F Schönfeld | PubMed Health

PubMed2006

Electroosmotic flow patterning using microfluidic delay loops.

A theoretical and experimental investigation of alternating electroosmotic flow patterns by means of specially designed delay loops is presented. Using elementary methods of compact network modeling and detailed FEM simulations the flow behavior and, in particular, the rearrangement of sample plugs is modeled. The proposed designs rely on flow splitting in combination with electroosmotic delay loops leading to a runtime difference or phase shift between two sub-streams. Due to this phase shift, a new fluid interface is generated at the merging point. The approach is experimentally validated by injection of a Rhodamine 6G solution into an aqueous sodium tetraborate buffer.

Borates↗

PubMed2004

An optimised split-and-recombine micro-mixer with uniform chaotic mixing.

A second generation micro-mixer, being a further optimised version of a first prototype, relying on the consequent utilisation of the split-and-recombine principle is presented. We show that the mixing can be characterized by a positive finite-time Lyapunov exponent although being highly regular and uniform. Using computational fluid dynamics (CFD) we investigate the mixing performance for Reynolds numbers in the range of about 1 to about 100. In particular for low Reynolds numbers (Re < 15) the CFD results predict an almost ideal multi-lamination. Thus, the developed mixer is especially suited for efficient mixing of highly viscous fluids. Furthermore, the numerical results are experimentally validated by investigations of mixing of water-glycerol solutions. The experimental results are found to be in excellent agreement with the numerical data and prove the high mixing efficiency.

Journal Article↗