Development of pulsing surfaces for underwater motion

Biomedical devices, such as catheters or implants, are always sterilized before use to prevent patients from getting an infection. However, during placement, they may inadver- tently be contaminated by microorganisms, resulting in infections once in the body. The goal of this work is to develop a dynamic surface, using a thermoresponsive polymer brush, that will allow to better understand the interaction of bacteria with a dynamic surface and thereby provide new elements to ultimately combat such infections. Although it will not be possible to incorporate the device in the human body as it is, the new understanding of the interaction of bacteria could lead to novel designs of antifouling dynamic surfaces. The surface is covered with a thermoresponsive polymer brush, immersed in water for reproducing physiological conditions, that will be locally heated and thus actuated by an array of electrodes buried just below. Therefore, this master thesis starts by performing finite element simulations for determining the thermal profile in water above the surface. The knowledge of this profile will allow to determine the optimal dimensions, such as the thickness of the different thin films, as well as the current that needs to pass through the electrodes for collapsing locally the thermoresponsive polymer brush. Afterwards, the optimal design determined with the simulations will be fabricated using microfabrication techniques such as photolithography, reactive ion etching, electron beam evaporation, or reactive sputtering. Metrology using ellipsometry, profilometry, and scanning electron microscopy will be regularly used along the process. Finally, it will be shown that spectroscopic and imaging modes of ellipsometry allow to characterize the fabricated dynamic surface in real-time.