A self-propelled device for locomotion through a lumen, comprising a set ofserially arranged inflatable chambers, the end ones of which expand at leastradially when inflated. Connecting passages provide fluid communicationbetween each pair of adjacent chambers. A fluid source is attached to one ofthe end chambers. The connecting passages are such that the fluid inflates thechambers in a sequence, beginning with the chamber closest to the source, andending with the chamber furthest from the source. The same sequence occurswhen the chambers deflate, beginning with the chamber closest to the source,and ending with the chamber furthest from the source. The fluid source caneither be a fluid supply tube, extending to a supply outside the lumen, or itcan be built-in and carried by the device. The device can crawl either alongthe lumen wall or on an inserted guide wire.
