| The state-of-the-art in enteroscopic surgery and therapeutic care continues to minimize invasiveness, cost, surgery time, and patient trauma. To this end, a new class of medical device, called the robotic capsule endoscope, is being pursued by multiple research groups. These potentially swallowable devices will radically expand the capabilities of natural orifice surgery by performing non-invasive tasks within the gastrointestinal tract that are now only possible with enteroscopic, laparoscopic, or open surgery. It is necessary for a robotic capsule endoscope to possess active, controlled mobility, which involves interactions between gastrointestinal tissue and engineering materials. Design challenges stem from the nonlinear and variable mechanical and physiological response of tissue and organs to the robot and from poor understanding of interfacial properties. In this work we initiate a study of the mechanical properties of the small intestine with the goal of accelerating the development of in vivo robotic capsule endoscopes for the gastrointestinal tract. To this end, four investigative devices and testing methods are presented: (1) A novel tribometer that measures the in vivo coefficient of friction between the mucosa and the robot surface; (2) An in vitro biaxial test apparatus and method for characterizing in-plane biomechanical properties of the bowel wall; (3) An in vitro test protocol to characterize the adhesive properties of mucosa; and (4) A novel manometer and force sensor array that measure the in vivo myenteric contact force against a solid bolus. Using these devices and test methods, the tribometry, passive biomechanics, mucosal adhesivity, and contractile response of the small intestinal tissue from multiple porcine models are measured. The results of this study offer crucial yet previously unknown biomechanical properties of the small intestine and have provided a foundation for the development of a unified and comprehensive model of the interactions between a robotic capsule endoscope and the intraluminal environment. |
