Electric field tweezers for characterization of liquid surface

The authors have developed a novel technique to measure the surface properties of soft condensed matters in a noncontact manner. In this method, the Maxwell stress applied by a needle electrode deforms the surface. The magnitude of the displacement is determined by the surface tension as the restoring force, while its dynamic response is determined by the sample viscosity. The surface tension was measured for the aqueous solutions of the surfactant sodium dodecyl sulfate at various concentrations and the result shows good agreement with the conventional method. Further, the viscosity measurement was also carried out in the range of 0.1–103Pas.