Gecko Adhesion on Flat and Rough Surfaces: Simulations with a Multi-Scale Molecular Model.

Area of Science:

• Biomimetics and Nanotechnology
• Computational Materials Science
• Adhesion Science

Background:

• Gecko spatulae exhibit remarkable adhesion, inspiring biomimetic designs.
• Understanding gecko adhesion requires multiscale modeling due to varying length scales.
• Previous models struggled to accurately predict gecko keratin detachment forces.

Purpose of the Study:

• To develop a particle-based mesoscale gecko spatula model.
• To link atomistic and mesoscale simulations for gecko adhesion studies.
• To investigate spatula detachment from flat and nanostructured surfaces.

Main Methods:

• Developed a particle-based mesoscale gecko spatula model.
• Utilized atomistic molecular simulation results for coarse-graining.
• Performed non-equilibrium simulations to mimic single-spatula detachment.
• Investigated adhesion mechanisms on surfaces with varying roughness.

Main Results:

• The gecko spatula model accurately links atomistic and mesoscale simulations.
• The model correctly simulates the peel-off detachment mechanism.
• Experimental pull-off forces were reproduced by the force field and spatula model.
• Adhesion is determined by the ratio of spatula pad area to the area between surface peaks, not solely root-mean-square roughness.

Conclusions:

• The multiscale gecko spatula model provides a robust framework for studying adhesion.
• The peel-off mechanism is crucial for accurate detachment force prediction.
• Surface topography's accessible area, not just roughness, dictates gecko adhesion.