MICROFLUIDICS

Microfluidics is the science of manipulating and controlling fluids through micro-channels. This type of research requires microminiaturized devices that contain chambers through which fluids flow or are confined. A microfluidic chip enables fluids, down to femtoliters (fL), to be transported, mixed, separated, processed or visualized. Fluids behave differently on a micrometric scale than they do in a normal environment, these unique behaviors are important for scientific research and detailed experiments.

For years, high-speed imaging has been utilized in the following industries for microfluidics research and analysis: Academia, Medical, Biotechnology, Energy, Chemistry, Biology, Pharmaceuticals and more. High-speed cameras have the ability to capture large amounts of data for slow motion analysis.

High speed imaging of micro-sized droplet jetted on surface with wettability pattern

Experimental results based on high speed imaging of micro-sized droplet jetted on a hydrophobic surface with hydrophilic lines are presented. The effects of the hydrophilic line and the initial impact offset distance from the line on the droplet spreading behavior are studied. Two distinct processes have been identified, namely the centering and conforming processes. During the centering process, the droplets which impinge at a certain offset distance from the center of the hydrophilic lines migrate towards the center of the line. A droplet with a larger offset distance experiences a slower centering process. This conforming process involves droplets elongate along the hydrophilic line, causing the droplet to conform to the wettability pattern. The outcome of this study can be applied to inkjet printing process for the enhancement of material deposition accuracy and tolerance of printed micro-sized features.

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Continuous-wave laser generated jets for needle free applications

We designed and built a microfluidic device for the generation of liquid jets produced by thermocavitation. A continuous wave (CW) laser was focused inside a micro-chamber filled with a light-absorbing solution to create a rapidly expanding vapor bubble. The chamber is connected to a micro-channel which focuses and ejects the liquid jet through the exit. The bubble growth and the jet velocity were measured as a function of the devices geometry (channel diameter D and chamber width A). The fastest jets were those for relatively large chamber size with respect to the channel diameter. Elongated and focused jets up to 29 m/s for a channel diameter of [Formula: see text] and chamber size of [Formula: see text] were obtained. The proposed CW laser-based device is potentially a compact option for a practical and commercially feasible needle-free injector.

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Contactless Boiling: A way to improve the reliability of microfluidics process?

The availability of MEMS production techniques allowed the mass production of small sized fluidic systems. The reduced cost price implies that crucial parts of a system become disposable units, improving the serviceability and the controllability. However, small channel diameters demand extra care on fouling, reliability and thermo-mechanical management. In the current investigation, a dedicated setup is realised which aims to obtain contactless boiling due to the presence of a thin gas blanket near the wall. The formation and the possible optimization of this bubbly cushion still needs further research. Understanding of the stability of the thin gas blanket or bubble cushion formation may lead to the demand for novel wall structures which can be realised by means of innovative 3D manufacturing techniques.

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