Molecular and mechanical insights into gecko seta adhesion: multiscale simulations combining molecular dynamics and...

Gecko adhesion, enabled by micro- and nanoscale structures known as setae and spatulae, has prompted extensive research. We present a concurrent multiscale computational model of a seta that integrates molecular dynamics to capture molecular interactions at the spatula-substrate interface and finite element method to simulate the mechanical behavior of the larger setal shaft. This hybrid approach enables synchronized simulations that resolve both fine-scale interfacial dynamics and overall structural deformation. The model reproduces key aspects of spatula behavior during adhesion and detachment, showing that spatula-substrate contact evolves through a combination of bending, sliding, and peeling, depending on the spatula's initial orientation. Our results further demonstrate that lateral sliding can delay detachment, thereby enhancing adhesion strength. The computed pull-off forces and observed mechanisms are consistent with atomic force microscopy measurements and previous simulations. These results align with existing experimental and computational studies. They also overcome scale and resolution limitations inherent in single-scale models.