Systematic Review of the Theories and Applications of Acoustic Levitation of Liquids

The purpose of the levitation process is to neutralize the gravitational force on the sample with the help of a non-contact force and levitate the sample in the air without contacting the secondary surfaces. The benefits of eliminating the contact of a substance with external surfaces have led to the attention of the levitation process. Considering that among the levitation methods, ultrasonic levitation is the only method that can be applied to materials with different physical properties and geometries, levitation of the material in the liquid phase can also be done with the help of this method. The potential of ultrasonic levitation of liquids for use in cases such as pharmaceuticals, biology, controlling the structure of matter, etc., has led to several types of research in the field of improving the conditions of this process. In this article, an attempt has been made in the first part to review the theory and analytical relationships of the ultrasonic levitation process, and then in the second part, the studies conducted in the field of improving the conditions of the levitation process and the factors affecting it have been examined. Finally, the future of research in this field has been looked at.