Dielectric analysis of polystyrene microcapsules using scanning dielectric microscope

A dielectric imaging technique with a scanning dielectric microscope was applied to polystyrene microcapsules in an aqueous environment to study the electrical properties of individual ones. The dielectric images obtained over a frequency range from 10 kHz to 10 MHz showed frequency dependence, which indicated dielectric dispersion (or relaxation) due to interfacial polarization or the build between the microcapsule shell and the aqueous phases. The dielectric dispersion was analyzed based on an equivalent electrical circuit model and a shell-sphere model in which a spherical core is covered with an insulating shell.