Simultaneous measurement of surface tension and viscosity of oscillating droplet using time-resolved rainbow refractometry

Oscillation of micron-sized liquid droplet is an interesting and common phenomenon, and is used to measure surface tension and viscosity with the recently developed time-resolved rainbow refractometry. Droplets produced by a monodisperse droplet generator are excited to oscillate at a small amplitude (less than 1%) and high frequency (of the order of 10 kHz) by applying a periodic tiny disturbance. The aspect ratio of a spheroidal droplet is quantified by time-resolved angular shift of rainbow signal. Thus the droplet shape oscillation is quantified by its unsphericity, instead of calculated from the polar radius or the variation of surface area. Experiments on several liquids were conducted to evaluate the validation of the experimental system. The results present that the relative errors of measured values of the surface tension and viscosity are less than 5% and 10%, respectively, promising the great potential of rainbow refractometry for liquid surface properties measurement. (c) 2021 Published by Elsevier B.V.

Automated summary

The oscillation of micron-sized liquid droplets can be measured using time-resolved rainbow refractometry to determine surface tension and viscosity. The method shows potential for improving experimental validation and reducing measurement errors, with relative errors of less than 5% for surface tension and 10% for viscosity.