Gecko-Inspired Dry Adhesive Based on Micro-Nanoscale Hierarchical Arrays for Application in Climbing Devices

Area of Science:

• Biomimetics and Materials Science
• Robotics and Adhesion Technology

Background:

• Geckos exhibit remarkable climbing ability due to hierarchical structures and stiff β-keratin in their toe pads.
• Replicating gecko adhesion in engineered dry adhesives is challenging due to difficulties in fabricating high-aspect-ratio structures with stiff polymers.

Purpose of the Study:

• To develop a method for fabricating high-aspect-ratio hierarchical arrays using a stiff polymer.
• To evaluate the adhesive performance and durability of the fabricated structures.
• To demonstrate the application of these dry adhesives in a miniature robotic system.

Main Methods:

• Utilized a sacrificial-layer-mediated nanoimprinting technique to create high-aspect-ratio hierarchical arrays on polycarbonate sheets.
• Tested shear adhesion strength and cyclic durability of the dry-adhesive films.
• Integrated the fabricated arrays onto the feet of a miniature robot for locomotion tests.

Main Results:

• Achieved formidable shear adhesion of 11.91 ± 0.43 N/cm² with the fabricated dry-adhesive films.
• Demonstrated excellent durability, with adhesion reducing only ~20% after 50 cycles and remaining stable up to 200 cycles.
• Successfully integrated the hierarchical arrays onto a miniature robot, enabling locomotion on a 30° inclined surface.

Conclusions:

• The sacrificial-layer-mediated nanoimprinting technique effectively produces high-aspect-ratio hierarchical structures with stiff materials, mimicking gecko adhesion.
• The developed dry adhesives exhibit strong and durable adhesion, suitable for demanding applications.
• The successful integration into a miniature robot highlights the potential of this technology for advanced locomotion systems.