The method of solid-liquid contact angle measurement using the images of sessile drops with shadows on substratum

This paper presents the method of liquid-solid contact angle measurement for the images of sessile droplets, including drop shadows on substratum materials, instead of usual horizontal bottom level lines. ADSA-P trajectory and its skew projection are used to approximate drop profile and shadow boundaries respectively. The intersections of both trajectories determine contact points and localize the bottom line. This implies contact angles between the bottom and profile trajectory.