Instability Key to Mixing Fluids with Markedly Different Viscosities in Microfluidic Devices

Microfluidics is the technology of designing and fabricating devices to manipulate tiny streams of fluids. In the past decade, scientists have developed a variety of microfluidic devices for use in chemical synthesis and biological analysis. These microfluidic devices often utilize an intricate network of channels and reaction chambers to mix different types of fluids at a precise ratio. Many studies assess the mixing performance of microfluidic devices using fluids with similar properties — in real-life applications, however, the properties of fluids used can vary tremendously.

Huanming Xia at the A*STAR Singapore Institute of Manufacturing Technology and co-workers1 have now developed a microfluidic device for mixing fluids with different viscosities. The microfluidic device features a unique network of interconnected channels and circular chambers that triggers instabilities in the fluid flow. These instabilities add up to produce a turbulent flow that dramatically improves the mixing of fluids.

The researchers evaluated the performance of their microfluidic device in mixing glycerol and sodium hydroxide (NaOH), fluids with a 680-fold difference in viscosity. They identified changes in the fluid interface as glycerol and NaOH move along the microfluidic device.

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