The creation of drops in T-shaped microfluidic devices with the ‘modified’ laser–LIGA technique: I. Fabrication

Abstract

Surface effects are crucial in multiphase microfluidics, particularly in drop creation, where solid surface properties are a determining factor ill a successful creation of micro- and nanodrops. Often, drops cannot be created due to the modification of solid Surface properties as a result of the chosen micro fabrication method. A novel micrornachining technique is demonstrated, which combines nickel template fabrication and replication of microstructures on polymer substrates for mass production of microfluidic devices. The 'modified' laser-LIGA technique eliminates Surface wetting problems and the Occurrence of a deeperjoint section resulting from traditional excimer laser ablation based methods. It is shown in this work that monodisperse microdrops can be successfully created in T-shaped microchannels fabricated with this technique. An investigation of shear-induced drop formation from the resulting, T-shaped fluidic devices has shown that drop size decreases with increasing shear and that there exists a maximum in drop productivity for a given dispersed phase flowrate. The experimental data can be produced with high levels of certainty and repeatability, which again demonstrates the robustness of this technique.