The PRINTER project proposes to address the development of a new Key Enabling Technology (KET) by demonstrating the proof of concept of a “3D colloidal printer”. The idea is to direct simultaneously the assembly of different nano-objects on a same substrate by coupling an electrostatic directed assembly technique with an original microfluidic chip and set up. To meet the specifications of such method and be able to assemble any type of nanoparticles in 3D, we will study in collaboration with the Nexdot company the production of micropearls, 150-300 nm nanoparticles in which smaller nanoparticles of interests are encapsulated in an Al ₂ O ₃ matrix. Owing to the combination of real time optical observations, numerical simulations and transmission electron microscopy characterizations of the assembly, the 3D co-assembly kinetics of colloidal nanoparticles will be investigated both experimentally and theoretically.