Activation-Free Liquid-Metal Composite Elastomers via Ultrasonic-Enabled Interface Welding for Strain-Insensitive...

Area of Science:

• Materials Science
• Nanotechnology
• Electronics Engineering

Background:

• Liquid metal (LM)-based stretchable electronics face challenges due to insulating oxide shells, requiring destructive post-activation or limiting extreme-strain performance.
• Conventional methods often result in blends with suboptimal mechanical and electrical properties under high strain.

Purpose of the Study:

• To develop an activation-free liquid metal composite elastomer (ALCE) with enhanced stretchability and conductivity.
• To overcome limitations of native oxide shells in liquid metal electronics.
• To create a scalable strategy for high-performance bioelectronics.

Main Methods:

• Utilized acoustic cavitation for in situ alloying between liquid metal nanoparticles and silver nanowires (Ag NWs), creating a robust metallurgical interface.
• Engineered a macroscopic gradient architecture through solvent evaporation, forming a continuous conductive bottom network protected by a polymer-rich upper layer.
• Characterized conductivity and strain insensitivity of the ALCE.

Main Results:

• Achieved a conductivity of 2.4 × 10⁶ S/m.
• Demonstrated exceptional strain insensitivity, with resistance change R/R₀ = 1.8 at 1200% strain, due to robust welded junctions and gradient architecture.
• Exhibited an initial decrease in resistance up to 400% strain, compensating for deformation-induced increases.

Conclusions:

• The activation-free liquid metal composite elastomer (ALCE) offers a scalable strategy for high-performance stretchable electronics.
• The material's robust interface and gradient architecture enable unprecedented strain insensitivity and conductivity.
• Demonstrated practical applications in robust stretchable sensors and skin-conformable interactive systems.