Residue-free peeling of EGaIn oxide enabled by contact angle control

Area of Science:

• Materials Science
• Soft Robotics
• Nanotechnology

Background:

• Gallium-based liquid metals (GBLMs) are essential for soft machines and stretchable electronics.
• Their native oxide layer causes strong adhesion, hindering residue-free removal and limiting applications.
• Current removal methods often involve harsh chemicals, posing practical challenges.

Purpose of the Study:

• To develop a non-destructive method for removing GBLM oxide layers.
• To understand the interfacial mechanics governing GBLM delamination.
• To improve the controllability of liquid metal-based technologies.

Main Methods:

• Experimental investigation of eutectic gallium-indium (EGaIn) oxide layer peeling.
• Theoretical analysis of delamination mechanics at varying contact angles.
• Nanoscale examination of the oxide-air interface during delamination.

Main Results:

• Clean peeling of the EGaIn oxide layer is achieved by maintaining a large contact angle during slow delamination.
• Failure to peel cleanly at small contact angles is attributed to mechanical fracture of the oxide skin.
• The study identifies the nanoscale failure mechanism at the oxide-air interface.

Conclusions:

• A novel, gentle delamination strategy for GBLMs is established.
• Fundamental insights into the interfacial mechanics of GBLMs are provided.
• This work offers a framework for enhanced control in liquid metal applications.