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11-04 :: April/May 2011

nanotimes News in Brief

Drop Emission // Controlled Production of Nanometric Drops

R

esearchers from the Faculty of Physics at the University of Barcelona, Spain, have carried

out a study in which they demonstrate the physical conditions required for the controlled production of drops between the micro- and nanoscales.

According to Aurora Hernández-Machado, a lec- turer with the UB’s Department of Structure and Constituents of Matter and co-author of the study, “miniaturization in liquids is important in increasing efficiency and optimizing the rate of consumption of substances such as pharmaceutical products, cos- metics and ink, which would enable us to lower the cost of processes associated with the production and control of these products. In addition, the physical model, which we could define as a microfluidic dis- penser for various substances, allows us to overcome the limitations traditionally associated with drop for- mation processes and to create submicrometre-scale droplets”.

The researchers have been able to establish the balance of forces that determines the drop emission mechanism, which involves the capillarity of the flu- id, the viscous friction of the solid surface and gravity. This balance and the size of the liquid filaments determine the size of the drops emitted, which in some cases are nanometric. It has also been observed that the emission of drops depends to a great extent on the static wetting angle, that is, the angle that the

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drop makes with the contact surface. The greater this angle the higher the degree of hydrophobia of the surface in question.

Image: The experiments carried out for the study, focusing on water in air, the team of researchers has demonstrated the operation of the microfluidic model and created drops at the micrometre scale, but the model is also capable of producing nanometric droplets. © UB

Rodrigo Ledesma-Aguilar, Raul Nistal, Aurora Hernández- Machado e Ignasi Pagonabarraga: Controlled drop emis- sion by wetting properties in driven liquid filaments, In: Nature Materials, Nature Materials, Vol. 10(2011), No. 5, May 2011, Pages 367-371, DOI:10.1038/NMAT2998: http://dx.doi.org/10.1038/NMAT2998

http://www.ub.edu

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