Influence of Circumferential Extension on Friction of Small Intestine

In previous works, when studying the frictional behaviour of the small intestine, the small intestine was always in a natural state. However, when a capsule endoscope is travelling through the small intestine, since the diameter of the capsule endoscope may larger than the small intestine, the small intestine is then expanded in circumferential direction, which implies that previous works are not sufficient. This work uses flat–flat contact to simulate a capsule travelling through the small intestine, comparing the frictional behaviour of the small intestine in its natural and circumferentially expanding states, analysing the effects of other factors such as load, velocity and lubrication, which provides a realistic basis for the optimisation and control of magnetically controlled endoscopes. Graphical abstract