Figure 4.

Representative examples of four categories of ultrasonic flow reactors. (a) Picture of a piezoelectric plate reactor developed by Dong et al., the reactor consists of a piezoelectric plate glued to the bottom of a silicon plate microreactor, reprinted with permission from [93], copyright Elsevier. (b) Capillary microreactor immersed in an ultrasonic bath, reprinted with permission from [97], copyright Elsevier. (c) Sketch of a Langevin-type transducer indirectly coupled reactor, reprinted with permission from [98], copyright Elsevier. (d) Sketch of a Langevin-type transducer directly coupled reactor, reprinted with permission from [34] copyright Royal Society of Chemistry.