Study of the production of drops and their impact on surfaces. Application to the development of an additive manufacturing technique for metals

• Autores: Beatriz Natividad Muñoz Sánchez
• Directores de la Tesis: Alfonso Miguel Gañán Calvo (dir. tes.), José María Montanero Fernández (dir. tes.)
• Lectura: En la Universidad de Sevilla ( España ) en 2021
• Idioma: inglés
• Número de páginas: 119
• Enlaces
  • Tesis en acceso abierto en: Idus
• Resumen

  • Drops are constantlyand spontaneouslyproduced in nature, but varied industrial fields (such as biotechnology, chemical engineering, pharmacy, food industry or microbiology) require dropsto be producedin a controlled manner.Furthermore, many applications in these fields benefit whendroplets arevery smallinsize, on the micrometer and even nanometer scale.Consequently, physics of fluids on the submillimeter scale has been intensively developedin the last decades. Within this area, droplet-based microfluidics has demonstrated to be a leading platform to generate and manipulate a wide range of fluid microentities.On the other hand,the impact of droplets happens to becritically important inmany of the scenarios where they are produced, so this phenomenon should be exploredtogether with droplet delivery.Thisapplication-driventhesis, by compilinga series of8 published articles, addresses the controlled production of droplets by severaldroplet-based methods,and their impact onsurfaces.Paper I produces droplets by both Drop on Demandand direct dripping(gravitational) in order to study their impact over moving liquid surfaces.Since a particularly interesting application is the development of additive manufacturing for metals, Paper II produces droplets in direct jettingmode with that potential use.The next contributions (Paper III, Paper IV and Paper V) aim to generate and characterize PDMS microparticles mainly to develop blood analogue fluids. In this case, needle focusingwas used to produce intermediate-state PDMS precursor droplets that will be later cured into solid particles.A common factor among the aforementioned droplet production techniques is the presence of an orifice or nozzle, which becomesa key element to achieve the fragmentation of a continuous liquid phase into droplets. Therefore, nozzle manufacturing was studiedin this thesis through Paper VI and Paper VII.Finally, the major role played by surface tension at microfluidic scales and its dominance on capillary breakup of jets into droplets requires its value to be accurately known. Paper VIII measures the interfacial tensionbetween two immiscible liquids of similar density, with the consequent application to droplet production methods relying on such value.