Image analysis of axisymmetric droplets in wetting experiments: A new tool for the study of 3D droplet geometry and droplet shape reconstruction

Abstract

A new software tool is developed for droplet image analysis for the study of wetting of solid substrates. The tool extracts information exclusively from images and does not require the use of any properties of the system. Moreover, its applicability covers both axisymmetric and non-axisymmetric droplets. The developed software processes independently droplet images taken from side and top perspectives. Processing of side-view images is made by polynomial fitting to the droplet shape and provides important 2D geometrical features such as contact angles, length, height, contact point coordinates and contour outline. The analysis of top-view images is achieved through active contours (snakes) and yields droplet dimensions, centroid position and contour outline. The combination of synchronized side and top images provides the reconstruction of the droplet 3D shape by means of slices of circular arc shape, which allows estimation of droplet volume and of the distribution of contact angles along its perimeter. The above is an important feature that has not been delivered by other software tools. Experimental results to support the applicability of the new tool are presented for two distinct substrates having different surface properties (glass and Teflon).