Design and Development of an Automated Surface Tension Analyzer Based on Bubble Pressure Variations

Abstract

A low-cost, automated surface tension analyzer was designed and developed based on the maximum bubble pressure method. The system measures the pressure required to form air bubbles through a capillary immersed in a liquid, allowing the surface tension to be determined from the pressure–depth relationship. The experimental setup integrates a pressure sensor solenoid valve, stepper-motor-controlled depth stage, and data acquisition unit. A Python-based software interface was developed for real-time signal processing. Validation was performed using several Newtonian liquids, including water, toluene, methanol, ethanol, and n-hexane, with experimental results showing strong agreement with theoretical values yielding a maximum deviation below 2%. The developed instrument demonstrates excellent repeatability and sensitivity confirming its suitability for research and industrial applications.