Acoustic force measurements on polymer-coated microbubbles in a microfluidic device

This work presents an acoustofluidic device for manipulating coated microbubbles, designed for the simultaneous use of optical and acoustical tweezers. A comprehensive characterization of the acoustic pressure in the device is presented, obtained by the synergic use of different techniques in the range of acoustic frequencies where visual observations showed aggregation of polymer-coated microbubbles. In absence of bubbles, the combined use of laser vibrometry and finite element modelling supported a non-invasive measurement of the acoustic pressure and an enhanced understanding of the system resonances. Calibrated holographic optical tweezers were used for direct measurements of the acoustic forces acting on an isolated microbubble, at low driving pressures, and to confirm the spatial distribution of the acoustic field. This allowed quantitative acoustic pressure measurements by particle tracking, using polystyrene beads, and an evaluation of the related uncertainties. This process facilitated the extension of tracking to microbubbles, which have a negative acoustophoretic contrast factor, allowing acoustic force measurements on bubbles at higher pressures than optical tweezers, highlighting four peaks in the acoustic response of the device. Results and methodologies are relevant to acoustofluidic applications requiring a precise characterization of the acoustic field and, in general, to biomedical applications with microbubbles or deformable particles

Characterization of Trajectories to Collect Samples from Europa's Plume

The search for life in other celestial bodies has always been a topic of great interest within the scientific community. The curiosity to know if we are the only ones in the universe or not has driven the development of many engineering projects. This Master Thesis is meant to do its bit in this research field. Europa, a moon of Jupiter, is thought to have an ocean made of water underneath its icy surface. This ocean could be the perfect environment to find life. The hypotheses of the existence of an ocean gained more strength with the discovery of a water vapour plume in the southern hemisphere of Europa. This plume could be expelling particles from the underneath ocean. The main idea of the project is to design a mission of a pseudo-orbiter (a spacecraft orbiting Jupiter and doing flybys of Europa) which could collect particles from this plume during its flyby trajectory. The objective of this thesis is to determine the maximum number of particles that can be collected with a pseudo-orbiter strategy. To achieve this, first, a plume particle model has been simulated. The outcome of this simulation is a 3D density profile of the water vapour molecules of the plume. The results of this part are needed in order to be able to determine the number of particles that the spacecraft can collect when crossing the plume. After this, the trajectory of the pseudo-orbiter has been designed. The Graphical Method for Same-body Transfers has been used in order to select potential trajectories that could lead to a maximum number of collected particles. This method allows the engineers to identify resonant orbits such that the ground-track of the flyby crosses regions of potential interest. Finally, coupling the two parts of the project has led to the determination of the number of collected particles for the selected trajectories.Aerospace Engineerin

Realidad virtual en el Geoparc Origens: Un museo de puertas abiertas a la Geología de Pirineo catalán

El Geoparque mundial de la UNESCO Orígens, situado en los Pirineos catalanes, alberga paisajes impresionantes y un rico patrimonio geológico, paleontológico y cultural. Sus paisajes cuentan con el reconocimiento internacional de la comunidad científica, que los consideran un laboratorio al aire libre único para el estudio y la comprensión de los procesos geológicos. En consecuencia, geólogos de todo el mundo, ya sean estudiantes, académicos o profesionales, lo visitan todos los años para aprender o investigar temas de diferentes ramas de la Geología