Stress-induced tip engineering of micro-hyperbolic structures for enhanced liquid repellency

Area of Science:

• Materials Science
• Surface Engineering
• Nanotechnology

Background:

• Surface functionality of micro- and nanostructured materials is crucial but difficult to tune.
• Existing fabrication methods for fine structural modification are limited in scope and scalability.

Purpose of the Study:

• To develop a facile and scalable method for controlled geometric tuning of micro-hyperbolic structures.
• To investigate the induction of tip bending in micro-hyperbolic structures via metal-specific thin film deposition.
• To explore the resulting surface properties and applications, particularly liquid repellency.

Main Methods:

• Thermal evaporation of metal thin films (gold and aluminum) onto polymeric micro-hyperbolic structures.
• Analysis of residual stress-induced directional tip deformation based on metal properties.
• Application of Stoney's formula to explain bending magnitude in relation to initial taper angle.
• Replication of tip-modified micro-hyperbolic structures for practical applications.

Main Results:

• Controlled tip bending in micro-hyperbolic structures achieved through metal deposition.
• Tensile stress from gold caused bending towards the metal side; compressive stress from aluminum induced bending towards the polymer side.
• Bending magnitude correlated with initial taper angle, consistent with Stoney's formula.
• Tip-modified structures exhibited doubly re-entrant geometries, leading to robust liquid repellency against low-surface-tension liquids.

Conclusions:

• The developed method offers a simplified approach for microscale geometric tuning of surface structures.
• Scalable replication of tip-modified structures is feasible, enabling practical utility.
• Engineered surfaces demonstrate enhanced liquid manipulation and adhesion control capabilities.