Miniaturisation, Modularization and Evaluation of the SoftSCREEN System

Early detection of precancerous forms in the intestine, e.g. adenomatous polyps, can be achieved with regular screening programmes of the lower gastro-intestinal tract (GI) by means of flexible sigmoidoscopy and colonoscopy. Screening of the GI tract is of paramount importance to reduce the high death rate of patients affected by colon cancer worldwide. Nonetheless, colonoscopy typi- cally causes discomfort and often requires sedation for the patient because of its invasiveness and abdominal pain as- sociated with it. Research on robotic-assisted colonoscopy is advancing in the design of minimally invasive devices aimed at the inspection of the GI, with the goal of reducing the discomfort caused to the patient while resulting in a safer and more successful procedure [1]. Multiple loco- motion strategies have been explored to enable front-head locomotion of endoscopes, to minimise the interaction forces between the scope and the intestine wall, as these forces are typically the first cause of discomfort for the patient. Extensive studies have been conducted in the context of track-based miniaturised robots such as [2] and [3]. However, due to the fixed geometry of these systems, adapting to the variable and irregular lumen of the colon to enable full body track-based navigation is not possible. Furthermore, as per many of the robotic solution presented to date for GI screening, there is also a need to drag a tether, the frictional resistance of which grows the more the robot advances in the intestine. Soft materials properties have inspired research of mechanism to accomplish a compliant interaction with the tissue, such as the use of inflatable balloons for double balloon endoscopy. In our previous work [4], we have presented a novel robotic system for colonoscopy called SoftSCREEN. The proposed system relies on track-based locomotion and shape reconfiguration enabled by two inflatable chambers capable of displacing the elastic tracks to conform to the local geometry of the lumen, enabling full-body track navigation. In this seminal paper we have validated the proposed desing in a 2:1 scale system and demonstrated that not only is possible to reconfigure our system to always match the lumen navigated, but also to control the force applied on the walls by means of pressure regulation, and, as a result, fine tuning the traction force of our system. In this work, we present the first miniaturised and modularised prototype of the SoftSCREEN system, designed to create a sterilisable reusable expensive compo- nent and a cheap disposable component. We then evaluate this first prototype in a 1:1 scale phantom.