The role of geometry in the friction generated on the colonic surface by mucoadhesive films

One of the main challenges in designing diagnostic devices able to move along the colon is their locomotion method. Generating friction without applying high normal forces is a key requirement in order to eliminate the risk of tissue damage. One possible solution is to generate friction by means of adhesive forces. For this reason, the device can be covered with mucoadhesive films, which are able to stick on the colonic surface. This paper identifies that the friction of mucoadhesive films depends strongly on their geometry. It seems therefore feasible to adapt the level of the friction to the properties of the colonic surface by altering the geometry of the films covering the device. Moreover, an eventual influence of the film geometry on the generated friction can reveal film shapes which create high grip despite their small size, leading to a decrease in the overall size of the device. The aim of the paper is to test in vitro the relationship between film geometry and generated friction, to fit the experimental findings in a simplified but generic macroscopic theoretical model able to predict the behavior of various geometries, and to embed those findings in the principles of the design implementation. (c) 2006 American Institute of Physics.