Sessile Drop

The sessile drop is the standard arrangement for optical measurement of the contact angle using drop shape analysis.

Sessile drop and its reflection on the surface of a solid

In the case of the static contact angle, the deposited drop lies on the surface of a solid.

In the case of the dynamic contact angle, the size of the drop is increased (advancing angle) or reduced (receding angle) during the measurement by means of a needle immersed in the drop, or moved over the solid with the help of a tilting table.