Extremely water-repellent, i.e. superhydrophobic, surfaces display self-cleaning, anti-icing and anti-fogging characteristics, and can be used to reduce viscous drag in liquid flow. Despite the auspicious prospects of superhydrophobicity, methods for measuring wettability and energy dissipation in droplets moving on these surfaces have been insufficient. In this thesis I present the theoretical basis of non-wetting phenomena and review contemporary wetting characterization methods. I also discuss a measuring technique we developed for superhydrophobic surfaces based on magnetically induced oscillations of water-like ferrofluid droplets, which was recently published in Nature Communications. This method can simultaneously measure forces caused by two independent dissipative processes at a precision of ca. 10 nN. One is related to the contact angle hysteresis at the three-phase contact line and the other to viscous dissipation near the droplet-solid contact area. The ability to provide quantitative information about droplet dynamics, inhomogeneities and defects on extremely non-wetting surfaces can make this a useful research and quality control technique for academic and commercial use.
