This paper describes the design of a novel miniaturised robot mimicking the locomotion mechanism of polychaete worms. The robot architecture is bio-inspired and for designing purposes a modular approach has been followed. The robot consists of independent modules which move like polychaete worm segments, generating a transversal sinusoidal wave along the body. In order to reproduce this undulatory locomotion pattern, the specific bending movement of Ionic Polymer-Metal Composite (IPMC) material in response to electric stimuli has been considered. Each module consists of a strip of IPMC and two mechanical clamps able to establish electrical contact with the polymer and to mechanically join in series different strips. A 4-module prototype has been fabricated with an external control. By means of software interface different modules activation sequences could be implemented. Initial results and considerations are reported