| Traditional gastrointestinal (GI) tract examinations use push-and-pull endoscopes, examination processes using it are usually painful, incapable of reach small intestine, and with relatively high probability of cross infection. Passive capsule endoscope technology has been greatly improved in last ten years. It overcomes many defections of traditional push-and-pull endoscopes, and become a mature technology. However, passive capsule endoscopes are born with some defections, such as: 1) time consuming (typically 6-12 hours) and impossible to conduct online diagnosis; 2) unable to locate the capsule endoscope to suspected infection; and 3) sometimes capsule retention happens and needs invasive surgery. In order to conquer those problems and offer capsule endoscope more medical potential, institutions across the world are actively studying many methods of capsule endoscope active locomotion, including SMA method, spiral structure method, electro-stimulation method, motor method and hydraulic method. These methods aim at integrate propeller and actuator into endoscopic capsule, which will not only raise the complexity and cost of the disposable capsule, but also reduce its reliability. On the other hand, using outer magnetic field to realize active locomotion is a more promising way. University of Virginia investigated a magnetic navigation system used in neurosurgery in 1980, which uses outer magnetic field navigates small magnetic balls to brain tumor to conduct heat treatment. Later, it developed into an invasive cardiovascular treatment system– Stereoaxis, and achieved commercial success.Based on these considerations, we combine the outer magnetic field navigation method with active locomotion capsule endoscope, and propose a magnetic propelling active locomotion capsule endoscope system. The propelling method is carefully investigated. A model depicts the capsule contact with intestine is built to estimate its function requirements and optimize structure of endoscopic capsule. A model of outer magnetic field is also built to investigate the feasibility and optimized key parameters of the proposed system. A prototype magnetic propelling active locomotion capsule endoscopic system is designed, manufactured, and analyzed. The prototype system uses two symmetrical mounted permanent magnets to generate an outer magnetic field, and applies a 5– DOF mechanical structure to manipulate and regulate the distribution of the outer magnetic field in order to control the motion of endoscopic capsule in GI tract, which not only save costs but also avoid the negative effects on health resulted by alternating magnetic feild. The endoscopic capsule is built with commercialized universal chips instead of ASIC, and has advantages of low cost, multi-function and compatible with magnetic propelling system. Calibration experiments, simulated intestinal tests and vision guidance experiments are performed; the material and methods used in those experiments are recorded. Test result shows that the proposed system is save for patients, and helpful for faster and better diagnosis. The average moving speed of the capsule is 5mm/s in simulated intestine experiment, which means the system is capable of finish a small intestine inspection in 30 minutes, greatly improve examine efficiency, and enables online diagnosis. The system is also capable of examine both small and large intestine, expand inspection area, and eliminate the potential safe risk of capsule retention. In addition, the system enables both fast diagnosis and located careful observation, which is particularly beneficial for online pin point diagnosis. |
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