Superhydrophobic surfaces are gaining more and more attention as new applications for them arises. For surface to be superhydrophobic, it has to fulfil two requirements. The static contact angle has to be over 150 degrees but in addition to that, the surface has to have a low contact angle hysteresis. For this reason, measurement of dynamic contact angles is especially important when superhydrophobic surfaces are studied.
There are two main methods for dynamic contact angle measurement; tilting cradle and a so-called needle method. Tilting cradle is fairly often used for dynamic contact angle measurements but can be troublesome for superhydrophobic surfaces. Placing the drop on superhydrophobic surface is somewhat difficult as the drop would prefer to stay in the needle. Also the drop rolls off the image very easily as the contact angle hysteresis is low. For these reasons most of the people prefer the needle method where needle is left in contact with the drop.
Watch the short webinar through the link below to see how contact angle measurements can be done in practice on superhydrophobic surfaces.
Contact lens should support a continuous tear film for optimum visual clarity. It should also resist the sorption of tear components as deposition can lead to decreased visual clarity and discomfort. Wettability of the surface affects both the tear film as well as biocompatibility of the lens.
In industry, wettability is important for example when manufacturing electronics or when planning how to extract oil from the oil reservoir. In all these applications, knowing the contact angle value gives a strong indication on the performance of the product or a successfulness of the process.
Contact angle is easy to understand visually. It is the angle a droplet forms in contact with a solid surface. Thermodynamically, it is a balance between different forces acting on a three-phase contact point where solid, liquid and air meet.