Dynamic lateral adhesion force of water droplets on microstructured hydrophobic surfaces

This study investigates the change of the dynamic lateral adhesion forces of water droplets on microstructured surfaces by varying their hydrophobicities. While hydrophobic surfaces showed significant asymmetry in advancing-to-receding profiles, superhydrophobic surfaces did not. As a result, hydrophobic surfaces required greater moving forces at the moment of change of the moving direction than superhydrophobic surfaces. In addition, lateral adhesion forces measured from hydrophobic surfaces were much higher than those from superhydrophobic surfaces. In the present experimental conditions, water droplets did not roll on the surfaces with lateral adhesion forces larger than 21 mgf. These results support the possibility that the rolling ability of a water droplet on a surface can be evaluated by measuring the lateral adhesion force.