Principle : Called surface tension or energy of the interface or surface energy the surface tension is a force that exists at any interface between two different media (between a solid or a liquid and a gas). the tension between environments identical: two solids, two liquids, or between a liquid and a solid is usually called the interfacial tension.
it is this force, the surface tension, which allows the water drop does not spread on a sheet, or some insects to walk on water.
the surface tension is very important especially in industrial processes. the higher it is, the more the adhesion of a substance (glue, ink) is applied on the material will be good.
the angle measurement of a droplet allows you to assess simply the wettability of the surfaces, directly related to their surface energy.
the principle of operation is quite simple: a camera allows you to raise the profile of the drop placed on the substrate using a syringe and a mobile platform. the software operating on the computer allows the automatic extraction of the contact angle, using different algorithms.