Estimation of Size and Contact Angle of Evaporating Sessile Liquid Drops Using Texture Analysis

Abstract

Size and contact angle of liquid drops are fundamental parameters in interfacial science. Accurate estimation of these parameters can provide objective information regarding several properties of the contacting surface. We leveraged principles of texture analysis to estimate the contact angle and the drop diameter from videos of evaporating sessile liquid drops deposited on solid surfaces. Specifically, we used a Harris corner detector to locate the corners and dynamically estimate the changing size and a Gabor wavelet-based approach to estimate the varying contact angle of the evaporating sessile drop. We demonstrated the ability of our approach to accurately estimate size and contact angles of drops deposited on a hydrophilic glass slide and on a paraffin film representing a hydrophobic surface. We also estimated the contact angle and size of drops deposited on horizontal and tilted surfaces to generate symmetric and asymmetric drop shapes, respectively. A software application that has the ability to analyze videos of sessile liquid drops as inputs is provided, and this tool can generate plots of the estimated contact angle and the drop diameter as a function of frame number.