Types of ultrasonic devices

Ultrasounds can be applied to chemical systems by using ultrasonic baths or probes. Although baths are more widely used, probes are more efficient as a result of (a) the lack of uniformity in the transmission of ultrasounds (in baths, only a small fraction of the total liquid volume in the immediate vicinity of the ultrasound source experiences the effects of cavitation) and (b) the decline in power with time, which leads to exhaustion of the energy applied to baths. Both phenomena result in substantially decreased experimental repeatability and reproducibility. For this reason, the use of baths should be restricted to cleaning operations and removal of dissolved gases, their intended applications. A wide variety of commercially available ultrasonic baths exists ranging from laboratory to industrial-scale models. 

By contrast, ultrasonic probes (also called sonotrodes ) focus their energy on a specific sample zone, cavitation in which is thus enormously boosted. Also, they are subject to no exhaustion restrictions, so they are much more suitable for use in analytical chemistry than are ultrasonic baths. 

One other question to be taken into account with ultrasonic probes is that they are more flexible as regards construction, which allows them to be designed for specific purposes. What effects ultrasounds have on a process depends on a number of factors including the direction, amplitude and frequency of the vibrations at the point of application, and the method of clamping the workpiece. All of these should be specified with 

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Two different types of ultrasonic devices are used in laboratories ultrasonic bath and ultrasonic probe. However, as a result of inhomogeneity of ultrasonic energy distribution in the whole solution and a decrease in power with time, the repeatability and reproducibility of experimental conditions for ultrasonic baths is often unsatisfactory. With ultrasonic probes the energy is focused on a small sample area, which significantly improves cavitation efficiency and, thereby, extraction effectiveness [56]. 

Type of Ultrasonic Device Hill and Harris (2007) have discussed the merits and drawbacks of various materials that can be used for generating the acoustic effect. Lead zirconate titanate type is the most widely used and effective piezo material. 

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