Chemical & Engineering News produced this video of a soft-bodied robot that undulates. The narrator sounds as if she is trying to impersonate the robot:
C&EN gives more details in an accompanying article, which says:
Led by George M. Whitesides, the scientists have constructed an all-polymer robot that can crawl and undulate backward and forward, even navigating obstacles (Proc. Natl. Acad. Sci. USA, DOI:10.1073/pnas.1116564108). Fabricated with soft-lithography techniques used to build microfluidic devices, the robot moves via a series of inflatable chambers embedded between layers of the stretchy commercial elastomer Ecoflex and the more rigid plastic polydimethylsiloxane (C&EN, Feb. 14, page 36). The researchers sequentially inflate the chambers in the arms and spine of the tetrapod robot to propel it along….
(HT Alan Boyle of Cosmic Log)