The Research Of Variable-focus Ultrasonic Liquid Lens Based On The Electro-wetting Effect

Ultrasonic technology develops rapidly in many fields since its birth,such as daily life,engineering measurement and detection, medical diagnosis and treatment,scientific research and analysis.It is also an important research direction in biomedical engineering, of which the key technology is focusing,and it has made important contributions to medical research and clinical medicine.Ultrasonic focusing technology has been paid more and more attention by researchers at home and abroad,and a lot of scientific research work has been carried out.There are two kinds of existing methods of focusing, 1) Ultrasonic energy focus by a piezoelectric ceramic transducer or ultrasonic lens with a certain geometry(concave spherical surface) or through a solid lens, whose structure is simple but the focal length is fixed, so the only way to change the focal position is to adjust the place of the transducer using a mechanical method; 2) Ultrasonic energy focus based on the principle of phased array, which is to control the different initial states of each source unit to focus acoustic beam at the focal point. Its principle and structure is complex,so it is expensive and difficult to apply in the high-power ultrasonic focusing.Ultrasonic liquid lens has been proved that it can focus ultrasonic energy through some researches. So we improved a kind of variable-focus liquid lens based on the existing liquid lens, which can change its focal length quickly and accurately through the external control voltage based on the electro-wetting effect.In this paper, theoretical principle of ultrasonic liquid lens was researched, and a kind of variable-focus liquid lens model using in the ultrasonic field was demonstrated.1) The possibility of the liquid lens using in the ultrasonic field was researched,and the relationship between control voltage and the distribution of the ultrasonic field was obtained through simulation.2) Impact trend of the related parameters, including external voltage, viscosity of the liquid material, and the thickness of the hydrophobic coating was got through simulation, which can provide reference of the actual production of the lens.There are some advantages of the liquid lens model proposed in this paper:1) It’s low cost because the structure of the model is simple. The control way with the external voltage is simple, quick and accurate.2) There are many choices for the liquid material and container type of the liquid lens according to the practical applications, so a lot of different liquid lens based on this principle can be designed.There is something we will explore in our next work with more experiments, like the influences of the aperture, liquid materials and density, and the production process level etc.