Locomotion Techniques for Robotic Colonoscopy
BY IRWAN KASSIM, LOUIS PHEE, WAN S. NG, FENG GONG, PAOLO DARIO, AND CHARLES A. MOSSE
ancer of the large intestine, also known as colon cancer, develops from the inner lining of the intestine walls and begins with benign polyps. These premalignant growths may eventually increase in size and become cancerous. As the cancer cells multiply, they form a tumor that bulges into the passage of the intestine and blocks movement of stools. The cancer cells can spread to other parts of the body to form new tumors. Low fiber intake, irregular toilet practices, and genetic factors affect the colon, resulting in irritable bowel syndrome, diverticulosis, colorectal cancer, rectal prolapse, hemorrhoids, and inflammatory bowel disease. Symptoms associated with colon cancer are blood in stools, changes in bowel habits, abdominal pain, weight loss, lumps in the abdomen, and bloody mucus discharge. Colon cancer can be treated successfully and even cured if diagnosed early. Unfortunately, many people feel uncomfortable discussing their bowel movements, so they often don’t seek medical attention until it is too late. Colon cancer can affect people at any age; however, the incidence rate rises sharply for those above the age of 50. Therefore, the emphasis is to educate people about colon cancer and the steps to reduce the risk of contracting the disease. One method is to maintain a high-fiber and low-fat diet and another is to be aware of its symptoms. It is encouraged that one should go for a full evaluation of the colon and rectum if any of the symptoms is experienced. This allows abnormalities to be detected early.
C A Literature Review
Conventional Colonoscope
Man has devised many instruments to help him inspect the rectum and colon. In the early 1900s, the first attempts were made with a rigid lighted telescope. With breakthroughs in fiber-optic technology, which allows light and images to be transmitted through curved structures, the first flexible colonoscope and sigmoidoscope were invented in 1963. This allowed an endoscopist to inspect the entire colon and to treat colonic diseases without the need for open surgery. In 1969, Olympus built the first commercial colonoscope [1]. Since then, colonoscopy has become a routine procedure in many hospitals all over the world. The conventional colonoscope consists of three main sections: umbilical cord, control unit, and insertion tube, Figure 1(a). The umbilical cord attaches the scope to the light source. The control unit houses the angulation knob and valves, which control the flipping of the distal end and air/water channel respectively. The insertion tube is the portion of the colonoscope that is IEEE ENGINEERING IN MEDICINE AND BIOLOGY MAGAZINE
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introduced into the patient’s colon via the anus. Running through all the three sections are the wires for a charge-coupled device (CCD) camera, an air/water channel, and fiberoptic bundles for light transmission. The insertion tube, however carries two extra items: the biopsy channel, which allows miniature surgical tools to pass through and control wires that are fixed to the angulation knob to enable flipping the distal end of the scope. At the distal end of the scope, all five items are arranged to sit into a headpiece of about 14 mm in diameter, as shown in Figure 1(b). Apart from just inspecting the colon walls during a colonoscopy, simple operations can be performed by passing miniature surgical tools via the biopsy channel of the scope. Colonoscopy Examination
Colonoscopy is one of the most technically demanding endoscopic examinations and is unpopular with patients. It is an art to coax an almost 2-m-long flexible tube around a tortuous colon while causing minimal discomfort and yet performing a thorough examination. Conventional colonoscopy involves manual insertion and maneuvering of the colonoscope, mainly the insertion tube, by the surgeon. A typical colonoscope is designed to be gripped in the left hand with the left thumb operating the angulation knob to control the flipping of the distal end and the left index finger operating the suction and air/water valves. The right hand is mainly used to advance the insertion tube. Most colonoscopists use similar endoscopic techniques. Air is pumped into the colon to distend it and aid insertion. The insertion pressure on the device must be gentle to avoid stretching the colonic wall, which can cause pain or perforation. The colonoscope is advanced by the pushing action of the endoscopist’s hand under direct vision. A variety of inand-out maneuvers are used to “accordion” the colon on the colonoscope, keeping the colonoscope as free of loops as possible. However, pushing is not the only action involved. Considerable skill is required to pull, wriggle, and shake the colonoscope. The patient’s abdomen may be pressed to minimize looping and discomfort. In a difficult colon, special maneuvers (like reducing the alpha loop in the sigmoid colon) are used to pass the sharply angulated sigmoid/descending colon junction. Torquing of the colonoscope is also required in such a scenario.
The detailed examination of the mucosa is performed both as the colonoscope is introduced and when it is slowly removed from the cecum. If the colonoscope is kept free of loops, the tip responds well and the examination is facilitated. This is especially true if a therapeutic procedure (such as polypectomy) is to be undertaken because large, redundant loops of the colonoscope can make control of the tip very difficult. Drawbacks of Conventional Colonoscopy
The invention of the colonoscope was a quantum leap towards noninvasive surgery. However, there is still room for further improvement as considerable drawbacks, mainly about the manipulation aspect of the procedure, are encountered: ➤ maneuvering difficulty due to manual insertion of the scope ➤ possibility of loop formation of the colonoscope shaft due to external insertion force ➤ demands a high level of expertise and a long training period ➤ the long duration of colonoscopy procedure (average about one half hour) ➤ continuous stress on the hands of the colonoscopist ➤ cumbersome and tedious procedure. Need for Automation
The drawbacks highlighted revolve around the fact that a human being is responsible for the technically demanding task of traversing the colonoscope. These problems may be solved by automating the locomotion aspect of colonoscopy, which has the following advantages: ➤ automatic locomotion of the colonoscope inside the colon ➤ reduction of trauma and discomfort to the patient ➤ ease of training with removal of the manipulative aspect of the procedure ➤ comparable time taken as in manual colonoscopy ➤ facilitatation of massive screening. With automation, the manipulating skills of the surgeon will no longer be the dependent factor. Instead, movement of the colonoscope will be controlled by computers, leading to a faster, more precise, and consistent motion. The endoscopist however, must be present at all times, to guide the machine to do its job. He is still the person who will decide every move the machine makes and to take over when there are uncertainties or in Umbilical case of an emergency. Cord
Air/Water Feeding Button Suction Button
Angulation Knob
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Light Guide Diopter Adjustment Ring Guide
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Fig. 1. The (a) conventional colonoscope and (b) its distal end view displaying the arrangement of the CCD camera, air/water channel, fiber optic bundle and biopsy channel. The control wire is fixed internally onto the headpiece.
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Robotic Colonoscopy
Locomotion is an essential part of robotic colonoscopy. The robot must be able to propel itself from the anus right up to the cecum without damaging the colon walls. The challenge is to design a robust locomotion technique that is able to advance through the stretchable, slippery, and mobile colon, which is always in its collapsed MAY/JUNE 2006
stage, in three-dimensional (3-D) orientation. In addition, it must have the ability to carry optical fibers, surgical tools, and other instruments required in a colonoscopy procedure. A steerable distal end should also be included to flip the robot’s tip, thus allowing the endoscopist to perform a more thorough examination and also position a surgical tool if surgery is required. The problems inherent to pushing a colonoscope through the colon have led to many proposals of providing propulsion at the tip so that the colonoscope can pull itself through the colon or move under natural contraction from the colon wall. On the other hand, there are many lessons to be learned from the animal world. Earthworms, starfish, caterpillars with suction pads on their feet, snakes, millipedes, quadrupeds and squids, or octopuses provide inspiration to imitate their locomotion style. Mechanical means such as wheels and pulleys were also proposed for propelling the endoscope. Earthworm Locomotion
showed that suction alone did not generate sufficient adhesive forces and slipping often occurred. However, it was noted that when a vacuum is introduced, the colon collapses to take the shape of any hard object within. A clamping concept was introduced to compliment the suction, as shown in Figure 2(a). Vacuum is introduced to cause the colon to collapse into the jaws of a mechanical clamp, after which the jaws close to grip onto the trapped tissue. A prototype with suction and clamping was built [Figure 2(b)]. Animal tests have shown that this prototype was capable of propelling itself more than 60 cm into the colon, reaching past the sigmoid colon [7]. Its greatest drawback was what the inventors termed the accordion effect. During the elongation or retraction phases of the inchworm’s locomotion, the colon wall may elongate or retract together with the inchworm; therefore no advancement will take place. A new prototype was designed to overcome this problem [Figure 2(c)]. Suction and a mechanical clamping concept was used; however, the clamps are arranged so that each pair of clamps can slide within each other. In doing so, they would always grasp onto the colon distal to what was previously grasped by the other pair of clamps. This locomotion concept is similar to how a monkey swings from tree to tree. Initial in vivo tests on animals have shown promising results.
The earliest and most common approach to propelling endoscopes is to simulate the way an earthworm moves. By alternately extending and distending sections of their body, an earthworm produces a peristaltic wave that drives it through the Snake Locomotion soil. The simplest earthworm locomotion technique, better Most snake species move by using their ventral scales, the known as inchworm motion, consists of two clampers at its scales on the undersides of their bodies, to pull themselves ends and one extensor at its midsection. The clamper is used to across rough surfaces. Even a paved road has enough rough adhere or clamp the device securely onto the colon wall, while spots for the ventral scales to gain a purchase and pull the the extensor brings about a positive displacement. The main snake along. Most species use a type of movement called serdifficulty of this technique is to be able to acquire sufficient pentine locomotion, in which the body assumes a position of a friction/grip to anchor the clamper onto the slippery colon wall. series of S-shaped horizontal loops, and each loop pushes In 1961, Drapier et al. [2] developed an automatic locomoagainst any surface resistance. tive device for a catheter using the inchworm locomotion techIn 1988, Ikuta et al. [8] developed an active endoscope that nique. He also introduced two methods of acquiring adhesion uses shape memory alloy (SMA) to guide a snakelike robot between the clamper and the colon wall; the suction and around obstacles. The SMA tendons were arranged around a expansion method. In both methods, the extensor is integrated spine so that each section can bend in three dimensions. The with an expansion spring to allow it to return to its original snake was operated manually via a joy stick controlling the length once the pressurized air to extend it is removed. two tip segments, and the tip bending instructions are then In 1979, Frazer [3] adopted a similar technique with the passed back along the line as the endoscope is then pushed expansion method of clamping and patented a design conforward so that subsequent sections follow their preceding segsisting of two radially expandable bladders, separated by an ment. The design comprises five segments, four of which are axially expandable bellows, with only the rear bladder flexible in the same direction on a plane and one segment, attached to the endoscope. Compressed air and vacuum was which is the tip, can bend orthogonally to this plane. The driproposed to respectively expand and contract both bladder ving mechanism of each segment consists of a stainless steel and bellows. Fukuda et al. [4] developed an in-pipe inspeccoil spring, which acts as the main skeleton at the center of a tion robot in 1989, which is capable of moving inside straight or bent pipelines of nuclear power stations. They believe that Elongation Clamping with proper miniaturizaMechanism Mechanism tion and human safety factor consideration, a similar robot design could be developed for automated colonoscopy. Dario et al. [5], [6] used suction to ascertain adhesion onto the colon (a) (b) (c) walls and developed a few prototypes to test its Fig. 2. Dario et al. [5]–[7], microrobotic endoscope: (a) a schematic diagram illustrating the workability. In vitro and mechanical clamping mechanism to grasp onto the tissue; (b) and (c) show the prototype with in vivo tests on animals both suction and mechanical clampers. IEEE ENGINEERING IN MEDICINE AND BIOLOGY MAGAZINE
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joint, and a series of SMA coil springs arranged around it. In this model, one segment has one degree of freedom, so a pair of SMA actuators that are capable of antagonistic motion are arranged in symmetry with respect to the axis. It is this antagonistic activation of the SMA springs that brings about the required bending motion. Millipede Locomotion
Millipedes have many legs that move in waves, and the same principle can be applied to a colonoscope by incorporating legs so that it can be made to move back and forth, thus advancing the endoscope. Utsugi [9] proposed a walking system with three inflatable cuffs that form one section of the millipede, as shown in Figure 3(a). The middle, propellant cuff is the leg, which is pushed backward and forward by the cuffs on either side of it. The sequence of operation is that the propellant cuffs are inflated so that they press against the walls of the colon with enough force to prevent slipping. Next, the drive cuffs are inflated, thereby pushing the propellant cuffs backward so that the sheath, and hence the endoscope, moves forward. The return cuffs are now inflated so that they first lift the wall of the gut off the propellant cuffs and then push those cuffs back onto the deflated drive cuffs. The cycle is now complete, and one forward propelling step has been taken. In 1994, Allred [10] proposed an ingenious design that used washers as feet. In his design, as illustrated in Figure 3(b), the endoscope is surrounded by groups of five washers. All the
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(a) Fig. 3. (a) Utsugi [9] patent and (b) Allred [10] patent.
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Fig. 4. Treat et al. [11], four legged endoscope.
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groups are connected together and move in unison, but within each group, every individual washer can be moved independently. Each of the five washers performs a cycle in which it moves slowly backward and then rapidly forward. If all five washers did this together, then the endoscope would simply rock back and forth. By forcing all of them to be out of phase such that, at any one time, four are moving slowly backward and only one is moving rapidly forward, the frictional force resisting skidding is independent of the speed of the skid. In this case, the forward propulsion from the four slow washers outweighs the reverse thrust from the one fast washer, and the endoscope slowly advances. Lizards and Ants Locomotion
Perhaps the most intriguing behavior about lizards is its ability to run right up vertical walls and across ceilings in an upside down manner. Their special toe scales, which stick to surfaces very effectively, gives them that advantage. Interestingly, ants display a similar behavior of climbing walls with ease. In 1997, Treat et al. [11] present a four-legged device with legs that can literally walk along the colon. The animal analogy is striking, and the creature has a single eye which sends a video image out through its tail to the endoscopist [Figure 4]. The legs of the robotic endoscope comprise four pneumatic linear actuators. When activated, self-propelled motive force is produced by pushing against the inner surfaces of the colonic wall. By activating the actuators in sequence, the robot can traverse by itself. Backward motion 112 can be achieved by pivWasher 112 oting the actuators to point in the opposite direction. However, due to the rigidity of the robot, it may not be flexible enough to negotiate the bends found in the colon. 114 Adopting a similar 110 concept, Phee et al. (b) [12], [13] embraced the idea further to develop the EndoCrawler. It is made up of five rigid segments joined together by a passive flexible rubber bellows. Four rubber bellows actuators are connected (90◦ apart) to each segment. A hollow central cavity, which runs through the whole length of the robot, houses the air/water tubing, optical fibers, CCD cables, and the biopsy channel. A steerable distal end was integrated to allow flipping of the scope during colon inspection. When air is introduced into the bellows actuators, it extends longitudinally until it touches the colonic wall at 45°, thus creating a resultant force that pushes the robot forward. When vacuum is introduced, the bellows will collapse. By activating the actuators at specific intervals, a variety of gait sequences are achieved. Different gait sequences can be achieved from the EndoCrawler; however, different gait sequences will perform better under different conditions. For example, for a gait sequence activated antagonistically, it performs well in a horizontal environment but fails if the path is vertical, against gravity. Therefore, a robust gait sequence should be ascertained in order to locomote inside the colon. MAY/JUNE 2006
Octopus Locomotion
An octopus escapes from its predators by squeezing water from its mantle and jetting away. The physical principle is that a mass is accelerated through an orifice and the resultant force produces a reaction that pushes the octopus in the opposite direction. It is the same principle that drives a rocket or a jet engine. Ginsburgh et al. [14] proposed that this principle could be used to propel a borescope. As shown in Figure 5(a), the tip of a borescope was attached with a tube (42 on the figure) that supplies pressurized liquid to the rear facing nozzle (40). As fluid is passed through the pipe, thrust in the opposite direction is generated as the fluid accelerates through the nozzle. As a result, the borescope advances. In 1998, Mosse et al. [15], [16] further developed the water jet propulsion method by constructing prototypes and testing them in models. Water is pumped to a headpiece at the tip of the scope where it is sprayed out of backward facing nozzles [Figure 5(b)]. As the water accelerates through the nozzles, the inertia force propels the endoscope tip forward. An in vivo experiment was conducted with a live pig using a water flow rate of 5 L/min and a pump pressure of about 20 Bar. The prototype was able to travel up to about 300 mm proximal to the anus. The wastewater flowed harmlessly out of the anus and could be easily collected. Despite pulling and pushing the endoscope along the bowel about a dozen times, the bowel was not damaged, although considerable redness and soreness could be seen. Locomotion Using Telescopic Technique
et al. [18]. For a forward motion, the head solenoid is activated, thus causing the permanent magnet to move toward it. Upon impact, a force is generated, which moves the actuator forward. After impact, the current direction of the head solenoid changes, therefore a repulsive force is induced onto the permanent magnet, causing it to move backward. The actuator moves forward continuously by repeating the sequence. Two prototypes of different sizes were built to verify the locomotion idea, and both prototypes move in accordance to the design. The larger size prototype advances faster than the smaller prototype due to its higher inertia. However, the design does encounter setback similar to that of the water jet principle; inadequate force produced to power the robotic colonoscope. The heat generated to magnetize the body should also be contained within a safe margin guideline of the health organization. Locomotion Using Natural Peristalsis
Modern endoscopes allow routine inspection of the upper and lower regions of the abdomen, yet the small bowel can still only be inspected with great difficulty. If a camera, light source, transmitter, and power supply could be made small enough to fit into a capsule that could be swallowed, then pain-free endoscopy would be possible. In 1997, Iddan et al. [19] patented an idea describing a swallowable capsule integrated with a minute camera system, light, and power supply. The camera is housed inside a capsule whose front portion is a transparent cone, and the image transmitted is of the mucosa sliding over this transparent cone as peristalsis pushes the capsule through the intestines. In 2000, Gong et al. [20] developed a dual capsule wireless endoscope prototype, which houses a miniature CCD camera, a processor, and a halogen light in one capsule and a microwave transmitter and batteries in another. The prototype was surgically inserted into the stomach of anaesthetized pigs. Using receiving aerial augmentation, good quality color images were received, showing detail of the stomach wall and contractions of the pylorus. The prototype
In 1976, Masuda [17] filed a patent proposing that a flexible fiberscope (item 36 in Figure 6) could be fed through a conduit by attaching it to the end of an everted tube, i.e., a tube whose end has been turned inwards and pulled back through itself. It can be seen that when the tube is filled with pressured liquid, it will unroll itself and pull the endoscope forward. Since the tube is rolling against the conduit wall, there is no sliding between it and the wall. From the dia42 gram, in the design there seems to be no annular 40 3 space to pass instruments 41 unless Item 35 is made A big enough. The process of unrolling looks simC 3 ple, but it must be remembered that in 3-D, B D the diameter is expanding as it rolls outward. If (a) (b) the everting tube is not to balloon out and stretch Fig. 5. (a) Ginsburgh et al. [14] patent, borescope propelled by a jet at its tip and (b) Mosse et al. the colon, then it must [15], [16] invention, a water jet propelled colonoscopy. not go on stretching once it has everted, which might be possible using a braided materi1 al. Such a material would have to be crumpled up before 34 33 3 everting, and unless it was extremely flexible, there might be 35 10 problems in unraveling it once the tube had been bent around the sigmoid colon and the splenic flexure. 17
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Locomotion Using Impact
A robotic endoscope that locomotes by colliding a movable permanent magnet against two electrically magnetized stationary magnets on each side of a cylinder was proposed by Hyun IEEE ENGINEERING IN MEDICINE AND BIOLOGY MAGAZINE
Fig. 6. Masuda [17] patent, an everted tube is used to pull a fibrescope through a conduit.
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was removed surgically after the experiment. This study demonstrates the feasibility of transmitting high-quality images through the abdominal wall with a small microwave and radio frequency transmitter. It was also the first to report successful wireless transmission of a moving color television image of the stomach in a living subject. An Israeli company, Given Imaging [21], developed the first commercial disposable capsulated pill named M2A. The single capsule design incorporates a light source, a miniature complementary metal oxide semiconductor (CMOS) color camera, a battery, an antenna, and a radio transmitter. Images captured by the video camera are transmitted by radio frequency to an array of sensors worn around the patient’s waist, where the signals are recorded digitally. No hospitalization is required when using M2A. The patient simply swallows the pill, puts the sensor around the waist (like a portable walkman), and proceeds with his daily affairs. After approximately eight hours, or after detecting that the capsule has been excreted, the patient removes the sensor and returns it to the clinic where the images are downloaded and the doctor examines the video to look for abnormalities. The entire process is painless and convenient for both patient and doctor. Still at its primarily stage, the Intelligent Microsystem Center [22] in Korea is developing a microcapsule named MiRO #1, as illustrated in Figure 7, which has the ability to
advance forward, backward, orientate, stop, and anchor itself onto the colon wall at will. Only 10 mm in diameter and 20 mm in length, it is equipped with a micromanipulator arm that is able to perform therapeutic procedures like taking tissue samples and administering an injection. The images are transmitted wirelessly, and it is also integrated with a position tracking device. Discussion
The primary objective of a robotic colonoscope is to propel itself from the rectum right up to the caecum without damaging the delicate colon walls, while carrying a camera, light source, biopsy channel, and air/water tubing. From reviewing other researchers’ work, clinical observations, and practical experience, the following characteristics are proposed to successfully develop a working robotic colonoscope. ➤ The body of the robot must be flexible enough to conform to the acute bends found in the colon. Any rigid distances must be kept to a minimum (max: 40 mm). ➤ The rigid diameter of the robot should not be greater than 29 mm, which is the smallest average internal diameter of the colon (rectal sigmoid). ➤ The robot’s body surface must be made of biocompatible material to eliminate any reaction between the robot and the colon tissue. ➤ A very experienced colonoscopist would take less than 5 min to reach the caecum, whereas a new hand would take 20–30 min. The robotic colonoscopy should be Micro Syringe Micro Optics placed in the “experienced” category, Temperature Sensor therefore, the authors feel that a benchpH Sensor mark of about 6–8 min for an automatic Chemical Sensor self-propelling robot to reach the caecum Stopping Mechanism would be optimal. ➤ The locomotion technique should not disMicro Tool Micro Pump turb the colon tissue and should keep to its RF Com. bare minimum to preserve the original integrity of the colon walls, which Mini Battery accounts for an accurate diagnosis and Signal Processor indirectly reduces discomfort experienced by the patient. Extension DC/DC Mechanism Figure 8 shows an overall picture of the litConverter erature reviewed in this article. It can be seen that most locomotion techniques depend on the colonic walls as a platform for the robot’s Fig. 7. Intelligent Microsystem Center [22], MiRO 1 Endoscopic Microcapsule. advancement. For instance, the animal
Locomotion Technique Mechnical and Other Method
Animal Locomotion Earthworm
Snake
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Utsugi Drapier et al. Ikuta et al. Sturges et al. Allred Frazer Fukuda et al. Burdick et al. Vijayan et al. Dario et al.
Treat et al. Phee et al.
Octopus
Wheel and Pully Telescopic Impact
Ginsburgh et al. Mosse et al.
Takada Goh et al.
Natural Peristalsis
Masuda Hyun et al.
Iddan et al. Gong et al. Given Imaging Intelligent Microsystem Center
Fig. 8. An overall picture of the literature reviewed in this article.
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locomotion method (earthworms, lizards, and ants) uses the basic principle of establishing a base to anchor part of its robot body onto the colon walls in order to push itself forward. The bases were achieved by either stretching the colon walls until they can no longer stretch further, sucking the colon walls (causing them to wrap the robotic element), physically clamping the colon wall with movable jaws, or digging into the colonic walls. At some portion of the colon, where the surrounding organs are relatively hard, e.g., the kidney, the amount of stretching reduces since these organ resist the colon movement, thus creating a resultant force to transverse the robot. The propulsion method mimicking a millipede, snake, and using mechanical means (wheels and pulleys) adopt the traction principle to advance the robot by ascertaining friction between the robotic element and the colon walls. However, due to the nature of the colon, which is highly elastic and slippery due to the presence of mucus, establishing an anchor area or traction is very difficult. Once the anchor area or traction is ineffective, mainly due to slippage or insufficient friction, no advancement will occur. This is normally what happened where the robot executed its manipulation sequence without achieving any locomotion. Perhaps the most promising work developed from these locomotion techniques is the inchworm method that uses suction and a mechanical clamp, integrated with a monkey style of swinging. Since it ensures a mechanical grip onto the colon walls and a positive advancement of the robot, slippage is very much reduced. Another approach to locomotion is where the locomotion technique is independent of the colon wall; for example, the octopus, telescopic, impact, and natural peristalsis principles. The octopus propulsion principle is a practical method of delivering propulsion, however, the question of force becomes an issue. If the required propulsion force is low, say 1 N, then this method is useful. However in the case of a colonoscopy, the force required is much larger. Increasing the force requires increasing the mass flow rate or the velocity of the water, which would compromise the safety and risk of the patient and are much harder to assess. In view of these difficulties, the jet propulsion idea has to be carefully reviewed. The telescopic method using the everting tube is a very simple design; it does not slide against the colon wall and keeps on increasing in length by introducing pressure inside the annular space. However, the inherent need for the tube to straighten when elongating indirectly implies straightening of the colon, which is not permitted in the human body. The impact principle has a similar downfall as the octopus principle, the driving force is inadequate to pull it through the colon. Locomotion through natural peristalsis using a wireless, swallowable capsulated endosopy is designed mainly for screening of the small intestine. In the large bowel, which is normally in its collapsed stage, the tissue would likely to wrap around the capsule, thus hindering the visualization, and would probably miss small polyps. If the capsule is designed to inflate, then the capsule can increase its size when entering the large intestine to detect abnormalities in the colon. With the implementation of a micromanipulator arm and the ability to control the capsule’s movement and orientation at will, this would be a huge advantage when evaluating the small intestine. Both diagnosis and therapeutic procedure can be performed simultaneously. The ability to move against the natural peristalsis of the gastrointestinal (GI) track would be ideal for colonoscopy as a larger version of the capsule, appropriate for IEEE ENGINEERING IN MEDICINE AND BIOLOGY MAGAZINE
colon, can be developed that can be inserted through the anus and moved to the caecum under the guidance of the doctor. The primary goal of researchers is to develop a locomotive technique that can efficiently travel in the colon. Once a locomotion method proves to be working, the safety issue will be addressed, and it varies from one design to another. Consideration such as air pressure, stretching of the colon walls, clamping or sucking force, and undesired marks on the colon walls are some of the parameters that must be evaluated. Conclusions
This review article discusses the work done by researchers in the quest to automate the colonoscopy procedure. The results of some of the researchers seem very promising. In vitro and in vivo experimentation have been carried out to prove the possibilities of a robot crawling along a patient’s colon, treating polyps as they are encountered. The authors believe that in the future, say 10–15 years, conventional colonoscopy will be revolutionized, giving way to robotics to assist doctors in conoloscope manipulation and performing therapeutic procedures and leaving doctors to concentrate on the diagnostic aspect of the procedure, which would encourage mass screening as more patients can be evaluated per session. Irwan Kassim received his B.Eng. degree from Queensland University of Technology, Australia, in 1997 and his M.Eng. from Nanyang Technological University (NTU), Singapore, in 2003, both in mechanical engineering. Currently, he is a research fellow at National Neuroscience Institute (NNI), Singapore, in association with the newly setup Advance Integrated Medical Systems (AIMS) Laboratory embarking on a robot for skull base surgery project. His work on robotic colonscopy project was during his term as a research associate and master candidature in Computer Integrated Medical Intervention Laboratory (CIMIL), NTU. He received a Silver Medal in Tan Kah Kee Young Investors’ Award in 2001 for his entry “Robotic Colonoscopy.” His research interests include medical robotics, mechatronics, and biomedical engineering. Louis Phee received his B.Eng. and M.Eng. from Nanyang Technological University, Singapore, in 1996 and 1999, respectively. He later obtained his Ph.D. from Scuola Superiore Sant’Anna, Pisa Italy in 2002. He is currently an assistant professor at the Nanyang Technological University, Singapore. His research interests include medical robotics and mechatronics in medicine. He is also the principal investigator of a few government-funded research projects. Wan S. Ng is an associate professor at the School of Mechanical and Production Engineering, Nanyang Technological University, and a fellow of IMechE (U.K.). He is also the head and founder of the Computer Medical Intervention Laboratory (CIMIL). Under his leadership, CIMIL obtained a number of research MAY/JUNE 2006
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grants from the Singapore government to conduct research ranging from image processing and computer visualization to robotics. The projects seek to help surgeons in both learning and execution, which can lead to improved clinical outcomes. More can be found at http://mrcas.mpe.ntu.edu.sg. CIMIL actively collaborates with several consultants in the local hospitals as well as overseas research institutions such as Imperial College of London, the United Kingdom and Rochester University of New York. His research interest is in medical robotics, computer assistance in surgery, and the safety of medical robots. Feng Gong received his B.Sc. in precision engineering from Harbin Institute of Technology, China, in 1983; his M.Sc in engineering from the University of Warwick, the United Kigndom, in 1994; and a Ph.D. in medical physics and bioenginnering from the University of London (UCL), the United Kingdom, in 1999. He spent nearly nine years in the Department of Medical Physics and Bioengineering, UCL, where he worked on several projects that aimed to design, develop, and test miniature instruments for flexible endoscopy and to develop novel techniques for wireless endoscopy. In May 2000, he joined the School of Mechanical and Production Engineering, Nanyang Technological University, Singapore, as an assistant professor. His major research areas include endoscopic suturing techniques, endoscopic miniature instrument development, and wireless video capsule technology. Paolo Dario received his Dr. Eng. Degree in Mechanical Engineering from the University of Pisa, Italy, in 1977. He is currently a Professor of Biomedical Robotics at the Scuola Superiore Sant’Anna in Pisa. He also teaches courses at the School of Engineering of the University of Pisa and at the Campus Biomedico University in Rome. He has been a visiting professor at Brown University, Providence, Rhode Island, at the Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland, and at Waseda University, Tokyo, Japan. He was the founder of the ARTS (Advanced Robotics Technologies and Systems) Laboratory and is currently the coordinator of the CRIM (Center for the Research in Microengineering) Laboratory of the Scuola Superiore Sant’Anna, where he supervises a team of about 70 researchers and Ph.D. students. He is also the director of the Polo Sant’Anna Valdera and a vice director of the Scuola Superiore Sant’Anna. His main research interests are in the fields of medical robotics, mechatronics and micro/nanoengineering, and specifically in sensors and actuators for the above applications. He is the coordinator of many national and European projects, the editor of two books on the subject of robotics, and the author of more than 200 scientific papers (75 on ISI journals). He is an editor-in-chief, associate editor, and editorial board member of many international journals. Charles A. Mosse studied politics, philosophy, and economics at Oxford University and applied mechanics at Cranfield Institute of Technology before taking up an appointment of 56 IEEE ENGINEERING IN MEDICINE AND BIOLOGY MAGAZINE
Medical Physicist at University College, London, the United Kingdom. From 1980–1988, he worked on blood-gas and pH monitoring using electrochemical and optical sensors. He next worked on an optical system for measuring facial morphology and a technique using serial computed tomography (CT) scans to make titanium plates for cranioplasty. In 1992, he left to work for a dairy packaging company but returned in 1996 to undertake a Ph.D. titled “Devices to assist the insertion of colonoscopes,” which was completed in 1999. Since then he has divided his time between working on endoscopic devices and on light-delivery systems for photodynamic therapy (PDT) and for interstitial laser photocoagulation (ILP). Address for Correspondence: Wan S. Ng, School of Mechanical Engineering and Production Engineering, Computer Integrated Medical Intervention Laboratory, 50 Nanyang Avenue 639798 Singapore. Phone +65 6790 4411. Fax: +65 6790 1859. E-mail:
[email protected].
References [1] J.M. Church, Endoscopy of the Colon, Rectum and Anus: New York: IgakuShoin Medical Publishers, 1995. [2] M. Drapier, V. Steenbrugghe, and B. Successeurs, “Perfectionnements aux cathéters médicaux,” France Patent 1,278,965, 1961. [3] R.E. Frazer, “Apparatus for endoscopic examination,” U.S. Patent 4,176,662, 1979. [4] T. Fukuda, H. Hosokai, and M. Uemura, “Rubber gas actuator driven by hydrogen storage alloy for in-pipe inspection mobile robot with flexible structure,” Proc. IEEE Int. Conf. Robotics Automation, Scottsdale, AZ, 1989, pp. 1847–1852. [5] P. Dario, M.C. Carroza, B. Lencioni, B. Magnani, D. Reynaerts, M.G. Trivella, and A. Pietrabissa, “A microrobot for colonoscopy,” in Proc. 7th Int. Symp. Micro Machine Human Science, IEEE, Nagoya, Japan, 1996, pp. 223–228. [6] L. Phee, D. Accoto, A. Menciassi, C. Stefanini, M.C. Carrozza, and P. Dario, “Analysis and development of locomotion devices for the gastrointestinal tract,” IEEE Trans. Biomed. Eng., vol. 49, no. 6, pp. 613–616, 2002. [7] A. Menciassi, A. Arena, L. Phee, D. Accoto, C. Stefanini, G. Pernorio, S. Gorini, M. Boccadoro, M.C. Carrozza, and P. Dario, “Locomotion issues and mechanisms for microrobots in the gastrointestinal tract,” in Proc. 32nd Int. Symp. Robotics, Seoul, Korea, 2001, pp. 428–432. [8] K. Ikuta, T. Masahiro, and S. Hirose, “Shape memory alloy servo actuator system with electric resistance feedback and application for active endoscope,” IEEE Int. Conf. Robotics Automation, Philadelphia, PA, 1988, pp. 427–430. [9] M. Utsugi, “Tubular medical instrument having a flexible sheath driven by a plurality of cuffs,” U.S. Patent 4,148,307, 1979. [10] J.B. Allred, “Self advancing endoscope,” U.S. Patent 5,345,925, 1994. [11] M.R. Treat and W.S. Trimmer, “Self propelled endoscope using pressure driven linear actuators,” U.S. Patent 5,595,565, 1997. [12] S.J. Phee, W.S. Ng, I.M. Chen, F. Seow-Choen, and B.L. Davis, “Locomotion and steering aspects in automation of colonoscopy,” IEEE Eng. Med. Biol. Mag., vol. 16, no. 6, pp. 85–96, Nov. 1997. [13] S.J. Phee, W.S. Ng, I.M. Chen, F. Seow-Choen, and B.L. Davies, “Visual control aspects in automation of colonoscopy,” IEEE Eng. Med. Biol. Mag., vol. 17, no. 3, pp. 81–88, Mar. 1998. [14] I. Ginsburgh, J.A. Carlson, G.L. Taylor, and H. Saghatchi, “Method and apparatus for fluid propelled borescopes,” U.S. Patent 4,735,501, 1988. [15] C.A. Mosse, T.N. Mills, and C.P. Swain, “A water jet propelled colonoscope,” 6th United European Gastroenterology Week (UEGW), vol. 41, Suppl. 3, p. E2, 1997. [16] C.A. Mosse, C.P. Swain, G.D. Bell, and T.N. Mills, “Water jet propelled colonoscopy—A new method of endoscope propulsion,” Gastrointest. Endosc., vol. 47, p. AB40, 1998. [17] S. Masuda, “Apparatus for feeding a flexible tube through a conduit,” UK Patent 1,534,441, 1978. [18] J.M. Hyun, J.L. Hvung, M.L. Young, J.P. Juang, K. Byungkyu, and H.K. Soo, “Magnetic impact actuator for robotic endoscope,” in Proc. 32nd Int. Symp. Robotics, Seoul, Korea, 2001, pp. 1834–1838. [19] G.J. Iddan and D. Sturlesi, “In-vivo video camera,” U.S. Patent 5,604,531, 1997. [20] F. Gong, C.P. Swain, and T.N. Mills, “Wireless endoscopy,” Gastrointestinal Endoscopy, vol. 51, no. 6, 2000. [21] Given Imaging, “Expanding the scope of GI—M2A,” [Online]. Available: http://www.givenimaging.com [22] Intelligent Microsystem Center, “Endoscopic microcapsule,” [Online]. Available: http://www.microsystem.re.kr
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