Functional TiO2, ZnO, SiO2 and doped SnO2 in the form of porous thin films and other supported fiber-like nanostructures will be prepared by plasma deposition and evaporation at glancing angles (GLAD). Precise control of the nano and microstructure of the films and fibers will be attained by selecting appropriate GLAD deposition conditions and, in the case of plasma deposition, by adjusting the principal plasma parameters after modelling the plasma processes and sheath-related phenomena that control the development of the film/fibers nanostructure. The primary objective of the project is to successfully tailor the porosity and other key properties (optical, electrical conductivity, wetting behaviour etc.) of the synthetized materials to enable novel methods of fluid handling (liquids and gases) at the micro and, possibly, nanoscales so as to invent and develop applications in the fields of microfluidic and microplasmas.
A further objective is the processing of these structures in both 2D (i.e., lithographic processsing) and 3D by use of laser-based techniques, multilayer stacking of different porous thin film structures and/or selected plasma deposition of hydrophobic patches of other materials such as polymers, silicones, etc. Microfluidic thin film-based devices controlled by light (i.e., photonic valves) will then be developed by employing appropriately designed TiO2 and ZnO porous structures. These materials become superhydrophilic when illuminated with light of <390 nm which will be used to selectively illuminate very small areas (channels, micrometer circuits, etc.) by either a suitable lamp or a laser. Light-controlled microfiltration is envisaged as another new application in this field, whereby preferential diffusion/filtration of polar liquids through the illuminated zones may be induced (i.e. valve open). Achieving prompt reversal of this process (i.e. valve closed) is another challenge that will be addressed by the project.
A final, exploratory objective is the modelling, design and development of microplas-mas based on the most promising thin film porous structures developed during the earlier phases of the work. These prototype microplasma devices will consist of porous doped SnO2 thin film electrodes permeable to gases with porous insulator layers (SiO2) acting as separation barriers. Evaluation of the plasma characteristics of these prototype devices will be another distinct task undertaken by the project.