Olivieri, Federico (2018) Manipulation of polymeric fluids through pyro-electro-hydro-dynamics. [Tesi di dottorato]

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This thesis is focused on the manipulation of liquids and polymeric fluids in a non-contact and electrode-free way, exploiting pyro-electro-hydro-dynamic systems. The thesis structure provides an introduction based on the theory and the combination between pyroelectric and electro-hydro-dynamic effect, with a focus on the developed techniques, followed by the presentation of the realized works. It will be presented the fabrication of micro-optical devices, in particular micro-lenses, through pyro-electro-hydro-dynamic effect. The attention will be directed toward the fabrication methods: in fact, they have been obtained by an ink-jet technology or through self-assembly on a micro-engineered pyroelectric crystal. In the first case, a new pyro-ink-jet set-up will be proposed and further modifications of the set-up, which will improve the flexibility of the technique, will be reported. The realized micro-lenses will be optically and geometrically characterized and it will be presented the fabrication of a multi-component device as an example of application of this technique. It will be shown that pyro-ink-jet printing permit to realize very uniform micro-lenses arrays with high resolution (diameter ̴ 300 nm). The second approach is based on the self-assembly of a micro-lenses array on a micro-engineered pyroelectric crystal. It will be showed an array decoration by nano-particles, such as quantum dots, and it will be presented the di-electro-phoretic effect on the employed dots. In particular, the study will focus on the effect of the patterned substrate on the localization of the nano-particles and on the investigation of the dots pattern transfer. Moreover, it will be shown another application of pyro-ink-jet printing: the capability of this system in the highly viscous solution manipulation allows the deposition of polymeric fibers and, in particular, how a fiber like these can be used as a component in a microfluidic channel. That demonstrates pyro-ink-jet printer is also an alternative to the classic electro-spinning system, avoiding electrodes and spiraling effect during the deposition. Produced fibers show great uniformity and reach thicknesses until the nano-metric scale. Moreover, there will be illustrated all the procedures realized to produce the micro-channel.

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