Direct patterning of PDMS films is achieved by modulating the wettability of polar dielectric substrates. Periodic array structures of microbumps can be madeup by functionalizing periodically poled lithium niobate crystals. The modulation of surface wettability is obtained through the spatial distribution of the surface electric charges generated by the pyroelectric effect under electrode-less configuration. An appropriate thermal treatment of the substrates assures both the wettability patterning and the fast cross-linking of the PDMS film.