Total-internal-reflection-fluorescence microscopy for the study of nanobubble dynamics

Area of Science:

• Physical Chemistry
• Nanotechnology
• Optical Microscopy

Background:

• Nanobubbles are nanoscale gas pockets in liquids.
• Observing nanobubbles requires high-resolution imaging techniques.
• Total-internal-reflection-fluorescence (TIRF) microscopy offers potential for nanobubble visualization.

Purpose of the Study:

• To visualize nanobubbles using TIRF microscopy.
• To investigate nanobubble nucleation dynamics.
• To quantify fluid flow near nanobubbles.

Main Methods:

• Utilized TIRF microscopy with rhodamine 6G (5 μM) for enhanced contrast.
• Observed nanobubbles with diameters of 230 nm and above.
• Analyzed nucleation dynamics during water-ethanol-water exchange.
• Tracked tracer particles near nanobubbles to assess fluid flow.

Main Results:

• Achieved strongly contrasting images of nanobubbles via TIRF.
• Detected nanobubbles as small as 230 nm in diameter.
• Observed nanobubble nucleation and stable population formation within 4 minutes.
• Quantified minimal drift flow (< few μm/s) at 400 nm from nanobubble centers.

Conclusions:

• TIRF microscopy with rhodamine 6G is effective for nanobubble detection and characterization.
• Nanobubble nucleation is a rapid process following specific environmental changes.
• Fluid flow in the immediate vicinity of nanobubbles is negligible, supporting their stability.