Contact angle measurement

Contact angle measurements can be done on flat surfaces to determine its hydrophobic or hydrophilic behavior. A total of 10 drops will be placed on the to be measured surface which are then imaged by a camera. Via the software the contact angle at the left and right size is than calculated, and gives an average over the 10 droplets. With contact angle measurements a variation of +/- 3° in between measurements is within the tolerance limits.