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Microfluidics Software simulates wetting behaviour of liquids

| Redakteur: Kathrin Schäfer

Certain aspects of microfluidic systems used in the medical laboratory could be simpler with surfaces that repelled water and other liquids. New simulation software developed at the Fraunhofer Institute of Material Mechanics IWM in Freiburg helps determine how such surfaces should look.

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Left: A micron-thin structured polystyrene surface for microfluidic applications. Right: Static wetting of a surface of this type with water—simulation and experiment.
Left: A micron-thin structured polystyrene surface for microfluidic applications. Right: Static wetting of a surface of this type with water—simulation and experiment.
(Bild: FraunhoferIWM)

To analyse tissue cells or DNA components, physicians often use microfluidic systems such as throughflow cuvettes.

Drop residues falsify laboratory findings

The liquid containing dissolved substances flows through tiny channels and small chambers and is analysed as it does so. It is important that this fluid be able to be removed from all chambers and channels following analysis without leaving any residues, because residual droplets would blend with the next sample and falsify the findings pertaining to it.

Optimizing microfluidic systems

What qualities must surfaces have in order optimally to self-clean? This is what the simulation software developed by the Fraunhofer IWM researchers calculates. The simulation is intended to help optimise microfluidic systems and support the design of surfaces that will retain as little liquid as possible.

“Our aim is to better understand and specifically control the wetting behaviour of liquids on structured surfaces,” says Dr Adham Hashibon, project manager at the Fraunhofer IWM. But that isn’t all: the tool can also help realise a type of traffic conduction system in microfluidic systems. If each of the channels continuing beyond a fork in the path is equipped with unique surface structures, different components in the sample can be separated: for example, DNA molecules may flow into one channel and other components into the other. This allows the concentration of certain molecules to be increased in a targeted fashion, which is particularly important for enhancing an analytical method’s trace sensitivity.

Simulating drop shape and flow behaviour

One thing the program does is to simulate the shape assumed by drops of liquid on the channel or chamber surface and thus, for example, determine whether the liquid spreads across the surface or contracts into beads in order to minimise contact with it. In addition, it calculates flow behaviour and, consequently, the way in which liquids move along various types of surface.

For further information:

Fraunhofer-Institut für Werkstoffmechanik IWM

Freiburg, Germany

www.iwm.fraunhofer.de

(ID:34161710)