The ImageJ software [17] and [18] for the determination of contact angle was used to process the recorded pictures of water drops in the contact with the fingertip surface. This software has two possibilities for drop analysis: Drop Analysis – Low Bond Axisymmetric Drop Analysis, and Drop Analysis – DropSNAKE. The Drop Analysis – Low Bond Axisymmetric Drop Analysis, which is based on the fitting of the Young–Laplace equation to the image data, was used for contact angle measurement of the sessile drops. The inversion point was determined using the Boltzmann equation and the curve of the time-dependent change in the water contact angle.