A microfabricated wedge-shaped adhesive array displaying gecko-like dynamic adhesion, directionality and long...

Area of Science:

• Bio-inspired engineering
• Materials science
• Robotics

Background:

• Gecko adhesion is a key model for synthetic adhesives.
• Existing gecko-like synthetic adhesives (GSAs) often lack comprehensive gecko-like performance.
• Simultaneous replication of multiple gecko adhesive features remains a challenge.

Purpose of the Study:

• To develop a novel wedge-shaped GSA that exhibits multiple gecko-like properties concurrently.
• To evaluate the adhesive and shear performance of the GSA during sliding and cyclic loading.
• To investigate the scalability of the GSA for practical applications.

Main Methods:

• Fabrication of square-based wedges (20 µm and 50 µm) using a dual-side, dual-angle lithography process.
• Casting polydimethylsiloxane (PDMS) using SU-8 photoresist molds on quartz wafers.
• Testing adhesive pressure, shear force, and performance retention after 30,000 cycles.

Main Results:

• The GSA demonstrated directional features, zero detachment force, high detachment-to-preload force ratio, and a non-adhesive default state.
• Patches of 1 cm² achieved 5.1 kPa adhesive pressure and supported 17.0 kPa shear.
• After 30,000 cycles, adhesion and shear performance retention was 67% and 76%, respectively, without cleaning.

Conclusions:

• The novel wedge-shaped GSA successfully integrates multiple gecko-like properties, including directional adhesion and robust cyclic performance.
• The GSA offers a non-catastrophic failure mechanism suitable for applications like climbing robots.
• Scalable manufacturing processes enable larger patch sizes with maintained high performance.