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Microliquid Patterning via Drop Impact
Lee, Minhee; Kim, Ho-Young
In microfluidic technologies, direct patterning of liquid without resorting to micromachined solid structures has various advantages including reduction of the frictional dissipation and the fabrication cost. This fluid dynamics video illustrates the method to micropattern a liquid on a solid surface with drop impact. We experimentally show that a water drop impacting with the wettability-patterned solid retracts fast on the hydrophobic regions while being arrested on the hydrophilic areas.
In this video water is micropatterned on a glass surface which has alternating patterns of hydrophilic and hydrophobic natures. The surface pattern is made by photolithography and selective deposition of decyltrichlorosilane self-assembled monolayers. Water drops with the diameter of 3 mm impacting on the surface at around 3 m/s exhibit aesthetically pleasing patterns while recoiling due to capillary effects guided by the wettability pattern. The drop motions are captured by a high-speed camera at the rates between 2000 and 5130 frames per second.
Microliquid; Patterning; Hydrophilic; Hydrophobic