One of our current research interest in Applied Optics is focused on the integration of nanostructures and nanomaterials with diffractive optical elements. In the recent years, we have witnessed a growing activity to expand the optical shop portfolio by complementing the refractive (or reflective) classical optics, and the diffractive optics, with a new approach that is based on the full electromagnetic interaction of light with subwavelength structures. This addition has been named as resonant optics, or flat optics. It provides optical devices with resonant optical elements having a response related with the material characteristics and strongly dependent on the geometry. Our first approach has been the modeling and computational analysis of the interaction of these elements for a variety of applications in biomedical sensing, and industrial metrology. Since our laboratories are not equipped with high-cost nanofabrication facilities, we are applying low-cost nanostructuring techniques to compare the results with those elements manufactured with electron beam lithography and other commonly used nanofabrication tools. At the same time, our research activity continuously use the specialized fabrication and testing services of the Complutense University (electron-microscopy, laser ablation processing, etc.).The proposed merging of nanophotonic structures and concepts with microoptics and diffractive optical elements will be applied to practical devices. As an example, our recent advances in the integration of nanostructures with solar cells, has made possible to propose refractometric sensors fully interrogated using the optoelectronic response of the devices.