Method and apparatus for instrument propulsion

Abstract

Embodiments generally relate to propulsion tube units and propulsion devices for progressing instruments along passages, and associated methods of use. For example, the instruments may include, tools, sensors, probes and/or monitoring equipment for medical use (such as endoscopy) or industrial use (such as mining). In some embodiments, the propulsion device may comprise an elongate tube defining a channel configured to accommodate a liquid and a pressure actuator in communication with the channel. The pressure actuator may be configured to selectively adjust a pressure of the liquid in the channel to alternatingly: reduce the pressure to induce cavitation and form gas bubbles in the liquid; and increase the pressure to collapse some or all of the gas bubbles back into the liquid, thereby accelerating at least part of the liquid towards the first end of the tube and transferring momentum to the tube to progress the tube along the passage.

1 . A propulsion device for progressing an instrument along a passage, the propulsion device comprising:
 an elongate tube comprising a first end and a second end opposite the first end, the tube defining a channel configured to accommodate a liquid, a first end of the channel being closed at or near the first end of the tube and a second end of the channel being defined by the second end of the tube; and   a pressure actuator in communication with the second end of the channel and configured to selectively adjust a pressure of the liquid in the channel to alternatingly:
 reduce the pressure to induce cavitation and form gas bubbles in the liquid; and 
 increase the pressure to collapse some or all of the gas bubbles back into the liquid, thereby accelerating at least part of the liquid towards the first end of the tube and transferring momentum to the tube to progress the tube along the passage. 
   
     
     
         2 . The propulsion device of  claim 1 , further comprising one or more mechanisms configured to promote cavitation in one or more regions of the channel when the pressure is reduced, wherein the one or more regions extend along at least part of a length of the channel. 
     
     
         3 . The propulsion device of  claim 2 , wherein the one or more mechanisms are configured to promote cavitation in a plurality of regions spaced along at least part of the length of the channel. 
     
     
         4 . The propulsion device of  claim 3 , wherein the one or more mechanisms comprise a surface variation on an internal surface of the channel. 
     
     
         5 . The propulsion device of  claim 4 , wherein the surface variation comprises a coating. 
     
     
         6 . The propulsion device of  claim 5 , wherein the coating comprises a hydrophobic material. 
     
     
         7 . The propulsion device of  claim 5  or  6 , wherein the coating comprises a catalytic material. 
     
     
         8 . The propulsion device of  claim 5 , wherein the coating comprises one or more coatings selected from: octadecyltrichlorosilane, silane compounds, Parylene C, flouropolymers, PTFE (Teflon™), manganese oxide polystyrene (MnO2/PS), nano-composite zinc oxide polystyrene (ZnO/PS), nano-composite precipitated calcium carbonate, fluorinated acrylate oligomers, urethane, acrylic, polyvinylpyrrolidone (PVP), polyethylene oxide, combinations of hydroxyethylmethacrylate, and acrylamides. 
     
     
         9 . The propulsion device of any one of  claims 5  to  8 , wherein the surface variation comprises a topographical variation. 
     
     
         10 . The propulsion device of  claim 9 , wherein the topographical variation comprises a scratched or pitted surface. 
     
     
         11 . The propulsion device of  claim 9  or  10 , wherein the topographical variation defines a plurality of V-shaped channels. 
     
     
         12 . The propulsion device of  claim 11 , wherein a characteristic angle of the V-shaped channels is in the range of about 10° to 90°. 
     
     
         13 . The propulsion device of  claim 11  or  12 , wherein an average width of the V-shaped channels is in the range of about 1 μm to 10 μm. 
     
     
         14 . The propulsion device of any one of  claims 9  to  13 , wherein the topographical variation defines a plurality of conical pits. 
     
     
         15 . The propulsion device of  claim 14 , wherein a characteristic angle of the conical pits is in the range of about 10° to 90°. 
     
     
         16 . The propulsion device of  claim 14  or  15 , wherein an average width of the conical pits is in the range of about 1 μm to 10 μm. 
     
     
         17 . The propulsion device of any one of  claims 9  to  16 , wherein the topographical variation defines a plurality of protrusions. 
     
     
         18 . The propulsion device of  claim 17 , wherein an average height of the protrusions is in the range of about 0.1 μm to 1 mm. 
     
     
         19 . The propulsion device of  claim 17  or  18 , wherein an average width of the protrusions is in the range of about 0.1 μm to 500 μm. 
     
     
         20 . The propulsion device of any one of  claims 17  to  19 , wherein an average distance between adjacent protrusions is in the range of about 0.1 μm to 500 μm. 
     
     
         21 . The propulsion device of any one of  claims 9  to  20 , wherein the topographical variation has a surface roughness in the range of about 0.1 μm to 500 μm. 
     
     
         23 . The propulsion device of any one of  claims 9  to  21 , wherein the topographical variation defines a porous surface. 
     
     
         24 . The propulsion device of  claim 23 , wherein an average pore size of the porous surface is in the range of about 10 nm to 200 μm. 
     
     
         25 . The propulsion device of any one of  claims 2  to  24 , wherein the one or more mechanisms comprise a variation in a thermal conductivity of a wall of the tube along the length of the channel. 
     
     
         26 . The propulsion device of  claim 25 , wherein the thermal conductivity of the wall varies along the length of the channel over a range of about 0.25 Wm −1  K −1  to 240 Wm-1K-1. 
     
     
         27 . The propulsion device of any one of  claims 2  to  26 , wherein the one or more mechanisms comprise one or more acoustic transducers. 
     
     
         28 . The propulsion device of  claim 27 , wherein one or more of the acoustic transducers are disposed within a wall of the tube. 
     
     
         29 . The propulsion device of  claim 27  or  28 , wherein one or more of the acoustic transducers are disposed outside of a wall of the tube. 
     
     
         30 . The propulsion device of any one of  claims 27  to  29 , wherein an operating frequency of the acoustic transducers is in the range of about 1 kHz to 100 kHz. 
     
     
         31 . The propulsion device of any one of  claims 27  to  30 , wherein a power associated with insonation energy directed to a lumen of the channel by the acoustic transducers is in the range of about 10 mW to 100 mW. 
     
     
         32 . The propulsion device of any one of  claims 1  to  31 , wherein the device is configured for progressing a medical instrument along a lumen within a patient. 
     
     
         33 . The propulsion device of any one of  claims 1  to  32 , wherein the channel is a continuous enclosed channel extending from the first end of the tube to the second end of the tube. 
     
     
         34 . The propulsion device of any one of  claims 1  to  33 , wherein the tube is reinforced against expansion or contraction due to internal pressure changes. 
     
     
         35 . The propulsion device of any one of  claims 1  to  34 , wherein the tube is formed of a material suitable for sterilisation. 
     
     
         36 . The propulsion device of any one of  claims 1  to  35 , further comprising a plurality of the tubes of any one of  claims 1  to  31  extending side by side. 
     
     
         37 . The propulsion device of any one of  claims 1  to  36 , wherein the pressure actuator comprises a flexible membrane defining a sealed chamber and a driving mechanism configured to deform the flexible membrane to selectively adjust the pressure of the liquid in the channel. 
     
     
         38 . The propulsion device of any one of  claims 1  to  36 , wherein the pressure actuator comprises:
 a piston assembly including a moveable piston disposed within a bore of the piston assembly; and 
 a driving mechanism configured to drive the piston of the piston assembly to selectively adjust the pressure of the liquid in the channel. 
 
     
     
         39 . The propulsion device of  claim 38 , wherein the piston assembly is connected to the tube to form a sealed tube unit containing the liquid, and
 wherein the piston assembly is removably coupleable to the driving mechanism.   
     
     
         40 . A propulsion tube unit comprising:
 one or more of the tubes according to any one of  claims 1  to  36 ; and   a piston assembly connected to the second end of the tube, the piston assembly comprising:
 a body defining a bore in fluid communication with the channel of each of the one or more tubes; and 
 a movable piston disposed within the bore and configured to seal against an internal surface of the bore. 
   
     
     
         41 . The propulsion tube unit of  claim 40 , wherein the piston assembly and the one or more tubes cooperate to define a sealed vessel containing a selected mass of liquid and a selected mass of gas. 
     
     
         42 . A propulsion tube unit comprising:
 one of the tubes according to any one of  claims 1  to  36 ; and   a movable piston disposed within the channel at or near the second end of the tube and configured to seal against an internal surface of the channel.   
     
     
         43 . The propulsion tube unit of  claim 42 , wherein the piston and the tube cooperate to define a sealed vessel containing a selected mass of liquid and a selected mass of gas. 
     
     
         44 . A propulsion tube unit comprising:
 an elongate tube comprising a first end and a second end opposite the first end, the tube defining a channel configured to accommodate a liquid, a first end of the channel being closed at or near the first end of the tube and a second end of the channel being defined by the second end of the tube; and   a piston assembly connected to the second end of the tube, the piston assembly comprising:
 a body defining a bore in fluid communication with the channel of the tube; and 
 a movable piston disposed within the bore and configured to seal against an internal surface of the bore, 
   wherein the piston assembly and the tube cooperate to define a sealed vessel containing a selected mass of liquid and a selected mass of gas.   
     
     
         45 . A propulsion tube unit according to  claim 44 , wherein the piston assembly is configured for cooperation with an actuator to effect movement of the piston to selectively adjust a pressure of the liquid in the channel to alternatingly:
 reduce the pressure to induce cavitation and form gas bubbles in the liquid; and   increase the pressure to collapse some or all of the gas bubbles back into the liquid, thereby accelerating at least part of the liquid towards the first end of the tube and transferring momentum to the tube to progress the tube along the passage.   
     
     
         46 . A propulsion tube unit according to  claim 44  or  45 , further comprising one or more mechanisms configured to promote cavitation in a plurality of regions spaced along at least part of the length of the channel when the pressure is reduced. 
     
     
         47 . A propulsion tube unit according to any one of  claims 44  to  46 , wherein the tube defines a plurality of channels, each configured to accommodate a 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
 wherein the plurality of channels are all in fluid communication with each other and with the bore of the piston assembly. 
 
     
     
         48 . A drive console comprising:
 a housing defining a socket configured to receive and engage a propulsion tube unit according to any one of  claims 40  to  47 ;   an actuator configured to engage the piston; and   a controller configured to operate the actuator to move the piston to selectively adjust a pressure within the channel of the tube.   
     
     
         49 . A method of progressing an instrument along a passage, the method comprising selectively adjusting a pressure of a liquid within a tube connected to the instrument to successively induce cavitation of gas bubbles in the liquid and subsequently collapse the gas bubbles back into the liquid to accelerate the liquid within the tube, transfer momentum from the liquid to the tube, and progress the tube along the passageway. 
     
     
         50 . The steps, processes, sub-processes, features, integers, structures, components, sub-components, systems, sub-systems, elements, compositions and/or compounds disclosed herein or indicated in the specification of this application individually or collectively, and any and all combinations of two or more of said steps, processes, sub-processes, features, integers, structures, components, sub-components, systems, sub-systems, elements, compositions and/or compounds.