Self-Propelled Colonoscopy Robot Using Flexible Paddles

The number of patients suffering from colorectal cancer (CRC) has been increasing. CRC is known to be curable if detected and treated early. Colonoscopy is currently one of the best screening methods for CRC because it can observe and treat disorders in the large intestine. However, operating the colonoscope is technically demanding for doctors because the insertion of the instrument into the large intestine requires considerable training and skill. To address this issue, we propose a novel self-propelled robot with flexible paddles for the intestinal tract. In this device, the torque is transmitted from a motor outside the patient body to a worm gear at the tip of the colonoscope by a flexible shaft. The worm gear is engaged with two spur gears, and flexible paddles fixed to these spur gears contact the wall of the large intestine to provide the propulsive force. We constructed a force transmission model of the robot to confirm the suitability of the design. The prototype of the self-propelled robot was fabricated by a 3D printer, and its locomotion in a simulated rubber intestine was evaluated. The velocity of the robot was faster than the required speed of 6.5 mm/s. The propulsive force was approximately 1 N; thus, the effectiveness of the robotic principle was confirmed. The mechanical locomotion design, its fabrication, and analysis results are reported in this letter.