Laser scattering from the Ag nanofluids droplet on a plate and the surface tension measurement by scattering technique

We developed a new optical method to detect the variation of the surface tension in this work. The distribution of laser scattering from Ag nanofluids droplet on the inclined plate was collected experimentally, and the Airy structures were found in the scattering distribution. The relationship between the scattering field distribution and the liquid surface tension was derived theoretically, and the dependence of the Airy peak of the laser scattering on the surface tension was provided. Based on the relationship between the scattering field distribution and the surface tension, an optical method for the relative measurement of surface tension is established. The surface tensions of Ag nanofluids at different concentrations were measured by this optical means, and it is easy to detect the variation of Airy peak gap vs the Ag particle concentration. The results show that the surface tension of Ag nanofluids decreases with the particle concentration increase when the concentration is less than 3.16 wt. %. This work provides a new idea for surface tension measurement of nanofluids, and it has applications in the field of nanofluids wetting.