The Housing of a Modular Robot for Colonoscopy


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Since most of the readers might not be professionals in this area. I would make it as easily understandable as possible. Thus there might be terms that are not technically accurate.
Colonoscopy is a procedure that checks the entire large intestine, which is the last part of human digestive system. During the process, the colonoscopist inserts a scope (basically a rubber tube with camera, water/air supply tubes and biopsy forceps inside, measures about 160 cm in length and 12mm in diameter) into the patient’s rectum (last part of the large intestine) to check the colon for abnormality (such as tumor or polyp) and perform surgery if needed. The scope has a flexible distal tip that can be bent upward and downward (0 to 160 degrees) and left and right (0 to 180 degrees) manipulated by the doctor with a control head at the proximal end. Generally, due to the complexity of the colon and the stiffness of the scope, it is hard to propel the scope forward all the way to the cecum, even for an experienced doctor. The doctor needs to navigate the distal tip according to the images (captured by the camera) and sometimes by their feelings (the force they are experiencing in their hands). Also, the patient can experience discomfort during the process. (http://www.youtube.com/watch?v=ewCIqAAJGPg), video, remove a polyp.
To make this procedure better, I am making a robotic colonoscope distal tip that can adjust its shape automatically according to the shape of the colon. The robotic system is made of three modules with each module equipped with two servo motors, three infrared sensors, a processor, a bluetooth module and a battery. They are connected in series to form a snake-like robot.
Relation with 3D printer:
Each module has a housing that houses those parts mentioned above. Basically it is a cylinder with very thin wall (about 1mm) and small features. Due to these properties, casting is the best option. But it costs too much money and time at prototyping stage. Also, due to the poor mechanical properties (1mm thin plastic ) and small irregular features, it eliminates the way of traditional machining. All these factors make 3d – printing the best choice for now.
Pros and cons:
1. Capable to do complex features.
2. Relatively high accuracy (0.1mm highest).
3. Easily compatible with CAD softwares (CAD, Solide Edge, etc), very few processing techniques involved.
4. Cheap.
1. Poor mechanical properties, discontinuous structures.
2. High frequency of malfunction.
3. Very slow with high accuracy.
4. Hard to remove support materials.
Integrated commons:
3D – printer is an easy handled, highly automated machine. Good for complex and tiny prototyping, for students with less budget, for art models or parts do not require strict mechanical properties, better for solid parts than hollow ones.
For the detail of the printed housing, see the pictures.





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