A Novel Bioinspired Switchable Adhesive with Three Distinct Adhesive States

Area of Science:

• Materials Science
• Biomimetics
• Surface Engineering

Background:

• Gecko feet exhibit remarkable dry adhesion through hierarchical fibrillar structures.
• Developing synthetic materials that mimic gecko adhesion is crucial for advanced attachment technologies.
• Controlling adhesion strength dynamically remains a significant challenge in synthetic dry adhesives.

Purpose of the Study:

• To introduce a novel switchable adhesive inspired by gecko's fibrillar dry attachment system.
• To demonstrate a two-step control mechanism for adhesion force based on preload.
• To develop a new fabrication method for creating multi-height pillar structures.

Main Methods:

• Fabrication of a patterned surface with mushroom-shaped pillars of two distinct heights using a novel 'double inking' method.
• Analysis of adhesion performance under varying preload conditions.
• Investigation of pillar deformation behavior using in situ monitoring.

Main Results:

• The adhesive exhibits two distinct levels of pull-off force controlled by low and high preload.
• Low preload engages only taller pillars for lower adhesion; higher preload engages all pillars for stronger adhesion.
• Excessive loading induces buckling, leading to a significant decrease in pull-off force, demonstrating switchable adhesion.

Conclusions:

• The developed gecko-inspired adhesive offers tunable adhesion with a two-step switching mechanism.
• The 'double inking' fabrication method successfully creates the required multi-height pillar structures.
• This technology has potential applications in areas requiring switchable and controllable dry adhesion.