Despite this, there is nevertheless no possibility of movement. A snail uses the exertions of pressure to change the characteristics of the middle layer, and thus lower the degree of friction, in order to move. In the intestine, however, pressure cannot be exerted, because this would cause the intestine to become deformed. The solution then is found in using smaller and larger surfaces that slide over each other. If a large surface coated with muco-adhesive remains still, and a relatively small surface coated with muco-adhesive begins moving in relation to the larger surface, the smaller surface has less freedom of movement. One by one the small 'hands' of the robot move forward. After this, the entire robot can be slide forward incrementally, whereupon the process of small surfaces shifting begins anew.
Additional experiments found that it is not only the size of the film surfaces, but also their shapes, which influence the degree of friction generated. It's remarkable that the degree of friction increases when the surface size decreases, as a result of holes being made in the structure of the film. It is therefore possible to influence the degree of friction by creating holes in the muco-adhesive or indeed by closing the holes.
Moreover, by selecting different shapes, which owing to their compact size can achieve high degrees of friction, the device can be made smaller. The researchers are currently building a prototype that will be tested in living pigs. We must however wait a while longer until a fully developed medical device is available.