Interfacial tension from height and diameter of a single sessile drop or captive bubble

Abstract The silhouette of a sessile drop submerged in a transparent bulk phase appears to possess a contact angle of 180° with a plane solid support, when the drop is separated from the solid surface by a thin film of surrounding fluid. A computer‐aided analysis of the generalized sessile drop form leads to an explicit equation for interfacial tension dependent only on drop height (from apex to solid support) and the magnitude of the drop equatorial diameter. The equation is valid for a wide range of physically realizable drops. Measurements of drop profile coordinates or the location of the drop equator are not required for the use of the method, leading to improvements in accuracy relative to current practice.