Design, Realization and Optimization of an Acoustic Levitator addressed to Condensed Matter Studies

This paper deals with an acoustic levitator, which has been engineering designed, optimized and then employed for performing chemical-physical analysis on levitated water mixtures of Ethylene Glycol. In particular, it is a single-axis levitator, which enables non-contact positioning and manipulation of solid and liquid samples of diameter between 0.5 and 3.5 mm versus time. Two acoustic transducers, an oscilloscope, an amplifier and a video camera forming the system that is optimized with a specific room for thermostatically regulating the temperature of the sample at a precise value and to protect the system from significant air currents, that can destabilize the levitated sample. The designed system allows to access deeply super-cooled and potentially supersaturated liquids in conditions that avoid heterogeneous nucleation by a container. Acoustic levitation can be also used for sample preparation of high concentrated mixtures starting from solutions. It can be used in many fields, especially for high added value products as it occurs, for example, in pharmaceutics. The experimental set-up can be also integrated by Infra-Red, Raman, Neutron or X-ray spectroscopy instruments. A significant example of system operation is also reported: levitated water mixtures of Ethylene Glycol sample, analyzed by an Infra-Red spectrometer. The study shows how this designed and optimized sample holder allows to follow the drying process versus time and to obtain a gel-like compound characterized by an extended chemical crosslinking. The obtained experimental findings together with their analysis allow to extract also information on the concentration values of the levitated systems.