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Updated: Mar 24, 2026

Measuring the Interaction Force Between a Droplet and a Super-hydrophobic Substrate by the Optical Lever Method
Published on: June 14, 2019
Force of adhesion on supersolvophobic surfaces: The role of capillary necks
Juan V Escobar1, Rolando Castillo1
1Instituto de Física, Universidad Nacional Autónoma de México, P.O. Box 20-364, Mexico City 01000, Mexico.
Abstract:
We study theoretically the force of adhesion of pinned liquid drops in contact with supersolvophobic surfaces. We develop a method to calculate the contact and excess surface areas vs compression of the drops against surfaces characterized by an effective interfacial energy in the Cassie-Baxter wetting regime. We find that a 9° difference in contact angle can increase the force of adhesion by almost three orders of magnitude. We investigate the role that the inevitable formation of capillary necks has on this force, which has the same functional form of Derjaguin's result for elastic solids. Our results suggest that measuring the force of adhesion directly on nearly perfectly solvophobic surfaces may be a more precise technique to quantify the effective interfacial energy than traditional contact angle measurements on macroscopic drops.
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