Development of PlastoLock overtube with temperature controlled rigidity for colonoscopy

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To diagnose and treat colon cancer a colonoscopy is usually performed. Current colonoscopy is performed by advancing a colonoscope (scope) through the tortuous colon. However, the flexible scope often buckles when advanced. This can cause discomfort and pain for the patient and can make the examination of the colon difficult for the endoscopist. Guiding the scope, with an overtube that has a controllable rigidity, when the scope is advanced could reduce these problems. The rigidity of the overtube should be switched between a flexible state, that allows the insertion of the overtube, and a rigidified state that provides sufficient support to the scope. The PlastoLock overtube utilizes the glass transition of Purasorb© PLC 7015 (PLC). By changing the temperature of its PLC components from 43 to 5°C, the PlastoLock overtube is reversibly rigidified. A physical test model of the PlastoLock overtube shaft was developed and its stiffness at 43 and 5°C was determined. The tests showed a reliable, reversible and fast change in stiffness. The stiffness of the test model in flexible state is sufficiently low. However, the stiffness of the rigidified test model is insufficient. A larger change in stiffness was found when testing the test model submerged in water compared to passing water through the PLC components. The measured stiffnesses were considerably below expectation. Possible causes for this discrepancy were investigated, but require further testing to confirm. These future tests should also indicate whether the stiffness of the rigidified test model can be increased.