Enhancing optofluidic actuation of micro-objects by tagging with plasmonic nanoparticles

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Optical forces are crucial for manipulating microparticles.
• Metallic nanostructures can enhance light-matter interactions via surface plasmon resonance.

Purpose of the Study:

• To investigate the effect of metallic nanodot coatings on optical forces acting on microparticles.
• To quantify the enhancement of optical forces due to metal concentration on microparticle surfaces.
• To explore the potential of these enhanced microparticles for advanced applications.

Main Methods:

• Experimental characterization using an optical chromatography setup to measure Stokes drag.
• Theoretical modeling comparing Mie theory predictions with experimental results.
• Analysis of pure silica and silica-gold composite microparticles.

Main Results:

• Metallic nanodot coatings significantly exalt optical forces on microparticles under laser illumination.
• Observed forces quantitatively agree with theoretical predictions based on metal concentration.
• Even low concentrations of metallic nanodots markedly increase optical forces compared to pure dielectric particles.

Conclusions:

• Metallic nanodot-coated microparticles exhibit enhanced optofluidic manipulation capabilities.
• These particles effectively act as 'micro-sized nanoparticles', bridging microscale manipulation with nanoscale functionalities.
• The findings open avenues for advanced microscale optical, chemical, and biological applications.