Peristaltically Self-propelled endoscopic device

• US 20030065250A1
• Filed: 05/08/2002
• Published: 04/03/2003
• Est. Priority Date: 09/17/2001
• Status: Active Grant

• Current Assignee: Case Western Reserve University
• Original Assignee: Case Western Reserve University
• Inventors: Beer, Randall D., Chiel, Hillel J., Mangan, Elizabeth V., Quinn, Roger D.
• Granted Patent: US 6,764,441 B2
• Time in Patent Office: Days
• US Class Current: 600/115
• CPC Class Codes: A61B 1/00156 using self propulsion
• CPC Class Codes: A61B 1/0058 using shape-memory elements
• CPC Class Codes: A61B 1/015 Control of fluid supply or evacuation
• CPC Class Codes: A61B 34/70 Manipulators specially adapted for use in surgery
• CPC Class Codes: A61B 34/72 Micromanipulators

Abstract

Expandable actuators surround a central conduit. Each actuator comprises a bladder that, when fluid is introduced, expands laterally while contracting longitudinally. A restorative spring can be placed inside a bladder and between the two ends to restore the actuator to its original shape as fluid is withdrawn. Multiple actuators can be placed in series to successively inflate and deflate and generate a peristaltic motion. One or more Shape Memory Alloy (SMA) springs can be affixed to one or more restorative springs to cause bending motion.

Claims

1. A self-propelled endoscopic device, comprising:

(a) a flexible conduit having a longitudinal dimension along its length, a lateral dimension at any point along the conduit length that is substantially perpendicular to the longitudinal dimension at that point, and an outer wall;

(b) a first inflatable actuator, the first inflatable actuator;

having a first end in a fixed longitudinal position on the conduit,

having a second end opposing the first end, the second end being slidably attached to the conduit and longitudinally movable along the outer wall, and

being configured to longitudinally contract while laterally expanding during propulsion of the device; and

(c) a second actuator, the second actuator;

having a first end slidably attached to the conduit and longitudinally movable along the outer wall, the first end having at least one point in a substantially fixed position relative to a point on the second end of the first actuator,

having a second end opposing the first end of the second actuator, the second end being slidably attached to the conduit and longitudinally movable along the outer wall, and

being configured to longitudinally contract while laterally expanding.

2. The self-propelled endoscopic device of claim 1, wherein:

the first and second actuators comprise respective first and second bladders,

the first and second bladders are each substantially fluid impermeable,

the first and second bladders comprise respective first and second expansive regions along respective first and second conduit segments, and

the conduit comprises at least one channel for selectively introducing fluid into and withdrawing fluid from the expansive regions.

3. The self-propelled endoscopic device of claim 2, wherein:

the first and second bladders comprise respective outer surfaces,

the respective outer surfaces are flexible and inextensible, and

each bladder expands laterally and contracts longitudinally upon introduction of fluid into the respective expansive region of the bladder.

4. The self-propelled endoscopic device of claim 3, wherein:

the first end of the first bladder is fixedly sealed to the outer wall and a second end of the first bladder is movably sealed to the outer wall, and

the outer surface of the first bladder surrounds the segment of the outer wall between the first and second ends of the first bladder.

5. The self-propelled endoscopic device of claim 4, wherein:

the first actuator further comprises a restoration spring disposed between the first and second ends, and

the restoration spring biases the first and second ends of the away from one another when fluid is withdrawn from the first expansive region.

6. The self-propelled endoscopic device of claim 5, wherein at least one actuator further comprises at least one shape memory alloy spring configured to cause bending of that actuator.

7. The self-propelled endoscopic device of claim 1, wherein at least one of the actuators comprises at least one external protrusion configured to enhance gripping of a substrate by that actuator.

8. The self-propelled endoscopic device of claim 1, further comprising a thermoplastic bearing joining the first and second actuators and movable longitudinally along the outer wall.

9. The self-propelled endoscopic device of claim 4 further comprising a tubular seal comprising a section of flexible fluid-impermeable tubing having two ends, wherein

a first end of the tubular seal is sealed to the outer wall, and

a second end of the tubular seal is sealed to the second end of the first bladder.

10. The self-propelled endoscopic device of claim 2, further comprising a third actuator, the third actuator:

having a first end slidably attached to the conduit and longitudinally movable along the outer wall, the first end having at least one point in a substantially fixed position relative to a point on the second end of the second actuator,

having a second end opposing the first end of the third actuator, the second end being slidably attached to the conduit and longitudinally movable along the outer wall, and

being configured to longitudinally contract while laterally expanding.

11. The self-propelled endoscopic device of claim 2, wherein the endoscope is configured to operate with a gaseous fluid.

12. The self-propelled endoscopic device of claim 2, wherein the endoscope is configured to operate with a liquid fluid.

13. The self-propelled endoscopic device of claim 1, further comprising a third actuator, the third actuator:

having a first end slidably attached to the conduit and longitudinally movable along the outer wall, the first end having at least one point in a substantially fixed position relative to a point on the second end of the second actuator,

having a second end opposing the first end of the third actuator, the second end being slidably attached to the conduit and longitudinally movable along the outer wall, and

being configured to longitudinally contract while laterally expanding.

14. The self-propelled endoscopic device of claim 1, further comprising at least one sensor disposed on an outer surface of an actuator and configured to detect changes in a physically measurable quantity.

15. The self-propelled endoscopic device of claim 14, wherein the physically measurable quantity is at least one of light, pressure, temperature, electrical conductivity, electrical resistance or a chemical characteristic.

16. The self-propelled endoscopic device of claim 1, wherein the conduit further comprises at least one channel configured to deliver fluid to a point external to and near a distal end of the endoscopic device.

17. The self-propelled endoscopic device of claim 1, further comprising at least one manipulating device located at a distal end of the endoscopic device.

18. The self-propelled endoscopic device of claim 1, further comprising a control system having a processor configured:

to receive input signals from a user and from a sensor disposed on or near the surface of an actuator, and

to transmit control signals for laterally expanding at least one of the actuators.

19. The self-propelled endoscopic device of claim 18, wherein the processor is configured to issue control signals for peristaltic propulsion.

20. The self-propelled endoscopic device of claim 19, further comprising at least one electrically-operated fluid control valve, wherein the control signals comprise signals causing the valve to allow fluid travel through the conduit so as to permit inflation and deflation of at least one of the actuators.

21. The self-propelled endoscopic device of claim 20, wherein the processor is further configured to transmit control signals for bending at least one of the actuators.

22. The system of claim 21, wherein the control signals for bending energize a shape memory alloy spring.

23. The self-propelled endoscopic device of claim 20, wherein processor is configured to modify the propulsive motion of the device based on the signals from the at least one sensor.

24. The self-propelled endoscopic device of claim 22, wherein the processor is configured to selectively modify the propulsive motion and bending of the device based on the signals from the at least one sensor.

25. The self-propelled endoscopic device of claim 20, wherein the processor is configured to issue control signals for sequential inflation and deflation of the actuators.

26. The self-propelled endoscopic device of claim 25, wherein the processor is configured to begin inflating one actuator before deflation of an adjacent actuator is complete.

27. The self-propelled endoscopic device of claim 18, wherein the processor is configured to issue the control signals according to an algorithm employing a continuous time recurrent neural network.

28. A self-locomoting machine for probing a confined space, comprising:

a hollow flexible member having a length;

a first McKibben actuator surrounding the flexible member and having opposed first and second ends, the first end being fixed to the hollow member and the second end movable lengthwise along the hollow member; and

a second McKibben actuator surrounding the flexible member, attached to the first McKibben actuator, and having two opposed ends, the two opposed ends of the second McKibben actuator being movable lengthwise along the hollow member.

29. The machine of claim 28, further comprising a third McKibben actuator surrounding the flexible member, attached to the second McKibben actuator, and having two opposed ends, the two opposed ends of the third McKibben actuator being movable lengthwise along the hollow member.

30. The machine of claim 29, wherein each McKibben actuator comprises an internal spring that biases apart the ends of the actuator when internal fluid pressure is reduced.

31. The machine of claim 30, further comprising at least one shape memory alloy spring attached to an internal spring of one of the McKibben actuators and configured to bend that actuator upon being energized.

32. The machine of claim 31, further comprising an automated control system configured to control peristaltic motion of the machine.

33. The machine of claim 32, wherein the control system is further configured to control bending motion of the machine.

34. The machine of claim 32, further comprising a sensor located on an exterior surface of one of the McKibben actuators.

35. The machine of claim 34, wherein the automated control system is further configured to adjust movement of the machine based upon signals from the sensor.