MODELLING OF GLASS MICROSPHERE ASSEMBLY IN A CAPILLARY FLOW CELL FOR PHOTONIC CIRCUIT FABRICATION

Under this grant we propose to develop and validate numerical/mathematical models of the receding fluid edge in a thin tilted flow cell suitable for self-assembly of heavy particles onto waveguide substrates (useful for placement of glass spheres for new optics applications) using the COMSOL Finite Element Multi-Physics Software Package. Under EPSRC grant GR/S96500/01 self-assembly methods have been successfully developed using non-wettable substrates patterned with wettable patches in conjunction with a novel variable tilt and flow rate technique which overcomes the problems associated with sedimentation of heavy particles. Results have demonstrated that the quality of assembly is strongly reliant on the relative positions of the wettable patches together with the global shape and flexibility of the fluid edge throughout assembly. The numerical methods developed under this grant will be validated against the studies conducted under the previous research and will build a capability to rapidly assess the experimental/industrial requirements for the deposition of particles onto patterns of different size, layout and feature density. The model will result in a significant reduction in the number of experiments that would normally be required to define the combination of parameters required for self-assembly, and will provide a design tool which will be useful for aid scientists interested in dewetting of substrates for a range of applications (Self assembly of particles, polymer films, inkjet applications)