2008 NSTI Nanotechnology Conference and Trade Show - Nanotech 2008 - 11th Annual

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TechConnect Summit
Clean Technology 2008

Computational Microfluidics for Miniaturised Bio-Diagnostics Devices using the code “TransAT”

C. Narayanan, D. Lakehal
ASCOMP GmbH, CH

Keywords:
microfluidics, free-surface flow, phase-change, Marangoni, electric effects

Abstract:
We will report on our recent advances made in predicting this class of flows with our CMFD code TransAT (www.ascomp.ch), using the Level Set approach as an “Interface Tracking Method”. Our code incorporate phase-change capabilities, surface tension and triple-line dynamics models, Marangoni effects due to variable surface tension coefficient with temperature, and electric and magnetic fields, which can also be used to control the dynamics of micro-droplets in the channels, and a near-wall, micro-film sub-grid model for lubrication. As bio-chips may generally comprise various components (multi-channelled, multiple components, complex configurations), we have developed a new fully automatized version for microfluidics applications in bio-devices, using the IST (Immersed surfaces Technique) technique to map complex components/geometries into a simple rectangular Cartesian grid. Near wall regions are treated by another new feature, namely the BMR (Block-based Mesh Refinement), in which sub-scale refined blocks are placed around each structure or obstructions, up to 4 levels of refinement. The connectivity between blocks can be achieved in parallel (using MPI) up to 8-to-1 cell mapping. The combination IST/BMR can save up to 70% grid cells in 3D. In this paper we will focus on the role played by the Marangoni effects in controlling the dynamics of micro-droplets in bio-chips. We will also show how similar effects can be obtained by applying an external electric or magnetic field, the effect of which is taken into account by the model.


Nanotech 2008 Conference Program Abstract