Micromachining with short and ultra-short laser pulses has evolved over the past years as a versatile tool that can be employed for the creation of microstructured surfaces. A microstructured surface modiﬁes the way a ﬂuid interacts with a solid surface. Surface microstructuring can then be employed to provide surfaces with certain functionalities. By proper adjustment of the laser machining conditions, well deﬁned surface topographies can be created with suﬃcient accuracy. This allows to investigate the ﬂuid/microstructured surface interactions. However, the relation between the applied laser parameters and the shape of the emerging microstructure has not been systematically studied in literature. This thesis is dedicated to the study of some of the mechanisms underlying diﬀerent ﬂuid/microstructured surface interactions. First, an empirical model is developed for the prediction of the surface topography emerging from a process driven by short laser pulses. To this end, average ablated proﬁles are measured and employed for the simulation of the laser microstructuring pro- cess. The accuracy of the model is assessed by establishing a direct comparison between simulated and measured surface proﬁles. The model is shown to accurately reproduce the surface topography obtained from a laser micromachining process, within a certain processing window. Next, the developed model is employed as a tool for the design of ﬂuidic microstructures, as well as for the investigation of diﬀerent ﬂuidic functionalities, based on the generated microstructures. Moreover, simpliﬁed models are introduced, to relate the geometry of a microstructure to the ﬂuid-microstructure interaction. This allows the calculation of the laser processing parameters that are required to obtain a desired functional microstructured surface. Further- more, modifying key geometrical parameters, for example depths or slopes of the microstructure, allows investigating some of the ﬂuidic mechanisms responsible for the functionality. Hence, additional knowledge on the ﬂuid/microstructured surface interaction is gained by this approach.
|Award date||2 Oct 2014|
|Place of Publication||Enschede|
|Publication status||Published - 2 Oct 2014|