Understanding and controlling plasmon-induced convection

Area of Science:

• Optofluidics
• Plasmonics
• Nanotechnology
• Heat Transfer

Background:

• Plasmonic nanostructures induce heat and fluid convection, crucial for optofluidic applications.
• Previous studies predicted low fluid velocities (nm/s), insufficient for microscale mass transport.

Purpose of the Study:

• To demonstrate theoretically and experimentally high fluid convection velocities (> µm/s) using plasmonic nanoantennas on an ITO substrate.
• To investigate the role of ITO in enhancing convection and altering optical absorption.

Main Methods:

• Fabrication of plasmonic nanoantenna arrays.
• Coupling nanoantennas to an optically absorptive indium-tin-oxide (ITO) substrate.
• Theoretical modeling and experimental validation of fluid convection.
• Analysis of optical absorption properties of the ITO substrate.

Main Results:

• Achieved fluid convection velocities exceeding micrometres per second.
• ITO substrate significantly enhanced convection (order of magnitude) compared to SiO2.
• Observed altered absorption in ITO due to plasmonic array, deviating from Beer-Lambert law.
• Identified an optimal ITO thickness for maximizing convection.

Conclusions:

• Plasmonic nanoantennas on ITO substrates enable efficient microscale fluid and mass transport.
• The findings elucidate convection's role in plasmonic optical trapping and particle assembly.
• Opens new possibilities for controlling transport phenomena at the micro- and nanoscale.