Final Design

(Refer to Final Mold Design  for more information on our mold)

The final flap design is designed to be folded backwards, which eliminates the need for an insertion tip. Moreover, this design solves the potential issue of the flap being lodged inside the anal canal and not being able to extend itself while folded backwards. Finally, the v grooves near the interface between the flaps and the device reduces stiffness which made folding forward easier.

The Bottom Flange has to prevent the air retention device from slipping into patient’s body while the doctor sliding the scope through it. Bottom Flange should also be able to prevent leakage of air or water from patient anal canal by sealing the outside of the person’s anal sphincter.Although it is easier to manufacture a basic round flange, the contour-forming flange is superior in other respects. The contour on the flange is ergonomically designed to  create an improved seal by letting the buttocks clamp on the contour. Moreover, it has been proven that the contour-forming flange is only slightly harder to mold while improving the seal thus the contour-forming flange is used on final design.

The Clip has to allow the device to slip over a colonoscope that has already been inserted. The reason is that it is more convenient for the doctor to slip the device over the colonoscope and not have to take the scope out, reapply the device, and then insert it into the patient again. The clamp also can’t compromise the seal or introduce a significant amount of friction. Since the sponsor wanted the ability to use the device after the colonoscope has been inserted into the patient, there needs to be an opening for the scope to slip through. Since the air retention device has a slit in the middle, there needs to be a system of  retention that holds it together. Several ideas floated around included a PDMS casted strap with keyways, and a rigid clip.

The Inner seal needs to prevent leakage of air or water, and at the same time not exert an excessive amount of friction on the scope.. The dimension of the round seal, and the location was determined after listening to feedback from Dr. Kalmaz, the project sponsor. As the seal diameter gets smaller, there would be more surface area in contact with the scope and there would be more friction. Both Seal design options have pros and cons and they are fair tradeoffs. Normal seal is much easier to produce than Ian seal but its sealing ability is doubtful while Ian seal is expected strong sealing but more friction upon withdrawal as the tip of Ian seal rolled down with the scope. After the team tested out both seal prototypes, it is found that leakage of normal seal is not manageable. According to test results in Chapter 5, team decided to choose Ian seal for the inner seal design.