Sustained Synthesis of Ultra-Long Gold Wires via an Open Microfluidic System

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Metal nano/microwires are crucial for electronics, sensing, and catalysis.
• Microfluidic synthesis offers efficient production but faces challenges with wire widening due to diffusion.
• Achieving ultra-long, size-controlled metal wires remains a significant hurdle.

Purpose of the Study:

• To present an open microfluidic system for synthesizing ultra-long metal wires with controlled dimensions.
• To address the issue of diffusion-induced widening in microchannel-based wire synthesis.
• To demonstrate the feasibility of producing size-controllable, ultra-long metal wires.

Main Methods:

• Utilized an open microfluidic system with coflowing laminar streams for controlled mixing and reaction.
• Implemented aspiration to truncate laminar streams, restricting diffusion and preventing wire widening.
• Investigated synthesis conditions specifically for gold nanowires.

Main Results:

• Successfully synthesized gold nanowires with a controlled width of 370 nm.
• Obtained two ultra-long gold wires, each exceeding 3600 μm in length.
• Demonstrated direct assembly of a gold wire on patterned indium tin oxide (ITO) chips for resistance monitoring.

Conclusions:

• The developed open microfluidic system effectively synthesizes ultra-long metal wires with size controllability.
• The truncation method successfully mitigates diffusion-induced widening, enabling longer wire formation.
• The system shows promise for fabricating tailored metal wires for electronic applications.