Pulsating bubble technique for evaluating pulmonary surfactant

Area of Science:

• Physical Chemistry
• Materials Science

Background:

• Surface tension is a critical property influencing fluid behavior and interfacial phenomena.
• Accurate measurement of surface tension is essential for various scientific and industrial applications.

Purpose of the Study:

• To develop and validate a new apparatus for precise surface tension determination.
• To utilize bubble pressure analysis and the law of Laplace for accurate calculations.

Main Methods:

• A novel apparatus was designed, featuring a 20-microliter sample chamber connected to a pulsator and pressure transducer.
• Hydraulically geared pulsator (1:1000) with a 0.43-microliter stroke volume controlled bubble radius changes (0.55 mm to 0.4 mm).
• Bubble radius was accurately measured via microscopy, and pressure gradients were recorded.

Main Results:

• The apparatus successfully generated and measured pressure changes across a bubble within a 20-microliter sample.
• Calculations using the law of Laplace, based on measured pressure and radius, yielded surface tension values.
• The pulsator speed was adjustable (0.02 to 80 rpm), allowing for controlled bubble dynamics.

Conclusions:

• The developed apparatus provides a reliable method for determining surface tension.
• This technique offers high precision for surface tension measurements in small liquid volumes.
• The study validates the application of the law of Laplace in conjunction with bubble dynamics for surface tension analysis.