In this paper we propose a new experimental device for defining and studying self-organized systems, especially those including physical or chemical interactions such as those encountered in collective natural phenomena. We want to be able to reproduce with real robots several paradigms such as stigmergy. In these phenomena the environment stores, diffuses, evaporates chemical substances (pheromones) that drive the behavior of each entity. The proposed device is a smart surface which relies on a graphical environment on top of which robots can move but also read/write information thanks colorimetric sensors and infrared emitters. The surface itself is able to perform some computation, implementing e.g. diffusion/evaporation mechanisms. More generally, the proposed robotic system allows to re-examine theoretical/simulated models in the perspective of defining self-organized robots. We consider in this paper the foraging problem as a case study. In particular we re-examine the expression of the model proposed by Drogoul&Ferber to implement pheromonebased exploration and transport with robots. We then analyze self-organized behaviors, as emergence of chains of robots, and their robustness.