Additive Manufacturing of Gold Nanostructures Using Nonlinear Photoreduction under Controlled Ionic Diffusion

Area of Science:

• Materials Science
• Nanotechnology
• Laser-based Fabrication

Background:

• Direct laser writing (DLW) offers sub-micron scale synthesis of metallic structures.
• Multiphoton photoreduction is a key mechanism in laser-based material processing.
• Controlling nanoparticle size and density is crucial for advanced material properties.

Purpose of the Study:

• To investigate and optimize direct laser writing (DLW) for synthesizing gold nanostructures (AuNSs).
• To achieve precise control over the size and density of AuNSs using tunable fabrication parameters.
• To explore the role of post-processing steps in refining AuNS characteristics.

Main Methods:

• Utilized femtosecond NIR laser (780 nm) for two-photon absorption triggered DLW.
• Employed tetrachloroauric acid (HAuCl4) as a gold precursor within a natural hydrogel matrix (isinglass).
• Investigated effects of laser power, exposure time, scanning speed, and a secondary Au3+ bath on AuNS formation.

Main Results:

• Optimized DLW parameters enabled control over pattern formation and AuNS size.
• Post-writing processing, including a deionized water bath, effectively removed precursor ions and the matrix.
• A secondary bath with Au3+ further influenced AuNS size and density, revealing individual gold nanoparticle (AuNP) growth.

Conclusions:

• DLW is a viable technique for fabricating controlled gold nanostructures.
• Fine-tuning of writing and post-processing parameters allows for high-quality structures with controlled AuNS size and density.
• This method provides a pathway for precise nanoscale metallic material synthesis.