## 1 Introduction  
The past century has been characterized by rapid advances in materials development, especially in functional materials, such as piezoceramic materials. Nowadays, on one hand, piezoceramic materials have found a wide spectrum of commercial applications [1; 2], such as ultrasonic measurement [3; 4; 5], vibration sensing and control [6; 7; 8], force sensing [9; 10], pumping and dosing [11; 12; 13], ultrasonic cleaner, ultrasonic welding, energy harvesting [14; 15] and imaging [16], among others. On the other hand, piezoceramic materials and devices are still being actively researched to achieve better performance with lower cost and less environmental impact [17; 18; 19].  
One of the actively researched piezoceramic devices is the atomizer, which utilizes a piezoceramic actuator to convert liquid to atomized particles through high frequency ultrasonic vibration; it can cause ultrafine droplet atomization. Ultrafine droplet atomization is widely applied in combustion with liquid fuel [20], inhalation therapy [21; 22; 23], printed circuits [24], three-dimensional (3D) prototyping [25], precise surface coating [26; 27], spray drying [28], spray cooling [29; 30], and inkjet printing [31],among other fields. Ultrafine droplet atomization has high important application potential, and scholars began to focus on atomization devices.  
[PERSON] first provided a detailed explanation of the actuating principle of a surface acoustic wave atomizer [32]. [PERSON] et al. designed an extrusion-type piezoceramic ultrasonic atomizer that produced droplets with an average diameter of 27 \(\upmu\)m [33]. The working mechanism of this type of atomizer is to release energy to the entire liquid system to break the surface tension of the liquid and allow the droplets to escape from the surface for atomization and ejection. The atomization is formed at the surface of the liquid. However, the energy is applied to the entire liquid system.  
[PERSON] et al. proposed a stationary vibrating mesh atomizer driven by piezoelectricity to improve energy use, minimize the droplet size range and strengthen control over the atomization process [34]. To further minimize the droplet size range, [PERSON] et al. designed a new type of stationary micro-cone hole driven by piezoelectricity [35]. In this type of atomizer, the pressure inside the liquid chamber is modulated by the vibration of a piezoelectric vibrator, and the liquid is ejected from the micro-jet hole when the pressure inside the liquid chamber is sufficiently large, resulting in atomization. In designing this type of atomizer, it is necessary to add an atomizer chamber with variable volume. The structure of this type of atomizer is complex, which limits the miniaturization of the atomizer.  
In this research, the micro-cone hole is machined within the plate metals of the vibrating mesh atomizer. There is no liquid chamber with variable volume in the process of atomization, the structure of the atomizer is simplified, and the atomization process can be controlled. [PERSON] et al. proposed the atomizer with this structure [36; 37]. [PERSON] et al. designed an efficient cooling device that used a vibrating mesh atomizer [38; 39]. This type of atomizer can effectively improve energy use and minimize the droplet size range. It also has the advantages of portability and straightforward integration, resulting in a revolutionary influence on combustion with liquid fuel [40; 41].  
We previously determined that the micro-cone hole of the vibrating micro-porous atomizer has an important influence on the atomization effect, particularly the dynamic change of the cone angle of the atomizer under the working conditions. Therefore, this study was designed to verify the dynamic change of the micro-cone angle and its effect on the atomization effect of the vibrating mesh atomizer.