fig2 b the volumes 93 and 94 grow in volume but since they are closed volumes the pressure drops and the lumen 1 is pulled towards the membrane 91 by this means the device achieves more friction with the lumen 1 which assists when propagating in slippery surrounding the membrane may be radially segmented as shown in cross sectional views fig2 c and 20d which assists traction if the contact with the lumen 1 is so shaped that it only partially contacts the membrane 91 around its circumference in such a case only some of the segments will be closed since only some of the holes 92 will be in contact with the membrane and hence closed off according to this segmented construction even if parts of the circumferential wall of the lumen do not touch the membrane 91 closure is still affected by other segments and a good grip with the lumen wall is still ensured in a regular colonoscope the ccd camera is preferably located at the tip in this case the camera lens or front viewing window may become dirty from being pushed through and collecting any waste material in the colon furthermore the colon wall is generally collapsed in its regular configuration so that in order to view the colon the area under inspection should be inflated to open it up reference is now made to fig2 a and 21b which illustrate another preferred embodiment of the present invention which enables the device to view the lumen inner wall without getting contaminated the camera 126 is located between two adjacent balloons preferably close to the tip end thus having a clear view of fully opened.