High-rate production of functional nanostructured films and devices by coupling flame spray pyrolysis with supersonic expansion.

The fabrication of functional thin films and devices by direct deposition of nanoparticles from the gas phase is a promising approach enabling, for instance, the integration of complex analytical and sensing capabilities on microfabricated platforms. Aerosol-based techniques ensure large-scale nanoparticle production and they are potentially suited for this goal. However, they are not adequate in terms of fine control over the lateral resolution of the coatings, mild processing conditions (avoiding high temperature and aggressive chemicals), low contamination and compatibility with microfabrication processes. Here we report the high-rate and efficient production of functional nanostructured films by nanoparticle assembling obtained by the combination of flame spray pyrolysis and supersonic expansion. Our approach merges the advantages of flame spray pyrolysis for bulk nanopowders such as process stability and wide material library availability with those of supersonic cluster beam deposition in terms of lateral resolution and of direct integration of nanomaterials on devices. We efficiently produced nanostructured films and devices (such as gas sensors) using metal oxide, pure noble metal and oxide-supported noble metal nanoparticles.

Supersonic cluster beam deposition of nanostructured thin films with uniform thickness via continuously graded exposure control.

Supersonic cluster beam deposition is a powerful technique for the production of nanostructured thin films and the microfabrication with stencil masks of patterns with very good lateral resolution. The high focusing of cluster beam typical of supersonic expansions causes the deposition of films with strong thickness variation over a small area. To overcome this problem we have designed and tested a rotating screen allowing a continuously graded exposure of the substrate during cluster beam deposition. This allows the production of nanostructured films with uniform thickness over a large area while keeping all the features typical of supersonic beams.

Adhesion and proliferation of fibroblasts on cluster-assembled nanostructured carbon films: the role of surface morphology.

We have investigated the influence on adhesion and proliferation of NIH 3T3 fibroblasts of the surface morphology of cluster assembled carbon films deposited by Supersonic Cluster Beam Deposition. Nanostructured carbon films exhibit a multi-scale morphology, which resembles the surface structure of the extracellular matrix, and possess a high specific area, while being relatively smooth at all scales. Correlations between measured morphological parameters and adaptive cell response have been brought out. High specific area and smoothness appear to conceivably favour both the early attachment of plated cells and the long-term survival of adherent cells. Moreover, nano-structured carbon films affect the cells morphology as well as the extension and the number of the focal contacts.