## 3 Setting of the Boundary Conditions
### The Boundary Setting in the Actual Support Mode
#### 3.2.2 Atomization Experiments of Different Boundary Conditions  
To further verify that the degree of freedom at the boundary of the atomizing sheet must be greater than or equal to 1, the atomization rate of the atomizing sheet under different resonant frequencies is measured under peripheral fixed support and peripheral simply supported. In this paper, the peripheral fixed support mode is simulated by using the epoxy adhesive to fix the atomizing sheet onto the clamping device. The peripheral simply supported mode is simulated by using the rubber ring and the atomizing sheet coated with waterproof glue to install it on the clamping device.  
The frequency sweep experiment of the atomizing sheet mounted on the clamping device is implemented by the precision impedance analyzer (LCR Meter 6630, MICROTEST, New Taipei City, Taiwan) to determine each resonant frequency. The frequency range is 10-200 kHz, and the experimental setup is shown in Figure 9.  
As shown in Figure 9, the resonant frequencies of the first several orders of the atomizing sheet are 22.5, 62, 110.5, and 160 kHz under peripheral  
Figure 8: Modes of support proposed by [PERSON] et al. [31]: (**a**) Peripheral simply supported (without waterproof sealant); (**b**) Peripheral simply supported (with waterproof sealant); and (**c**) Elastic support.  
Figure 9: Experimental system and measurement curves of the atomizer.  
peripheral fixed support, the first several resonant frequencies are 26.3, 62, 103.5, and 114.7 kHz. In this paper, to verify whether the atomizer can atomize when the degree of freedom is 0, the resonant frequencies obtained by the sweeping frequency in the peripheral fixed support mode are used for the atomization experiments. The setup of the atomization rate experiment system is shown in Figure 10.  
During the experiment, the driving frequency is swept from 10 kHz to 200 kHz, with an interval of 10 kHz, and the effective value of the driving voltage is set to be 80 V at different driving frequencies. The atomization rates of the atomizing sheet with peripheral fixed support and peripheral simply supported are shown as the red and black curves in Figure 11, respectively.  
Figure 11: Atomizing rate of the atomizing sheet under different driving frequencies and boundary conditions.  
Figure 10: Experiment setup of atomization rate measurement.  
As shown in Figure 11, by using the peripheral simply supported condition to fabricate the atomizing sheet, the atomization rate can achieve two peaks of 0.862 mL/min and 0.553 mL/min at 114.7 kHz and 160 kHz, respectively. However, the atomization rate is almost 0 at each driving frequency under the peripheral fixed support condition. Only at 140 kHz will the atomization rate be 0.04 mL/min, accounting for 4.6% of the peripheral simply supported.  
The experimental results show that the atomization rate under peripheral simply supported is consistent with the actual application. This finding further proves that the degree of freedom of the atomizing sheet boundary should not be 0. Therefore, the boundary conditions of the thin plate in the FE analysis of the atomizing sheet, set by [PERSON] et al., is inappropriate, which violates the actual support situation and leads to the corresponding unreasonable simulation results.