Designing Microsystems for biotechnology analysis may be tackled according to two schools of thought: the older, continuous microfluidics, is based on of flows in channels, and digital microfluidics, which is based on droplet handling. The advantages of the latter, which is based on ElectroHydroDynamics and Electrowetting, are emphasized, with a particular focus on its enhanced capacity for integration of elementary fluidic functions into the microsystems. Two planar families of configuration are detailed, namely the opened and the confined. The microsystems achieved are then presented, together with the network of microcatenaries, used for injecting, moving, merging, mixing drops etc. To cite this article: Y. Fouillet, J.-L. Achard, C. R. Physique 5 (2004).