Optical Surface Tension Measurement Method for Microscale Liquid

Quasi-elastic laser scattering (QELS) method is an optical scattering measurement technique by thermally excited capillary wave at gas / liquid and liquid / liquid interfaces. It can measure surface tension optically, which is a distinctive feature in micro-nano sciences. While conventional QELS method requires precise scattering-angle determination and light's wavelength information for surface tension calculation, new QELS method utilizes spontaneous capillary wave resonance at spatially restricted interfaces in microchannels, microwells, and microdroplets, where the modes' characteristics and their sizes are required for the tension. This paper provides an explanation of the principle of the method, demonstrats the measurements for gas / liquid interfaces in the microchannels, microwells, and microdroplets, and discusses the method's usefulness for contemporary micro-nano sciences.

Automated summary

The quasi-elastic laser scattering (QELS) method is an optical scattering measurement technique that utilizes thermally excited capillary waves at gas/liquid and liquid/liquid interfaces. It can optically measure surface tension, which is a distinct characteristic in micro-nano sciences. Unlike conventional QELS methods, the new QELS method utilizes spontaneous capillary wave resonance at spatially restricted interfaces in microchannels, microwells, and microdroplets, eliminating the need for precise scattering angle determination and wavelength information for surface tension calculation.