Laser Controlled Manipulation of Microbubbles on a Surface with Silica-Coated Gold Nanoparticle Array

Area of Science:

• Microfluidics
• Nanotechnology
• Acoustics

Background:

• Microbubble generation and manipulation are crucial for microfluidic applications like mixing and propulsion.
• Current methods for microbubble control are limited to lateral movement or specific liquid properties, restricting practical use.

Purpose of the Study:

• To present a novel method for robust vertical manipulation of microbubbles.
• To overcome the limitations of existing microbubble control techniques.

Main Methods:

• Utilizing resonant laser focusing on hydrophilic silica-coated gold nanoparticle arrays in water to generate plasmonic microbubbles.
• Employing laser pulse control for adjustable bubble size and bouncing frequency, influenced by the three-phase contact line during surface wetting.
• Investigating the use of laser-induced thermal Marangoni flow to control rising bubble movement.

Main Results:

• Plasmonic microbubbles are generated and detach from substrates upon laser cessation.
• Adjustable bubble bouncing frequency and size are achieved through laser pulse control.
• Rising bubbles can be effectively pulled back using laser-induced thermal Marangoni flow, confirmed by PIV and simulations.

Conclusions:

• This study introduces a flexible method for vertical microbubble manipulation in microfluidics.
• The findings offer significant potential for applications in mixing, drug delivery, and soft actuators.