Abstract : This thesis presents various applications of radical photopolymerization in microfluidic chips. In a first part, we describe the interest and importance of surface modification rendering the surface of microfluidic channels hydrophilic and neutral. We present surfaces modifications based on radical photopolymerization of polyacrylamide, first in PDMS chips, in which it is a challenge to obtain stable coatings and then on COC surface which is chemically inert. In an other application, photopolymerization is developed for MEMS in-situ implementation in microchannels. We present the integration of arrays of columns functionalized with proteins, as well as flow sensors. A flow sensor based on the elongation of a deformable structure showed a large range of measurable flow range, good sensibility and reproducibility. The second flow sensor measurement principle is based on the rotation of a structure around an axel. Although it has lower performances, its measurement does not depend on fluid's viscosity.