# Innovative Ultrasonic Spray Methods for Indoor Disinfection
## 5 Conclusions  
The results of this study highlight the potential of ultrasonic atomization as a transformative approach to the disinfection of individuals, surfaces, vehicles, and large spaces. Traditional spraying methods, such as hydraulic and pneumatic systems, exhibit significant limitations, including inefficient droplet size control, uneven surface coverage, and incompatibility with disinfectants of varying viscosities or those containing nanoparticles. These shortcomings contribute to excessive disinfectant usage, reduced efficacy, and potential health risks from aerosol inhalation. In contrast, ultrasonic atomization offers precise control over droplet size, nearly monodisperse droplet distributions, and compatibility with diverse liquid compositions. By leveraging ultrasonic vibrations, this technique ensures a uniform nanoparticle dispersion within droplets, minimizes waste, and enhances safety. Additionally, innovative acoustodynamic methods, such as multi-stage atomization and cavitation-assisted spraying, further optimize droplet dispersion and increase productivity, addressing the constraints of conventional ultrasonic systems. This work makes several key contributions. It advances droplet generation technology by enabling ultrasonic atomizers to precisely control droplet sizes, allowing customization for various disinfection needs, ranging from personal hygiene to large-scale applications. The developed systems also enhance compatibility, efficiently atomizing high-viscosity liquids and two-phase disinfectant solutions, including those with silver nanoparticles, while ensuring uniform application without agglomeration. Additionally, innovative atomizer designs were introduced, featuring enhanced performance, controlled droplet size, and improved efficiency. Finally, the approach offers significant environmental and health benefits by reducing aerosol exposure risks and optimizing disinfectant use, leading to safer and more sustainable disinfection practices. The proposed ultrasonic spraying systems have the potential to significantly improve global disinfection efforts, particularly in the face of emerging infectious diseases. By  
Figure 17: Histograms of particle size distribution in the combined cavitation spraying method: (**a**) at a pressure of 6 atm (amplitude 33 \(\upmu\)m); and (**b**) at a pressure of 11 atm (amplitude 47 \(\upmu\)m). overcoming the limitations of traditional methods, these technologies enhance the effectiveness and efficiency of disinfection in public health and industrial contexts. Applications extend to hospitals, public transportation, schools, and urban spaces, reducing pathogen transmission and improving environmental sustainability. Future research should aim to enhance aerosol production rates by developing hybrid designs that combine ultrasonic and hydraulic mechanisms. It should also explore novel materials and geometries to improve the energy efficiency and overall performance of these systems. Another important direction is the creation of automated, adaptive systems that can adjust in real time to varying liquid properties and disinfection conditions. Addressing these challenges will enable ultrasonic spraying technologies to become a cornerstone of modern disinfection strategies, contributing to public health protection and supporting sustainable hygiene practices globally. Conceptualization, A.S., V.K. and O.K. ; methodology, A.S. and V.K. ; software, S.T. and V.N. ; validation, A.S. and O.K. ; formal analysis, O.K. ; investigation, D.G. ; resources, A.S.; data curation, V.N and D.G. ; writing--original draft preparation, A.S. and O.K. ; writing--review and editing, A.S., S.T. and O.K. ; visualization, V.N. and S.T. ; supervision, V.K. ; project administration, A.S.; funding acquisition, A.S. All authors have read and agreed to the published version of the manuscript.