Photothermal generation of programmable microbubble array on nanoporous gold disks

Area of Science:

• Microfluidics
• Nanotechnology
• Laser Physics

Background:

• Microbubble generation is crucial for various microfluidic applications.
• Existing methods often have limitations in control, lifetime, or require additives.

Purpose of the Study:

• To develop a novel, dye-free technique for controlled microbubble generation in microfluidic channels.
• To investigate the dynamics of microbubble formation, growth, and shrinkage.
• To demonstrate the capability for simultaneous, independently controlled multi-bubble generation.

Main Methods:

• Utilizing continuous-wave laser irradiation on nanoporous gold disk (NPGD) arrays within microfluidic channels.
• Employing computer-generated holography with a spatial light modulator (SLM) for precise laser focusing.
• Analyzing microbubble dynamics through controlled laser power adjustments.

Main Results:

• Successful photothermal generation of single microbubbles with controllable size via laser power.
• Demonstration of simultaneous, arbitrary, and independently controlled generation of multiple microbubbles.
• Observation of long microbubble lifetimes and controlled shrinkage.

Conclusions:

• The NPGD-based photothermal technique provides a highly controllable and flexible method for microbubble generation.
• This approach enables precise flow manipulation in microfluidic devices without light-adsorbing dyes.
• The technique offers advantages in controllability, bubble lifetime, and power efficiency.