Journal of the Acoustical Society of America 69, p. 1624 (1981)).

[0108] The acoustic wave energy can be directed by the acoustic transducer 530 into the cavity of the channel to promote, enhance, or assist in inducing cavitation in the liquid 130. In some embodiments, the characteristics of the acoustic wave field may include, for example, a pressure change in the range of about 10 MPa to 100 MPa, a pulse duration in the range of about 0.2 ms to 10 ms, and a total power in the range of about 10 mW to 100 mW. In some embodiments, the acoustic transducer 530 can operate at a pressure of about 100 kPa, a displacement of about 25 μm, and a frequency of about 21 kHz.

[0109] In some embodiments, mechanism 330 may include one or more lasers configured to induce cavitation in liquid 130. For example, in some embodiments, mechanism 330 may include a miniature diode laser module embedded in the wall 118 of tube 110. The laser module may be activated with pulses of duration from 10 ms to 20 ms to coincide with the low-pressure phase of a pressure cycle, thereby promoting, enhancing, or aiding in the nucleation of bubbles 133.

[0110] In some embodiments, mechanism 330 may include one or more pairs of electrical conductors disposed within the cavity of channel 120 and arranged at close intervals in the range of about 0.1 mm to 0.5 mm, such that current can be discharged from one conductor to another through liquid 130, thereby causing ionization of liquid 130 and subsequent gas nucleation. The conductive pairs may be arranged in a circular configuration and embedded in the wall of a non-conductive polymer tube. The conductive pairs may be connected to a power source via wires extending along the length of tube 110. The power source may include a high-capacity, high-voltage, low-current discharge circuit that may be timed to discharge at the lowest point of the pressure cycle generated by pressure actuator 140. The supplied voltage may be in the range of about 100 V to 200 V. The current may be in the range of about 1 mA to 10 mA.

[0111] refer to Figure 6In some embodiments, the one or more mechanisms 330 may include a surface variation 630 on the inner surface 126 of the tube 110. That is, the surface variation portion 630 of the inner surface 126 is different from the rest of the inner surface 126 and is configured to promote or induce bubble nucleation.

[0112] In some embodiments, surface change 630 may include a coating applied to a portion of the inner surface 126 of the tube 110. In some embodiments, surface change 630 may include a catalytic material coating, such as octadecyltrichlorosilane (for promoting CO2 nucleation) or other similar compounds. In some embodiments, for example, surface change 630 may include a hydrophobic coating, such as a silane (hydrosilicon) compound, polychloro-p-xylene, or a fluoropolymer, such as PTFE (Teflon). TM Manganese oxide polystyrene (MnO2 / PS), nano-composite zinc oxide polystyrene (ZnO / PS), nano-composite precipitated calcium carbonate or fluorinated acrylate oligomers.

[0113] In some embodiments, the remainder of the inner surface 126 may be formed of or coated with a hydrophilic material, such as a combination of urethane, acrylic acid, polyvinylpyrrolidone (PVP), polyethylene oxide, hydroxyethyl methacrylate, or acrylamide, or another material suitable for preventing bubble nucleation on the remainder of the inner surface 126 (i.e., away from surface change 630).

[0114] In some embodiments, surface variation 630 may include topographic variations. Relatively small topographic variations (e.g., on a length scale of approximately 1 μm to 100 μm) can provide nucleation sites to induce or promote bubble nucleation and growth. For example, topographic variations may include changes in surface roughness, microporous surfaces, scratched or dented surfaces, multiple protrusions, protruding fibers, nanotubes, pits, channels, ridges, fins, depressions, cavities, or other geometric variations. Topographic variations can be formed by, for example, molding, scraping, cutting, knurling, etching, abrasion, or imprinting. In some embodiments, porous particles such as ceramics may be embedded at the inner surface 126 in the wall 118 of the tube 110 to provide nucleation sites.

[0115] In some embodiments, the topographic variation may extend across the entire inner surface 126 of the tube 110. In some embodiments, the tube 110 may be formed with a topographic variation extending across the entire inner surface 126, and then certain portions of the inner surface 126 may be smoothed (e.g., using a polymer coating), leaving exposed / unsmooth portions of the topographic variation to form surface variation 630. For example, the wall 118 of the tube 110 may be formed of a porous material, and then certain portions of the inner surface 126 may be sealed, leaving exposed / unsealed portions of the inner surface 126 to form surface variation 630.

[0116] For a given application, surface variation 630 can include any suitable terrain variation. Some suitable terrain variations are described below.

[0117] In some implementations, topographic changes can define multiple V-shaped channels. These V-shaped channels can be aligned parallel to each other, or they can be randomly oriented and intersect each other.

[0118] The characteristic angle of the V-shaped channel (i.e., the angle of the apex of the V-shape) can be, for example, in the range of about 10° to 90°, about 30° to 60°, or about 40° to 50°. The average width of the V-shaped channel can be, for example, in the range of about 1 μm to 10 μm or about 2 μm to 4 μm. The average depth of the V-shaped channel can be, for example, in the range of about 1 μm to 10 μm or about 2 μm to 4 μm.

[0119] refer to Figure 7 In some embodiments, the surface variation 730 may include a partially randomized pattern of intersecting V-shaped channels 737. This can be achieved by abrasion using diamond particles with a nominal size of 2 μm. The diamond particles may have sharp V-shaped apexes and may be sintered onto a metal rod for rotational application to the inner surface 126. The metal rod can be applied to the inner surface 126 by rotational oscillation to produce the surface variation 730. Atomic force micrographs of typical random V-shaped scratch patterns obtained using this method are shown in... Figure 7 As shown in the image.

[0120] In some implementations, topographic changes can define multiple cone-shaped depressions. These cone-shaped depressions can be arranged randomly or in a periodic array.

[0121] The characteristic angle of the conical pit (i.e., the angle of the apex of the conical pit) can be in the range of, for example, about 10° to 90°, about 30° to 60°, or about 40° to 50°. The average width of the conical pit can be in the range of, for example, about 1 μm to 10 μm or about 2 μm to 4 μm. The average depth of the conical pit can be in the range of, for example, about 1 μm to 10 μm or about 2 μm to 4 μm.

[0122] In some implementations, topographic changes can define multiple protrusions. Protrusions can define any suitable shape, and in some implementations, multiple different shapes can be defined. Protrusions can be arranged randomly or in a periodic array.

[0123] The average height of the protrusions can range, for example, from about 0.1 μm to 1 mm, from about 1 μm to 500 μm, or from about 10 μm to 100 μm. The average width of the protrusions can range, for example, from about 0.1 μm to 500 μm, from about 0.5 μm to 100 μm, or from about 1 μm to 10 μm. The average distance between adjacent protrusions can range, for example, from about 0.1 μm to 500 μm, from about 0.5 μm to 100 μm, or from about 1 μm to 10 μm.

[0124] refer to Figures 8A to 8E The diagram illustrates some examples of surface variations 830 according to some embodiments. Each surface variation 830 defines a plurality of protrusions 835. In some embodiments, the protrusions 835 may define fins or ridges 835 separated by channels 837.

[0125] In some embodiments, the protrusion 835 may comprise nanowires or hollow nanotubes, which may be formed of materials such as carbon or silicon. For nanowires, for example, the width of the protrusion 835 may be in the range of about 10 nm to 500 nm, about 20 nm to 300 nm, or about 100 nm to 200 nm; the length or height of the protrusion 835 may be in the range of about 0.1 μm to 100 μm, about 1 μm to 50 μm, or about 10 μm to 20 μm; and the average spacing between the protrusions 835 may be in the range of about 10 nm to 10 μm, about 10 nm to 100 nm, or about 100 nm to 1 μm. For nanotubes, for example, the width of protrusion 835 can be in the range of about 10 nm to 100 nm, about 10 nm to 50 nm, or about 20 nm to 40 nm; the length or height of protrusion 835 can be in the range of about 1 μm to 50 μm, about 5 μm to 30 μm, or about 10 μm to 20 μm; the pore size (or inner diameter) of protrusion 835 can be in the range of about 1 μm to 40 μm, about 5 μm to 30 μm, or about 10 μm to 20 μm; and the average spacing between protrusions 835 can be in the range of about 10 nm to 10 μm, about 10 nm to 100 nm, or about 100 nm to 1 μm.

[0126] In some implementations, for example, topographical variations can define porous surfaces, such as foams, sintered materials, or other porous materials. The average pore size of the porous surface can range, for example, from about 10 nm to 200 μm, from about 20 nm to 250 nm, from about 50 nm to 150 nm, from about 10 μm to about 200 μm, or from about 50 μm to about 100 μm. The porous surface may include a layer of porous material. The thickness of the porous layer can range, for example, from about 10 μm to 1 mm or from about 50 μm to 100 μm.

[0127] refer to Figure 9 The diagram illustrates a surface variation 930 including a porous layer 933 according to some embodiments. The porous layer 933 may be formed from sintered particles 935 with diameters ranging from, for example, about 10 μm to about 100 μm.

[0128] In some implementations, the terrain variation may have a surface roughness in the range of, for example, about 0.1 μm to 500 μm, about 0.5 μm to 100 μm, or about 1 μm to 10 μm.

[0129] In some embodiments, liquid 13 may contain one or more additives to promote cavitation, bubble nucleation, and / or bubble coalescence. For example, additives may be included to alter the density, viscosity, pH level, gas solubility, coalescence characteristics, or surface tension of liquid 130.

[0130] The solubility and coalescence characteristics of each fluid-gas combination can depend on controllable factors such as temperature and pH. In the case of CO2, the pH of the solution is considered ideally to be adjusted between 6 and 6.5 for optimal results. If the pH is higher than 6.5, bubble nucleation may be difficult to induce due to the high solubility of the gas in water. In some embodiments, when CO2 is used as the gas, the pH of the solution can be lowered to a level between 6 and 6.5 with the addition of acetic acid to promote the nucleation and coalescence of CO2 bubbles in the liquid.

[0131] In some applications, the mechanical work performed by the pressure actuator 140 on the liquid 130 can generate heat in the liquid 130, which can reduce the solubility of gas 133 in the liquid 130. In some embodiments, the propulsion device 100 may include a radiator (not shown) to remove excess heat from the liquid 130. For example, the radiator may include a metal radiator disposed at or near the proximal end 114 of the tube 110, which may be located within or near the pressure actuator 140. The radiator may be cooled by air convection, refrigeration, or radiation.

[0132] In some embodiments, the thermal conductivity of liquid 130 is sufficient to allow heat to be transferred through liquid 130 to the radiator along pipe 110. In some embodiments, a salt such as potassium formate can be added to water to increase the thermal conductivity and density of liquid 130 without significantly increasing viscosity or boiling point.

[0133] In some embodiments, the thermal mass and conductivity of the tube 110 itself may be sufficient to transfer heat along the tube 110 to the radiator. In some embodiments, the tube wall 118 may include one or more thermal conductors, such as a metal film or metal wire, to transfer heat along the tube 110 to the radiator.

[0134] In some embodiments, liquid 130 may include a particularly dense liquid, and / or one or more additives may be included in liquid 130 to increase the density or inertia of liquid 130 in order to increase the momentum generated when liquid 130 accelerates, and thus increase the momentum transferred to tube 110 to advance tube 110 along the passage.

[0135] In some implementations, such as for medical use, liquid 130 may include water in combination with one or more additives, such as: ethanol to reduce surface tension and viscosity; citric acid or acetic acid to reduce pH level; or salts such as sodium chloride to increase density.

[0136] In some embodiments, the inner surface 126 of the tube 110 may define a relatively large-scale topographical change (e.g., a length scale in the range of about 5% to 10% of the inner diameter of the tube 110), which is configured to enhance momentum transfer from the liquid 130 to the tube 110 during a sudden increase in pressure.

[0137] refer to Figures 10A to 10C The diagram illustrates a section of pipe 110 according to some embodiments, showing examples of large-scale topographical variations defined by an inner surface 126. The inner surface 126 may define a plurality of periodic annular ridges 1010 sweeping rearward in a proximal direction (towards the second or proximal end 124 of the channel 120). The ridges 1010 appear in cross-section as a swept fir pattern or proximal swept teeth, such as... Figures 10A to 10C As shown.

[0138] The proximal swept annular ridge 1010 can provide a fluid diode effect, thereby providing greater resistance to fluid flow in the distal direction and relatively less resistance to fluid flow in the proximal direction. This effect can enhance momentum transfer from liquid 130 to pipe 110 during sudden pressure increases.

[0139] In some implementations, the annular ridge 1010 may not sweep proximally, and the fluid diode effect may be achieved using different types of terrain variations, or in some implementations, it may not be achieved at all.

[0140] As described above, when channel 120 contains a certain volume of liquid 130 and an independent volume of gas 133 in an initial or static state, pressure actuator 140 can be configured to increase the channel pressure to dissolve the gas 133 into the liquid 130 (this can be referred to as the pressure increase phase), and subsequently decrease the channel pressure to induce nucleation and cavitation of bubbles 133 in the liquid 130 (this can be referred to as the pressure decrease phase). Alternatively, when channel 120 contains only liquid 130 in an initial or static state, pressure actuator 140 can be configured to decrease the channel pressure to induce nucleation and cavitation of bubbles 133 in the liquid 130 (pressure decrease phase), and subsequently increase the channel pressure to cause the bubbles 133 to collapse into the liquid 130 (by condensation or dissolution) (pressure increase phase).

[0141] In some implementations, the pressure increase phase may be substantially similar in duration to the pressure decrease phase. In other implementations, the duration of the pressure increase phase may be significantly shorter than the duration of the pressure decrease phase.

[0142] In some implementations, the pressure actuator 140 may be configured to increase pressure during a time period, for example, between about 1% and 50% of the time period during which pressure is reduced, optionally between about 5% and 30%, and optionally between about 10% and 20%.

[0143] As described above, the pressure actuator 140 may include any suitable device for changing the channel pressure in the manner described. In some embodiments, the pressure actuator 140 may include a flexible diaphragm with a mechanism configured to deflect or deform the diaphragm to change the volume of the system and control the channel pressure. In some embodiments, the pressure actuator 140 may include a reciprocating piston driven by a motor, such as an electric motor or a linear motor.

[0144] refer to Figure 11 The diagram shows an exemplary displacement distribution x(t) and a corresponding velocity distribution v(t) according to some embodiments, which illustrates the movement of a pressure actuator 140 in the form of a piston over time.

[0145] The displacement and velocity distribution diagram shows the pressure increase phase 1110, followed by the pressure decrease phase 1120. During the pressure increase phase 1110 (corresponding to the piston's compression stroke), the piston experiences rapid acceleration 1112, which is made possible by the highly compressible nature of the bubbles 133.

[0146] Once the bubble 133 collapses back into the liquid 130, a sudden deceleration 1114 occurs in the piston due to the relatively incompressible nature of the liquid 130 (i.e., much less compressible than the gas 133). This sudden deceleration 1114 of the piston and the liquid 130 results in a large impulse and momentum transfer from the liquid 130 to the tube 110 and the resulting propulsive effect, which advances the tube 110 along the passage 103.

[0147] After piston deceleration 1114, once the channel pressure has reached its maximum value, the pressure reduction phase 1120 begins as the piston retracts. Due to the time required for bubble nucleation and cavitation 133, the retraction stroke (pressure reduction phase 1120) may be significantly slower than the compression stroke (pressure increase phase 1110). The channel pressure then decreases to its minimum value. The piston's movement can then be repeated in a similar manner to perpetuate the pressure change cycle.

[0148] The pressure actuator 140 can be configured to repeatedly increase and decrease the channel pressure to impart momentum to the tube 110 with multiple pulses, each pulse associated with a corresponding pressure increase phase. In some embodiments, the channel pressure can be changed by the pressure actuator 140 in a periodic or cyclic manner with repeated pressure cycles (i.e., pressure increases followed by pressure decreases). In some embodiments, the pressure actuator 140 can be configured to change the channel pressure according to repeated pressure cycles, the frequency of which is in the range of, for example, about 0.1 Hz to 10 Hz, about 0.5 Hz to 5 Hz, about 0.5 Hz to 1.5 Hz, about 2 Hz to 4 Hz, or about 3 Hz.

[0149] In some implementations, the pressure actuator 140 can be configured to operate in a reverse cycle to regulate the channel pressure, thereby imparting a reverse pulse to the tube 110 to move the instrument in the proximal direction. This reverse pressure cycle can be used to withdraw the instrument from the passage.

[0150] refer to Figure 12 The diagram illustrates an exemplary pressure / time distribution according to some embodiments, showing the channel pressure changes required to compress bubble 133 into liquid 130 when pressure increases and subsequently induce cavitation of bubble 133 in liquid 130 when pressure decreases. The pressure scale is shown in kilopascals (kPa) above atmospheric pressure, and the time scale is shown in seconds. The channel pressure gradually decreases over a period of approximately 0.3 s and then suddenly increases over a period of approximately 0.05 s. This pressurization cycle repeats at a frequency of approximately 3 Hz.

[0151] As previously discussed, in some embodiments, it may be desirable for the channel 120 to be relatively small in order to increase the likelihood of forming across the bubble 133e prior to compression. The inner diameter of the channel 120 can range, for example, from 0.1 mm to 10 mm, 0.1 mm to 1 mm, 0.1 mm to 0.5 mm, 1 mm to 7 mm, or 2 mm to 5 mm. In some embodiments, the propulsion device 100 may include a plurality of side-by-side extending tubes 110, such as... Figure 13A and Figure 13B The cross-section of the example tube configuration shown is illustrated.

[0152] In some embodiments, tube 110 may be arranged around instrument channel 1301, which is configured to receive probes, such as endoscopes, for example... Figure 13B As shown. In some embodiments, tubes 110 can be bundled together for insertion into the lumen of a probe, such as an endoscope, for example... Figure 13A As shown. In some embodiments, tube 110 may be integrally formed as part of a probe such as an endoscope, wherein instrument channels (e.g., video channels, illumination, flushing, aspiration, manipulation, biopsy, and other instrument channels) extend along tube 110.

[0153] In some embodiments, the propulsion device 100 may include a first tube 110 located within a second tube 110, wherein liquid 130 and gas 133 are contained in an annular channel 120 defined between the two tubes 110. The inner cavity of the first tube 110 may also contain liquid 130 and gas 133, or alternatively, in some embodiments, the inner cavity of the first tube 110 may define an instrument channel.

[0154] The tube 110 or more tubes 110 may be formed of a flexible material with sufficient strength and stiffness to withstand the expected forces of a given application. For medical applications, some suitable materials may include, for example, high to ultra-high molecular weight polyethylene or other biocompatible polymers. In some embodiments, for example, the tube 110 or more tubes 110 may be formed of a composite material, such as a polyethylene spiral with a polyurethane and silicone elastomer coating.

[0155] The size of tube 110 can vary for different applications. For example, for medical endoscopes, such as gastrointestinal endoscopes, a single-tube advance device may include a tube 110 with an outer diameter of 8 mm and an inner diameter of 6 mm, or an outer diameter of 6 mm and an inner diameter of 4.5 mm, while a multi-tube advance device may include four tubes 110, each with an outer diameter of 3 mm and an inner diameter of 2 mm. In some embodiments, the tube 110 of the single-tube advance device 100 or the tube 110 of the multi-tube advance device 100 may have an inner diameter in the range of, for example, 1 mm to 5 mm and an outer diameter in the range of, for example, 0.5 mm to 15 mm, 1 mm to 10 mm, 2 mm to 8 mm, or 4 mm to 6 mm. The length of a medical endoscope is typically in the range of, for example, about 1 m to 5 m or about 3 m to 4 m. In some embodiments, such as for gastrointestinal endoscopy, the length of tube 110 can be in the range of, for example, 3m to 4m, 1m to 5m, or even greater than 5m (such as 5m to 15m or 7m to 9m for veterinary applications). In some embodiments, such as for arterial endoscopy, the length of tube can be in the range of, for example, 0.5m to 2m, 0.7m to 1.5m, or 0.9m to 1.2m. In some embodiments, such as for industrial endoscopes, the tube size can be much larger.

[0156] For medical applications, sterility of the propulsion device 100 will generally be important. Therefore, it may be desirable for at least a portion of the device 100 to include disposable components, which can be housed in sterile packaging and discarded after use. (Reference) Figure 14 The diagram illustrates a propulsion device 1400 according to some embodiments. The propulsion device 1400 includes features substantially similar to those described with respect to propulsion device 100 and designated with similar numerals. A pressure actuator 1440 and a proximal end 1414 of a tube 1410 defining a channel 1420 are shown. It should be understood that the tube 1410 extends to a distal end (not shown), as described with respect to… Figure 1 The propulsion device 100 is described. The tube 1410 may be referred to as a propulsion tube and may include features similar to those of the tube 110 described above. In some embodiments, the tube 1410 may include the tube 110, or as described regarding... Figure 13A or Figure 13B The described tube bundle 110.

[0157] The pressure actuator 1440 includes a housing 1442, a drive mechanism 1444 (in the form of a motor), an actuating rod 1446, and a socket 1448 defined in one side of the housing 1442. The pressure actuator 1440 also includes a piston assembly 1450, which includes a body 1452 defining a cylinder 1454, a piston 1456 disposed within the cylinder, and a piston seal 158 sealing the piston 1456 against an inner bore 1460 of the cylinder 1454. The piston 1456 and the cylinder 1454 work together to form a piston pump. However, in some embodiments, different types of pumps or compressors may be used to regulate the channel pressure in the pipe 1410, such as a diaphragm pump, as described below. Figure 17 As described.

[0158] Piston assembly 1450 is attached to tube 1410 to form tube unit 1401. Tube unit 1401 can be manufactured and filled with a predetermined mass of liquid 130 and a predetermined mass of gas 133, which is sealed within channel 1420 of tube 1410 at a predetermined pressure. Tube unit 1401 can then be separately packaged and sterilized from housing 1442 (including socket 1448 and drive mechanism 1444), such that housing 1442 can be resterilized and reused, while tube unit 1401 can be manufactured and sterilized as a disposable unit for disposal after use.

[0159] This arrangement makes it easier to sterilize fluids 130, 133 and tube unit 1401 together, rather than having to fill tube 1410 with sterile fluids 130, 133 in a sterile environment (such as an operating room).

[0160] The piston assembly 1450 is removably coupled to the housing 1442 (i.e., removable from the socket 1448). The socket 1448 may include an internal cylindrical wall 1486 that helps define the socket 1448 and accommodate the piston assembly 1450 within the socket 1448.

[0161] Body 1452 defines a first opening 1462 and a second opening 1464, wherein cylinder 1454 defines an open passage between the first opening 1462 and the second opening 1464. The proximal end 1414 of tube 1410 is connected to body 1452 of piston assembly 1450 at the second opening 1464, such that passage 1420 is in fluid communication with cylinder 1454. The inner diameter or orifice of cylinder 1454 can be significantly larger than the inner diameter of tube 1410, requiring a relatively short stroke length to influence the desired pressure change in tube 1410. For example, the ratio of the inner diameter of tube 1410 to that of cylinder 1454 can be in the range of 0.01 to 0.5, 0.05 to 0.4, 0.1 to 0.3, or 0.1 to 0.2.

[0162] The inner diameter of cylinder 1454 can gradually decrease to the inner diameter of tube 1410 at the second opening 1464. In some embodiments, the second opening 1464 can be offset from the central axis of body 1452, and when pressure actuator 1440 is configured horizontally, the second opening 1464 can be located at or near the top of cylinder 1454. This reduces the likelihood that bubbles that may form in cylinder 1454 during cavitation will be trapped in the cylinder, and instead allows bubbles to rise towards the second opening 1464 and enter tube 1410 due to gravity.

[0163] The pressure actuator 1440 is configured to move the piston 1456 back and forth along the length of the cylinder 1454 to regulate the channel pressure, such as by changing the channel pressure in the pipe 1410. A compression stroke or pressure-increasing stroke moves the piston 1456 toward the pipe 1410 and pushes fluid from the cylinder 1454 into the pipe 1410, thereby increasing the channel pressure in the pipe 1410. A return stroke, retraction stroke, or pressure-decreasing stroke moves the piston 1456 away from the pipe 1410 and allows fluid to flow back from the pipe 1410 to the cylinder 1454, thereby decreasing the channel pressure in the pipe 1410.

[0164] A motor 1444 and an actuator rod 1446 are disposed within a housing 1442 such that when the piston assembly 1450 is disposed in a socket 1448, the actuator rod 1446 is aligned with a first opening 1462 of the body 1452 and can pass through the first opening 1462 to contact the piston 1456 and move the piston 1456 within the cylinder 1454. In some embodiments, when the actuator rod 1446 is retracted from the cylinder 1454, the channel pressure within the tube 1410 may be sufficient to move the piston 1456 through the return stroke. In some embodiments, the piston assembly 1450 may further include a biasing member 1470, such as a spring, to bias the piston 1456 against the actuator rod 1446 and / or away from the tube 1410 such that when the actuator rod 1446 is retracted from the cylinder 1454, the piston 1456 is pushed back by the biasing member 1470 through the return stroke. For example, the biasing member 1470 may include a stainless steel spring and / or a coil spring. In some implementations, the actuator 1446 may be removably coupled to the piston 1456 itself to allow the actuator 1446 to pull the piston 1456 backward and push the piston 1456 forward.

[0165] The piston assembly 1450 may also include a locking ring 1466 to restrict the piston 1456 from being removed from the cylinder 1454 through the first opening 1462. In some embodiments, the drive mechanism 1444 may include one or more electromagnets configured to drive the piston 1456 directly instead of via a motor and an actuator rod.

[0166] The body 1452 may also define one or more locking lugs 1468 configured to engage a socket 1448 to couple the piston assembly 1450 to the housing 1442. The socket 1448 may also include one or more external flanges 1488 configured to engage the lugs 1468 to secure the piston assembly 1450 within the socket 1448. In this manner, the piston assembly 1450 is configured to be removably coupled to the housing 1442, such that the piston assembly 1450 and the tube 1410 can be manufactured together as a single disposable tube unit, while the housing 1442 and the motor 1444 can be reused with a new tube unit for each new operation. For example, the locking lug 1468 may alternatively be referred to as a tab or radial protrusion.

[0167] The tube unit can be assembled with liquid 130 and gas 133 disposed in channel 1420 (at atmospheric pressure or higher, depending on the application) and connected to piston assembly 1450 to seal liquid 130 and gas 133 within the tube unit. In some embodiments, body 1452 can be secured to proximal end 1414 of tube 1410, and piston 1456 is subsequently placed in cylinder 1454 and locked using locking ring 1466 to seal liquid 130 and gas 133 in channel 1420 and cylinder 1454. Seal 1458 may include one or more gaskets, such as O-rings, which may be located in one or more corresponding gasket seats defined in piston 1456, or alternatively in the inner surface of cylinder 1454.

[0168] In some embodiments, the body 1452 of the piston assembly 1450 may include an inlet valve 1490 for filling the passage 1420 of the cylinder 1454 and the pipe 1410 with a predetermined mass of selected liquid 130 and a predetermined mass of selected gas 133. The body 1452 may also include an outlet valve 1492 to allow air to be released from the passage 1420 and the cylinder 1454 while the passage 1420 and the cylinder 1454 are being filled with liquid 130 and gas 133.

[0169] Valves 1490 and 1492 may be located at one end of the body 1452 near the second opening and may be configured to maintain pressure within cylinder 1454 and passage 1420. In some embodiments, valves 1490 and 1492 may comprise spring-loaded piston valves. Inlet valve 1490 may be located relatively close to the second opening 1464, and outlet valve 1492 may be located relatively far from the second opening 1464, such as... Figure 14 As shown.

[0170] To fill tube unit 1401 with gas 133 and liquid 130, body 1452 can be held inverted, or arranged such that valves 1490, 1492 are positioned above the second opening, with most or substantially all of the volume of passage 1420 and cylinder 1454 below the level of outlet valve 1492. This is to cause excess air to rise toward outlet valve 1492 when passage 1420 and cylinder 1454 are being filled with liquid 130. Air can be drawn from outlet valve 1492 via vacuum lines or other suction devices.

[0171] In some cases, liquid 130 and gas 133 can be mixed together in a pressure vessel such that gas 133 is completely dissolved in liquid 130 to form a saturated solution. In this case, as air is removed via outlet valve 1492, the gas / liquid solution can be introduced into pipe unit 1401 via inlet valve 1490. If gas 133 and liquid 130 are to be introduced separately, it may be preferable to first remove as much air as possible from passage 1420 and cylinder 1454 via outlet valve 1492; before injecting liquid 130 into passage 1420 and cylinder 1454 via inlet valve 1490; remove any remaining air via outlet valve 1492; and then inject gas 133 into passage 1420 and cylinder 1454 via inlet valve 1492.

[0172] Alternatively, tube 1410 may be formed with an open distal end; as air is drawn from cylinder 1454, liquid 130 and gas 133 may be drawn along channel 1420 and into cylinder 1454; and the distal end of tube 1410 may then be sealed with a plug and a steel mold to retain the plug in channel 1420 and seal tube 1410. However, it may be preferable to form tube 1410 with a closed distal end to avoid the need to seal it with a plug or other means.

[0173] Once the tubing unit is fully assembled with the liquid 130 and gas 133 sealed within the channel 1420 and cylinder 1454, the tubing unit can be encapsulated and sterilized using gamma radiation, for example. The tube 1410 and piston assembly 1450 together define a sealed container holding a selected mass of liquid 130 and a selected mass of gas 133. In some embodiments, an hermetically sealed closure can be fitted onto the body 1452 of the piston assembly 1450 during encapsulation to close the first opening 1462 of the cylinder 1454 and help maintain the pressure of the selected tubing channel before use. The body 1452 may include an engagement portion (not shown) that defines one or more recesses, notches, or protrusions to engage the closure and form a hermetically sealed seal.

[0174] In some implementations, the pressure actuator 1440 may include a diaphragm pump instead of a piston pump to control the channel pressure in pipe 1410. (Reference) Figure 17The propulsion device 1400 is shown with an alternative tube unit 1701, which includes a diaphragm pump assembly 1750 instead of the piston assembly 1450 described above. In all other respects, the tube unit 1701 may be substantially similar to the tube unit 1401 described above, wherein similar features are indicated by the same reference numerals.

[0175] The diaphragm pump assembly 1750 includes a body 1752 and a diaphragm 1770. The body 1752 defines a chamber 1754 extending between a first opening 1762 and a second opening 1764. The diaphragm 1770 closes or covers the first opening 1762 of the chamber 1754. A proximal end portion 1414 of a tube 1410 is connected to the body 1752 of the diaphragm pump assembly 1750 at the second opening 1764, such that a passage 1420 is in fluid communication with the chamber 1754. The body 1752 may also define one or more lugs 1768 configured to engage a flange 1488 of a socket 1448 to couple the diaphragm pump assembly 1750 to a housing 1442.

[0176] In some embodiments, the body 1752 of the diaphragm pump assembly 1750 may include an inlet valve 1790 and an outlet valve 1792, which may be configured in a manner similar to the valves 1490 and 1492 described with respect to the pipe unit 1401 and the body 1452.

[0177] The diaphragm 1770 can be formed separately and held in place above the first opening 1762 of the chamber 1754 by a clamp 1772. For example, the clamp 1772 may include a threaded locking ring configured to thread-engage the body 1752, thereby clamping the periphery of the diaphragm 1770 between the body 1752 and the clamp 1772, as shown. Figure 17 As shown. In other embodiments, the diaphragm 1770 may be integrally formed with the body 1752, for example, using a composite molding process.

[0178] The diaphragm 1770 includes an elastically deformable membrane that can be deformed by an actuator to change the volume of a chamber 1754 in fluid communication with the channel 1420 of the tube 1410. A central portion 1774 of the diaphragm 1770 can be removably coupled to an actuating rod 1446 of a drive mechanism 1444. The diaphragm 1770 includes an elastically deformable portion 1776 surrounding the central portion 1774, allowing the central portion 1774 to move back and forth relative to the body 1752 along an axis 1780 substantially orthogonal (perpendicular) to the surface of the central portion 1774. For example, parallel or aligned with the axial movement of the actuating rod 1446 of the drive mechanism or linear motor 1444.

[0179] As the central portion 1774 of the diaphragm 1770 moves back and forth between the compressed position 1778a (shown in dashed lines) and the retracted position 1778b (shown in solid lines), the volume of the chamber 1754 changes. Therefore, the channel pressure in the tube 1410 can be adjusted and controlled by controlling the position of the actuator rod 1446 and the central portion 1774 of the diaphragm 1770.

[0180] The diaphragm 1770 can be circular or rotationally symmetrical, but can be defined by any suitable shape for an elastically deformable membrane. Chamber 1754 in Figure 17 The chamber is shown as a cylinder, but any suitable shape can be defined to provide the desired range of channel pressure. In some embodiments, the chamber 1754 may be relatively short and taper towards the second end 1764, thereby allowing for a relatively wide diaphragm 1770 and a relatively narrow diameter of the second opening 1764 to allow for a greater range of channel pressures for achieving relatively small axial movement of the diaphragm.

[0181] In some embodiments, different tubing units for different medical applications may be fitted with similar piston assemblies to allow each different tubing unit to be used with a common housing 1442 and a motor 1444. In some embodiments, multiple tubes 1410 may be connected to a single piston assembly 1450, wherein a channel 1420 of each tube 1410 is in fluid communication with a cylinder 1454 of the piston assembly 1450.

[0182] In some implementations, housing 1442 may include a drive console or drive unit 1500, such as Figure 15 As shown. The drive console 1500 may include a power switch 1502 to control the power supply from the power supply 1560 to the drive console 1500.

[0183] The socket 1448 may include one or more circumferential flanges 1488 extending around a circumferential portion of the socket and radially inward to retain the lug 1468 of the body 1452 within the socket 1448. The lug 1468... Figure 15 The lug 1468, shown in dashed lines, projects radially away from the body 1452 to be received within or below the flange 1488. The lug 1468 also extends circumferentially around a portion of the body 1452.

[0184] Both lug 1468 and flange 1488 are arranged such that when piston assembly 1450 is coupled to or disengaged from socket 1448, there is a gap between flange 1488 to allow lug 1468 to pass through, and a gap between lug 1468 to allow flange 1488 to pass through. To couple piston assembly 1450 to housing 1442, body 1452 is inserted into socket 1448, aligning the gap between lug 1468 and flange 1488, and then body 1452 is rotated to engage lug 1468 in a sliding fit within the space defined between flange 1488 and a surface of housing 1442 (not shown) opposite to and directly below flange 1488.

[0185] In some embodiments, lug 1468 and / or flange 1488 may include a resilient latch, clip, or latch to secure body 1452 and prevent rotation during engagement alignment of lug 1468 and flange 1488. Lug 1468 and / or flange 1488 may also include a stop to limit rotation of piston assembly 1450 beyond the angle at which lug 1468 and flange 1488 are fully engaged.

[0186] To detach the piston assembly 1450 from the housing 1442, the body 1450 is rotated to separate the lug 1468 from the flange 1488, wherein the gap between the lug 1468 and the flange 1488 is aligned. The piston assembly 1450 can then be removed from the socket 1448.

[0187] In some embodiments, the body 1450 may include an indicator protrusion 1480 to indicate correct orientation when the piston assembly 1450 is coupled to the socket 1448. A flange 1488 may define complementary cutouts or recesses 1482 configured to allow the indicator protrusion 1480 to pass through when the piston assembly 1450 is correctly oriented for insertion into the socket 1448. Once inserted into the socket 1448, the body 1450 may be rotated, with the indicator protrusion passing beneath one or more of the flanges 1488 until the lug 1468 is fully engaged with the flange 1488. In some embodiments, the housing 1442 may include markings or labels to indicate the position of the indicator protrusion 1480 when the lug 1468 is fully engaged with the flange 1488.

[0188] The drive console 1500 may include a connection indicator light 1504 configured to illuminate when the piston assembly 1450 is connected to the drive console 1500. The drive console 1500 may include a sensor (not shown) to detect when the piston assembly 1450 is connected to the socket 1448 and / or when the lug 1468 is fully engaged with the flange 1488. When the sensor detects that the piston assembly 1450 is connected to the drive console 1500, it may trigger a signal or completion circuit to turn on the connection indicator light 1504.

[0189] The drive control console may include an operation indicator or run indicator 1506, which is configured to illuminate when the pressure actuator 1440 is operated. Indicator 1506 may be included in or linked to circuitry controlling power supply to the motor 1444, such that indicator 1506 is activated when the motor 1444 is operated.

[0190] In some embodiments, the drive console 1500 may include a connection terminal 1508 configured to receive a connector for a signal cable from an external controller (such as a foot switch) for controlling the operation of the pressure actuator 1440. In some embodiments, the drive console 1500 may include a display or user interface 1510 to provide a user with information about the operation of the propulsion device 1400 and / or allow the user to control the operation of the propulsion device 1400. In some embodiments, the drive console 1500 may include a computer and / or controller 1550 configured to control the operation of the propulsion device 1400.

[0191] Computer 1550 can be connected to user interface 1510 to provide information about the operation of propulsion device 1400, and in some embodiments, it can receive input from the user interface to select certain operating parameters. User interface 1510 may include an intelligent display graphical user interface, and computer 1550 may include a programmable microprocessor to control the functions of drive console 1500 and drive mechanism 1444. Power supply 1560 can be connected to drive console 1500 and computer 1550, and computer 1550 can control the power supply to various components of drive console 1500.

[0192] refer to Figure 16The image shows an endoscope system 1600 according to some embodiments. The endoscope system 1600 includes an endoscope 1601 having an insertion tube 1610 for insertion into a patient; an endoscope control console 1620 for controlling the operation of the endoscope; an endoscope handheld device 1630 for further and / or alternative control of the operation of the endoscope 1601; a propulsion device 1400 for advancing the endoscope 1601 and the insertion tube 1610 along a pathway within the patient; and a power source (not shown) for supplying power to the drive console 1500 and the endoscope control console 1620.

[0193] The propulsion device 1400 includes, as described above, a propulsion tube 1410 for insertion into the insertion tube 1610 and a drive control console 1500 for controlling the operation of the propulsion device 1400.

[0194] The endoscope system 1600 may also include a monitor 1640 configured to display images received from the endoscope's camera via the endoscope console 1620.

[0195] As described above, the propulsion device 1400 can be operated to provide propulsion to the endoscope 1601 and the insertion tube 1610 via momentum transfer in the propulsion tube 1410. The propulsion force can be used to advance the endoscope 1601, the insertion tube 1610, and the propulsion tube 1410 along a pathway within the patient's body.

[0196] Because momentum is transferred along the length of the propulsion tube 1410, the risk of the insertion tube 1610 becoming stuck or the resistance is reduced when it passes through bends in the passage (e.g., bends in the gastrointestinal tract), a risk or resistance that often occurs in conventional push-type endoscopes. This propulsion method also reduces friction at each bend as the endoscope advances along the passage, as it provides an alternative to simply pushing the endoscope against each bend to advance it further (as is done with conventional push-type endoscopes).

[0197] In some embodiments, the propulsion device 1400 may be able to advance the endoscope 1601 along the pathway at, for example, an advance speed of about 1.5 cm / s. Depending on various operating environments, conditions, and / or requirements, the advance speed may vary from, for example, from 0.1 cm / s to 2 cm / s or from 0.5 cm / s to 1 cm / s. In some applications, the time-pressure distribution map may be inverted to move the tube 1410 backward along the pathway, for example, to assist in withdrawing the tube 1410 from the pathway. The propulsion device 1400 may also allow for improved completion rates of enteroendoscopy by allowing the endoscope 1601 to advance further or completely along the length of the intestine to allow examination of the entire range of the small intestine. The propulsion device 1400 may also allow access to the entire gastrointestinal tract via endoscopy.

[0198] In various embodiments, propulsion devices 100, 1400, and 1700 can be configured to advance any one or more of the following along a pathway: for example, instruments, probes, sensors, cameras, monitoring devices, tools, surgical instruments, mining tools, drilling tools, endoscopes, colonoscopes, duodenoscopes, tubing endoscopes, robotic tethers, and industrial endoscopes. Propulsion devices 100, 1400, and 1700 can be configured to assist in advancing instruments, sensors, or tools along any one or more of the following: pathways, mine shafts, well shafts, pipes, sewers, cavities, and pathways within a patient's body, such as biological pathways, the lumen of arteries, or tubes.

[0199] Those skilled in the art will understand that various changes and / or modifications can be made to the above embodiments without departing from the broad overall scope of this disclosure. Therefore, this embodiment should be considered illustrative rather than restrictive in all respects.

Claims

1. A propulsion device for advancing an instrument along a path, the propulsion device comprising: An elongated tube includes a first end and a second end opposite to the first end, the tube defining a channel configured to contain liquid, the first end of the channel being closed at or near the first end of the tube, and the second end of the channel being defined by the second end of the tube; as well as A pressure actuator, which communicates with the second end of the channel, is configured to selectively regulate the pressure of the liquid in the channel to alternately: The pressure is reduced to induce cavitation and form bubbles in the liquid; as well as The pressure is increased to cause some or all of the bubbles to collapse back into the liquid, thereby accelerating at least a portion of the liquid toward the first end of the tube and transferring momentum to the tube to advance the tube along the passage. The propulsion device further includes one or more mechanisms configured to promote cavitation in one or more regions of the channel when the pressure decreases, wherein the one or more regions extend along at least a portion of the length of the channel.

2. The propulsion device of claim 1, wherein the one or more mechanisms are configured to facilitate cavitation in a plurality of regions spaced apart along at least a portion of the length of the channel.

3. The propulsion device according to claim 2, wherein one or more mechanisms include surface variations on the inner surface of the channel.

4. The propulsion device according to claim 3, wherein the surface change includes a coating.

5. The propulsion device according to claim 4, wherein the coating comprises a hydrophobic material.

6. The propulsion device according to claim 4, wherein the coating comprises a catalytic material.

7. The propulsion device according to claim 4, wherein the coating comprises one or more coatings selected from the group consisting of: octadecyltrichlorosilane, silane compounds, polychloro-p-xylene, fluoropolymers, PTFE (Teflon) TM Combinations of manganese oxide polystyrene (MnO2 / PS), nano-composite zinc oxide polystyrene (ZnO / PS), nano-composite precipitated calcium carbonate, fluorinated acrylate oligomers, polyurethane, acrylic acid, polyvinylpyrrolidone (PVP), polyethylene oxide, hydroxyethyl methacrylate and acrylamide.

8. The propulsion device according to claim 4, wherein the surface change includes terrain change.

9. The propulsion device according to claim 8, wherein the terrain variation includes a scratched or dented surface.

10. The propulsion device according to claim 8, wherein the terrain change defines a plurality of V-shaped channels.

11. The propulsion device according to claim 10, wherein the characteristic angle of the V-shaped channel is in the range of about 10° to 90°.

12. The propulsion device according to claim 10, wherein the average width of the V-shaped channel is in the range of about 1 μm to 10 μm.

13. The propulsion device according to claim 8, wherein the terrain change defines a plurality of conical depressions.

14. The propulsion device according to claim 13, wherein the characteristic angle of the conical recess is in the range of about 10° to 90°.

15. The propulsion device according to claim 13, wherein the average width of the conical recess is in the range of about 1 μm to 10 μm.

16. The propulsion device of claim 8, wherein the terrain change defines a plurality of protrusions.

17. The propulsion device according to claim 16, wherein the average height of the protrusion is in the range of about 0.1 μm to 1 mm.

18. The propulsion device according to claim 16, wherein the average width of the protrusion is in the range of about 0.1 μm to 500 μm.

19. The propulsion device according to claim 16, wherein the average distance between adjacent protrusions is in the range of about 0.1 μm to 500 μm.

20. The propulsion device according to claim 8, wherein the terrain variation has a surface roughness in the range of about 0.1 μm to 500 μm.

21. The propulsion device according to claim 8, wherein the terrain change defines the porous surface.

22. The propulsion device according to claim 21, wherein the average pore size of the porous surface is in the range of about 10 nm to 200 μm.

23. The propulsion device of claim 1, wherein one or more mechanisms include a variation in the thermal conductivity of the tube wall along the length of the channel.

24. The propulsion device of claim 23, wherein the thermal conductivity of the wall along the length of the channel is approximately 0.25 W / m. -1 K -1 It varies within the range of 240Wm⁻¹K⁻¹.

25. The propulsion device of claim 1, wherein the one or more mechanisms comprise one or more acoustic transducers.

26. The propulsion device according to claim 25, wherein one or more of the acoustic transducers are disposed within the wall of the tube.

27. The propulsion device of claim 25, wherein one or more of the acoustic transducers are disposed outside the wall of the tube.

28. The propulsion device of claim 25, wherein the operating frequency of the acoustic transducer is in the range of about 1 kHz to 100 kHz.

29. The propulsion device of claim 25, wherein the power associated with the acoustic wave energy directed by the acoustic transducer into the cavity of the channel is in the range of about 10mW to 100mW.

30. The propulsion device according to claim 1, wherein the device is configured to advance a medical instrument along an internal cavity within a patient's body.

31. The propulsion device according to claim 1, wherein the channel is a continuous closed channel extending from the first end of the tube to the second end of the tube.

32. The propulsion device according to claim 1, wherein the tube is reinforced to prevent expansion or contraction due to changes in internal pressure.

33. The propulsion device according to claim 1, wherein the tube is formed of a material suitable for sterilization.

34. The propulsion device according to claim 1, further comprising a plurality of said tubes extending side by side.

35. The propulsion device according to any one of claims 1 to 34, wherein the pressure actuator comprises a flexible membrane defining a sealed chamber and a drive mechanism configured to deform the flexible membrane to selectively adjust the pressure of the liquid in the channel.

36. The propulsion device according to any one of claims 1 to 34, wherein the pressure actuator comprises: A piston assembly, comprising a movable piston disposed within a bore in the piston assembly; as well as A drive mechanism configured to drive the piston of the piston assembly to selectively regulate the pressure of the liquid in the channel.

37. The propulsion device of claim 36, wherein the piston assembly is connected to the tube to form a sealed tube unit containing the liquid, and The piston assembly is removably coupled to the drive mechanism.

38. A propulsion tube unit, comprising: One or more tubes according to any one of claims 1 to 34; as well as A piston assembly connected to the second end of the tube, the piston assembly comprising: The body, which defines an orifice in fluid communication with the channel of each of the one or more tubes; and A movable piston is disposed within the bore and configured to seal against the inner surface of the bore. The piston assembly is configured to cooperate with an actuator to move the piston, thereby selectively regulating the pressure of the liquid in the channel to alternately: Reducing the pressure to induce cavitation and form bubbles in the liquid; and The pressure is increased to cause some or all of the bubbles to collapse back into the liquid, thereby accelerating at least a portion of the liquid toward the first end of the tube and transferring momentum to the tube to advance the tube along the passage.

39. The propulsion tube unit of claim 38, wherein the piston assembly and the one or more tubes cooperate to define a sealed container containing a selected mass of liquid and a selected mass of gas.

40. A propulsion tube unit, comprising: One of the tubes according to any one of claims 1 to 34; as well as A movable piston is disposed within the channel at or near the second end of the tube and configured to seal against the inner surface of the channel. The piston is configured to cooperate with an actuator to move the piston, thereby selectively regulating the pressure of the liquid in the channel alternately: The pressure is reduced to induce cavitation and form bubbles in the liquid; as well as The pressure is increased to cause some or all of the bubbles to collapse back into the liquid, thereby accelerating at least a portion of the liquid toward the first end of the tube and transferring momentum to the tube to advance the tube along the passage.

41. The propulsion tube unit of claim 40, wherein the piston and the tube cooperate to define a sealed container containing a selected mass of liquid and a selected mass of gas.

42. A propulsion tube unit, comprising: An elongated tube includes a first end and a second end opposite to the first end, the tube defining a channel configured to contain liquid, the first end of the channel being closed at or near the first end of the tube, and the second end of the channel being defined by the second end of the tube; as well as A piston assembly connected to the second end of the tube, the piston assembly comprising: The body, which defines an orifice in fluid communication with the channel of the tube; and A movable piston is disposed within the bore and configured to seal against the inner surface of the bore. The piston assembly and the tube cooperate to define a sealed container holding a selected mass of liquid and a selected mass of gas. The piston assembly is configured to cooperate with an actuator to move the piston, thereby selectively regulating the pressure of the liquid in the channel to alternately: Reducing the pressure to induce cavitation and form bubbles in the liquid; and The pressure is increased to cause some or all of the bubbles to collapse back into the liquid, thereby accelerating at least a portion of the liquid toward the first end of the tube and transferring momentum to the tube to propel it along the passage.

43. The propulsion tube unit of claim 42, further comprising one or more mechanisms configured to promote cavitation in a plurality of regions spaced apart along at least a portion of the length of the channel when the pressure decreases.

44. The propulsion tube unit of claim 42 or 43, wherein the tube defines a plurality of channels, each channel being configured to contain liquid, a first end of each channel being closed at or near the first end of the tube, and a second end of each channel being defined by the second end of the tube, and The plurality of channels are in fluid communication with each other and with the orifices of the piston assembly.

45. A driver console, comprising: The housing defines the socket, which is configured to receive and engage. The propulsion tube unit according to any one of claims 38 to 44; An actuator configured to engage the piston; as well as A controller configured to operate the actuator to move the piston, thereby selectively regulating the pressure within the channel of the tube to alternately: The pressure is reduced to induce cavitation and form bubbles in the liquid; as well as The pressure is increased to cause some or all of the bubbles to collapse back into the liquid, thereby accelerating at least a portion of the liquid toward the first end of the tube and transferring momentum to the tube to advance the tube along the passage.

46. ​​A method for advancing an instrument along a pathway, which does not include methods for diagnosing or treating diseases, nor does it include surgical methods for non-therapeutic purposes, wherein, The instrument does not include surgical instruments and endoscopes for medical use, and the access does not include access within the patient's body. The method includes selectively adjusting the pressure of a liquid within a tube connected to the instrument to continuously induce cavitation of bubbles in the liquid and subsequently causing the bubbles to collapse back into the liquid to accelerate the liquid within the tube, transferring momentum from the liquid to the tube, and advancing the tube along the access.

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