On the formation of monodisperse charged nanoparticles and its applications

Experimental studies on a novel method of producing nearly monodisperse charged nanoparticles are presented in this paper. Ultrasonic piezoelectric actuators in MHz range are used to excite standing capillary waves in a thin liquid film on a diaphragm. The capillary waves with wavelengths on the order of microns are set to reach a critical stable condition and an electric field is applied to extract charged nanoparticles from the unstable wave crests. Experimental studies with room temperature salt water have shown that this method is more efficient than the method based on stable Taylor cones working in the cone-jet mode in producing large quantity of monodisperse nanoparticles. Average particle size is calculated based on the experimental measurements of the total current carried by the electrospray over a given surface area. Applications in the area of electric propulsion and nano coating are also discussed.