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En esta Tesis Doctoral Industrial se estudia la problemática del diseño de un sistema de deposición de pulverización catódica en geometría de ángulo oblicuo en escalas y condiciones industriales para operar sobre superficies rugosas de grado industrial. Esta técnica, de amplio uso, se suele utilizar para hacer recubrimientos de tipo compacto en su geometría clásica, mientras que su uso a ángulo oblicuo, responsable del crecimiento nanocolumnar, está restringido a laboratorios de investigación debido a las numerosas restricciones que impone dicha geometría de trabajo, e. g. inhomogeneidad de los recubrimientos, dificultad para producción en serie, imposibilidad de operar sobre grandes superficies, etc. En pequeñas superficies, los recubrimientos nanocolumnares son bien conocidos por poseer propiedades singulares asociadas a su baja densidad y a la alta superficie específica de las nanocolumnas. Es por esto que el desarrollo de esta técnica en escalas operativas industriales resulta clave para su incorporación en diferentes dispositivos tecnológicos y para el desarrollo de aplicaciones basadas en ellas..., This industrial PhD Thesis aims at studying the problems associated with the design of a magnetron sputtering reactor to operate at oblique angle geometries over large industrial rough substrates. This technique, in its classical non-oblique configuration, is widely employed in research laboratories and in the industry to coat large surfaces with compact homogeneous thin films. Yet, the use of the oblique angle configuration is currently constrained to conditions found in research laboratories, such as the requirement of small-scale and ultrasmooth flat substrates. Also, some consequences of the use of this configuration, e.g. thin film inhomogeneity, or the impossibility to operate on roll-to-roll systems, for instance, have prevented until now its implementation at industrial scales. On small laboratory-size substrates, the films produced at oblique geometries are formed by a disordered array of tilted nanocolumns, with diameter ~100 nm and separated side-to-side a similar distance. This gives these films high porosity, low density, and high specific surface, which confer them unique and remarkable properties, with applications in fields as different as sensors, optics, microelectronics, optoelectronics, plasmonics, microfluidics, etc. Consequently, the development of a clear strategy to grow this type of films at industrial scales represents a fundamental key challenge to develop/improve numerous state of the art technological devices...

It is demonstrated that, besides classical nanocolumnar arrays, the oblique angle geometry induces the growth of singular structures in the nanoscale when using wisely designed patterned substrates. Well-ordered array of crosses, cylindrical nanorods or hole structures arranged in square or hexagonal regular geometries are reported as examples, among others. The fundamental framework connecting substrate topography and film growth at oblique angles is presented, allowing the use of substrate patterning as a feasible thin film nanostructuring technique. A systematic analysis of the growth of TiO2 thin films on 4 different lithographic patterned substrates in 4 different scale lengths is also presented. A first conclusion is the existence of a height-based selective growth in the initial stages of the deposition, by which the film preferentially develops on top of the tallest substrate features. This behavior is maintained until the film reaches a critical thickness, the so-called Oblivion Thickness, above which the film topography becomes gradually independent of the substrate features. A general formula relating the spatial features of the pattern, the coarsening exponent and the Oblivion Thickness has been deduced.

It is demonstrated that, besides classical nanocolumnar arrays, the oblique angle geometry induces the growth of singular structures in the nanoscale when using wisely designed patterned substrates. Well-ordered array of crosses, cylindrical nanorods or hole structures arranged in square or hexagonal regular geometries are reported as examples, among others. The fundamental framework connecting substrate topography and film growth at oblique angles is presented, allowing the use of substrate patterning as a feasible thin film nanostructuring technique. A systematic analysis of the growth of TiO2 thin films on 4 different lithographic patterned substrates in 4 different scale lengths is also presented. A first conclusion is the existence of a height-based selective growth in the initial stages of the deposition, by which the film preferentially develops on top of the tallest substrate features. This behavior is maintained until the film reaches a critical thickness, the so-called Oblivion Thickness, above which the film topography becomes gradually independent of the substrate features. A general formula relating the spatial features of the pattern, the coarsening exponent and the Oblivion Thickness has been deduced.

Addressing the problem of infection from the very first stage, i.e. inhibiting the formation of the bacterial biofilm, is a crucial step to prevent implant rejection. Nanocolumnar coatings exhibiting antibacterial properties have been fabricated by oblique deposition with magnetron sputtering [1]. The formation of nanocolumns (Fig.1) is the result of the effects of atomic shadowing when the atoms reach the surface along an inclined direction [2]. This technique is environmentally friendly: it is carried out at RT and does not involve chemical products (no recycling problems). Such methodology have been tested in a semiindustrial scale reactor, successfully coating in a single step the two sides of fixation plates for bone fractures [3]. Several in vitro experiments have been performed: analysis of bacterial adhesion and biofilm formation, analysis of osteoblast proliferation and mitochondrial activity, and osteoblasts–bacteria competitive growth scenarios, the latter also named “Race for the Surface” competition. In all these cases, the coatings show an opposite behavior toward osteoblast and bacterial proliferation [1,3]. Moreover, they are effective against Gram positive (S. aureus) and Gram negative (E. coli) bacteria [4]. Finally, when a synergic route is followed and the coatings are functionalized with Te nanorods, the antibacterial properties are enhanced, since Te adds contact-killing (Fig. 2), i.e. bactericidal effect, whilst the biocompatibility is preserved [4].

RESEARCHER ID M-9921-2014 (Isabel Izquierdo Barba) ORCID 0000-0002-4139-4646 (Isabel Izquierdo Barba) RESEARCHER ID L-6167-2014 (Daniel Arcos Navarrete) ORCID 0000-0002-5367-7272 (Daniel Arcos Navarrete) RESEARCHER ID M-3378-2014 (María Vallet Regí) ORCID 0000-0002-6104-4889 (María Vallet Regí), Based on an already tested laboratory procedure, a new magnetron sputtering methodology to simultaneously coat two-sides of large area implants (up to ~15 cm2) with Ti nanocolumns in industrial reactors has been developed. By analyzing the required growth conditions in a laboratory setup, a new geometry and methodology have been proposed and tested in a semi-industrial scale reactor. A bone plate (Depuy Synthes) and a pseudo-rectangular bone plate extracted from a patient have been coated following the new methodology, obtaining that their osteoblast proliferation efficiency and antibacterial functionality were equivalent to the coatings grown in the laboratory reactor on small areas. In particular, two kinds of experiments have been performed: analysis of bacterial adhesion and biofilm formation, and osteoblasts-bacteria competitive in vitro growth scenarios. In all these cases, the coatings show an opposite behavior towards osteoblast and bacterial proliferation, demonstrating that the proposed methodology represents a valid approach for industrial production and practical application of nanostructured titanium coatings., Unión Europea. H2020, Ministerio de Economía y Competitividad (MINECO)/FEDER, Comunidad de Madrid, Depto. de Química en Ciencias Farmacéuticas, Fac. de Farmacia, TRUE, pub

Based on an already tested laboratory procedure, a new magnetron sputtering methodology to simultaneously coat two-sides of large area implants (up to ~15 cm2) with Ti nanocolumns in industrial reactors has been developed. By analyzing the required growth conditions in a laboratory setup, a new geometry and methodology have been proposed and tested in a semi-industrial scale reactor. A bone plate (DePuy Synthes) and a pseudo-rectangular bone plate extracted from a patient were coated following the new methodology, obtaining that their osteoblast proliferation efficiency and antibacterial functionality were equivalent to the coatings grown in the laboratory reactor on small areas. In particular, two kinds of experiments were performed: Analysis of bacterial adhesion and biofilm formation, and osteoblasts–bacteria competitive in vitro growth scenarios. In all these cases, the coatings show an opposite behavior toward osteoblast and bacterial proliferation, demonstrating that the proposed methodology represents a valid approach for industrial production and practical application of nanostructured titanium coatings.

The influence of one dimensional substrate patterns on the nanocolumnar growth of thin films deposited by magnetron sputtering at oblique angles is theoretically and experimentally studied. A well‐established growth model has been used to study the interplay between the substrate topography and the thin film morphology. A critical thickness has been defined, below which the columnar growth is modulated by the substrate topography, while for thicknesses above, the impact of substrate features is progressively lost in two stages; first columns grown on taller features take over neighboring ones, and later the film morphology evolves independently of substrate features. These results have been experimentally tested by analyzing the nanocolumnar growth of SiO2 thin films on ion‐induced patterned substrates.

Based on an already tested laboratory procedure, a new magnetron sputtering methodology to simultaneously coat two-sides of large area implants (up to ~15 cm2) with Ti nanocolumns in industrial reactors has been developed. By analyzing the required growth conditions in a laboratory setup, a new geometry and methodology have been proposed and tested in a semi-industrial scale reactor. A bone plate (DePuy Synthes) and a pseudo-rectangular bone plate extracted from a patient were coated following the new methodology, obtaining that their osteoblast proliferation efficiency and antibacterial functionality were equivalent to the coatings grown in the laboratory reactor on small areas. In particular, two kinds of experiments were performed: Analysis of bacterial adhesion and biofilm formation, and osteoblasts–bacteria competitive in vitro growth scenarios. In all these cases, the coatings show an opposite behavior toward osteoblast and bacterial proliferation, demonstrating that the proposed methodology represents a valid approach for industrial production and practical application of nanostructured titanium coatings.