  In the framework of photonics with all-dielectric nanoantennas,
sub-micro-metric spheres can be exploited for a plethora of applications
including vanishing back-scattering, enhanced directivity of a light emitter,
beam steering, and large Purcell factors. Here, the potential of a
high-throughput fabrication method based on aerosol-spray is shown to form
quasi-perfect sub-micrometric spheres of polycrystalline TiO 2 . Spectroscopic
investigation of light scattering from individual particles reveals sharp
resonances in agreement with Mie theory, neat structural colors, and a high
directivity. Owing to the high permittivity and lossless material in use, this
method opens the way toward the implementation of isotropic meta-materials and
forward-directional sources with magnetic responses at visible and near-UV
frequencies, not accessible with conventional Si- and Ge-based Mie resonators.
