# Advances in Piezoelectric Jet and Atomization Devices
## 3 Advances in Piezoelectric Atomizers
### Static Mesh Atomizer  
In 2000, [PERSON] et al. [42] proposed a static microporous atomizer, as shown in Figure 2a. The atomizer was composed of a piezoelectric ceramic (PZT), a liquid inlet, and a metallic plate with micro apertures. These holes were obtained by deep reactive ion etching. The properties of the atomizer were tested using a high-speed camera and a Doppler laser vibrometer. In 2001, [PERSON] et al. [43] designed an atomizer with a structure similar to that shown in Figure 2a. The atomizer exhibited a stable working performance and atomization rate. Subsequently, [PERSON] et al. [44] and [PERSON] et al. [45] provided a further study on this type of atomizer. In 2006, [PERSON] [46] took advantage of electroplating technology to prepare 6000 small holes with a diameter of 3 \(\upmu\)m on the mesh plate, and atomized the drug solution into aerosol through the high-frequency vibration of the high-frequency transducer. Finally, the drug directly reached to the lesion through the human respiratory system, and thus the targeted and quantitative administration could be realized to reduce the side effects of systemic administration (as shown in Figure 2b). As shown in Figure 2c, a new type of static mesh atomization device was proposed to achieve high-quality atomization, and the particle size of the generated droplets was finer and more uniform than that of industrial aerosolization [47]. Simultaneously, [PERSON] et al. [48; 49] proposed a dual-piezo-driven high-frequency resonance atomizer, the working principle of which is shown in Figure 2d. The experimental results showed that the atomization rate could be enhanced to a value of 8 mL/min at a driving frequency of 7 kHz. Table 2 shows the summary of properties for the static mesh atomizer. \begin{table}
\begin{tabular}{c c c c c} \hline
**Type** & **Working Principle** & **Advantage/Disadvantage** & **Application** \\ \hline Static mesh atomizer & The vibration of the piezoelectric vibrator is adopted to change the pressure inside the liquid cavity. When the pressure in the cavity is sufficiently large, the liquid is ejected from the micro-jetting hole, resulting in atomization. Under the vibration of the piezoelectric vibrator, the droplet is broken and refined repeatedly by adjusting the balance of inertia force and capillary force, to thereby obtain atomization. & Atomization process is controllable, and the structure energy utilization. & Spray cooling, inkjet printing, inhalation therapy. \\ \hline Dynamic mesh atomizer & & & \\ \hline \end{tabular}
\end{table} 
Table 1: Working principle, characteristics, and application of different types of piezoelectric atomizers. \begin{table}
\begin{tabular}{c c c c c c} \hline
**First Author** & **Working Frequency** & **Working Voltage** & **Atomization Rate** & **Particle Size** & **Atomization** \\
**and Year** & **(kHz)** & **(V)** & **(mL/min)** & **(W)** & **Medium** \\ \hline
2000 [42] Heij & 250.0 & N/A & 1.2 & 4.7 & Water \\
2001 [43] [PERSON] & 200.0 & N/A & 0.6 & 5.0 & Water \\
2002 [44] [PERSON] & 36.0 & 80.0 & N/A & 9.94 & Deionized water \\
2004 [45] [PERSON] & 0.4–1.0 & N/A & N/A & N/A & Water \\
2006 [46] [PERSON] & 180.0 & 220.0 & 7.0 & N/A & Water \\
2007 [47] [PERSON] & 16.0 & N/A & 1.8 & 6.13 & Water \\
2007 [48] [PERSON] & 18.0 & 20.0 & 1.6 & N/A & Water \\ \hline \end{tabular}
\end{table} 
Table 2: Summary of properties for the static mesh atomizer. All the static mesh atomization devices mentioned above are composed of a liquid cavity, piezoelectric vibrator, and micro spray hole. The working principle of this kind of atomizer is to use the vibration of the piezoelectric vibrator to change the pressure inside the liquid cavity to realize atomization. The atomization process can be effectively controlled, and the device has the advantages of being easy to carry, with a low manufacturing cost and easy to realize miniaturization. However, the energy of this type of device is applied to the whole liquid system, resulting in low energy utilization efficiency.