Tubular locomotion and positioning using tip eversion for endoscopy

Colonoscopy is a minimally invasive procedure to examine the large intestine using a flexible endoscope. Currently, colonoscopic procedures require physically pushing the endoscope through the large intestine which potentially imparts damaging forces on the intestinal wall, requires a high level of expertise to perform safely, and can require extensive procedure time. This paper presents the use of inverted tubular element locomotion (ITEL) for improved endoscope translation and positioning that works via tip eversion of inverted plastic tubes. Experiments were performed to examine the fluid pressure required for locomotion through a large intestinal model and in both straight and curved paths and determine the optimal tube dimensions for insertion via ITEL. Experiments were then performed to compare intestinal forces during manual and ITEL-based insertion. The experiments established a relationship between the tip eversion pressure and the tube thickness and diameter. In addition, it was found that pressure required for locomotion was only minimally impeded by being enclosed in the intestinal manikin but significantly impacted by the curvature of the turn. Measured insertion forces for ITEL were found to be 10.1% less compared to traditional insertion. These results will aid in the future design and development of ITEL for endoscopic positioning.