# Advances in Piezoelectric Jet and Atomization Devices
## 3 Advances in Piezoelectric Atomizers
### Dynamic Mesh Atomizer  
In 1986, [PERSON] et al. [50; 51] proposed a new atomizer structure with a piezoelectric vibrator. It was composed of the piezoelectric element, liquid chamber, pinhole, pinhole  
Figure 2: Static mesh atomizer: (**a**) a SMA by [PERSON] et al. [42], reprinted with permission from Ref. [42]. Copyright 2000 Elsevier, (**b**) an innovative SMA adapted from [PERSON] et al. [47], (**c**) a SMA adapted from [PERSON] [46], and (**d**) a new structure SMA by [PERSON] et al. [48; 49], reprinted with permission from Ref [48; 49]. Copyright 2007 Elsevier. plate, water tank, and pipe. In the course of the work, one side of the atomizer was in direct contact with liquid, whereas the other side was in contact with air. The variable volume of the liquid cavity simplified the structure of the atomizer, and thereby the atomization process could be controlled effectively. In 1994, [PERSON] et al. [52] proposed a type of piezoelectric atomizer containing micro holes. Each micro hole on the atomizing plate was a tapered hole driven by the vibration of a piezoelectric vibrator. Under the action of the vibration plate, the liquid atomized as it flowed through the plate. [PERSON] et al. [53; 54] also conducted the related experiments, and the corresponding results showed that the atomization rate reached 0.6 mL/min when the driving voltage was 70 V. In 1997, [PERSON] et al. [55; 56; 57] designed a piezoelectric atomizer as shown in Figure 3a. The shaft excited on a circular film by a flexural transducer and was stacked into a resonant film to generate atomization [58; 59]. In 2008, [PERSON] et al. [60] studied an atomizer with a cymbal-type high-power drive as shown in Figure 3b. This atomizer was composed of a piezoelectric disk, aperture, cylindrical housing, and thin shim. For the cymbal-type nozzle, the energy could be accumulated at the center of the nozzle plate, and a large driving force was generated to provide a high-power driver of the cymbal shape, atomizing the high-viscosity liquid into fine particles, and increasing the atomization rate. In 2016, [PERSON] et al. [61] designed an atomization device as shown in Figure 3c and investigated the effects of the dynamic cone angle pump on the atomization performance. [PERSON] et al. [62] explained the mechanism of the dynamic mesh atomizer as follows: the liquid is pinched off as droplets pass through the cone nozzle during forward vibration and then adheres to the orifice by capillary force during backward vibration. At this point, the micro-cone hole is in the nozzle mode, and the liquid flows from the flared (the larger diameter of the micro-cone hole) side to the tapered side (the smaller diameter of the micro-cone hole). However, [PERSON] et al. [61] proved that the viewpoints from [PERSON] et al. [62] were not correct in explaining the atomization mechanism (as shown in Figure 3c). In 2018, [PERSON] et al. [63; 64; 65] conducted an in-depth study on the mechanism of the micro pump with a dynamic cone angle, as shown in Figure 3d. Simultaneously, [PERSON] et al. explored the effects of the dynamic cone angle on the atomization process. Table 3 shows the summary of properties for the dynamic mesh atomizer. Figure 3: Dynamic mesh atomizer: (**a**) a DMA adapted from [PERSON] et al. [55; 56; 57], (**b**) a new structure DMA by [PERSON] et al. [60], reprinted with permission from Ref. [60]. Copyright 2010 Elsevier, (**c**) a DMA adapted from [PERSON] et al. [61], and (**d**) a diagram of the atomization mechanism adapted from [PERSON] et al. [63; 64; 65]. At present, the dynamic mesh atomizer has been widely used in household medical atomizers for children. Many companies have produced this type of medical atomizer. Famous brands of medical atomizers are as follows: Oranger, Pari, and Andon. Compared with the static mesh atomization device mentioned above, it seems that the dynamic mesh atomizer is relatively simple in construction, and the energy is directly applied to the liquid at the cone hole, which greatly improves the energy utilization rate.