Working Principle
Droplets are formed using the surface tension properties of liquid. For example, water placed on a hydrophobic surface will lower its contact with the surface by creating drops whose contact angle with the substrate will increase as the hydrophobicity increases. However, in some cases it is possible to control the hydrophobicity of the substrate by using electrical fields. This is referred to as Electrowetting on dielectric or EWOD. In thin layers of Teflon AF, FluoroPel V-polymer or CYTOP, for example, while no field is applied the surface will be extremely hydrophobic and a droplet of water will try to 'stay away' from the surface, resulting in a droplet with steep walls. When a field is applied, a polarized hydrophilic surface is created, and the water droplet tries to 'get closer' to the surface, resulting in much more spread out droplet. By controlling the localization of this polarisation it is possible to control the displacement of the droplet.
Read more about this topic: Digital Microfluidics
Famous quotes containing the words working and/or principle:
“She isn’t harassed. She’s busy, and it’s glamorous to be busy. Indeed, the image of the on- the-go working mother is very like the glamorous image of the busy top executive. The scarcity of the working mother’s time seems like the scarcity of the top executive’s time.... The analogy between the busy working mother and the busy top executive obscures the wage gap between them at work, and their different amounts of backstage support at home.”
—Arlie Hochschild (20th century)
“Now, what I want is, Facts. Teach these boys and girls nothing but Facts. Facts alone are wanted in life. Plant nothing else, and root out everything else. You can only form the minds of reasoning animals upon Facts: nothing else will ever be of any service to them. This is the principle on which I bring up my own children, and this is the principle on which I bring up these children. Stick to Facts, sir!”
—Charles Dickens (1812–1870)