# An Overview on Atomization and Its Drug Delivery and Biomedical Applications
## 9 Conclusions  
The study on atomization started decades ago and this has helped us to understand the complexity of the process and to exploit it in different fields. By sharply studying the topic, it is understood that atomization is simply the process of breaking down the working fluid into fine droplets. However, in order to break down the liquid into droplets, there are certain factors that come into the play of atomization. Pressure is one main factor that plays a major role in atomization. When the liquid is pressurized to flow through a small orifice, the surface tension of the liquid causes it to come out of the opening either as a jet or a sheet which then comes in contact with the surrounding air to disrupt into small droplets. This disruption of the jet or sheet is studied as primary atomization and secondary atomization. The stagnant drop formation is explained by quasi-steady state equilibrium and the modelling proposals are extracted from linear stability review. The kinetics of the liquid jet and sheet explains the instability and the process of disruption of jet or sheet into droplets. The direct development of disequilibrium on both liquid jet and sheet has been explained using simple mathematical formulations after surveying the literature. In the initial literature studies the viscosity of the fluids were not considered but later on the properties of the fluids including the viscosity of both the fluids, i.e., both working fluid and surrounding air is considered to calculate the size of the generated droplets. This has helped the researchers in understanding the fluid dynamics of liquid jet or sheet in the process of atomization by considering the impact of momentum contour, dimensionless quantities and the kind of disequilibrium magnification. It is also reported in literature that the disequilibrium distortion of the liquid jet and sheet into fine droplets is directly influenced by the momentum profiles and the thickness of the liquid jet or sheet. It is studied that the size of the droplets generated from atomization depends on various factors including the liquid properties and the experimental parameters. The liquid properties include the viscosity and surface tension of the working liquid and the experimental parameters include the pressure, temperature, the type of the atomizers and the energy source. Another factor which plays an important role in droplet diameter determination and its size distribution is the ratio of the mass flow rate of gas to liquid (GLR). It can be postulated from the literature that as the GLR value is increased the energy to the droplet from the nozzle is higher which can overcome the viscous force and thereby providing an upgraded atomization feature. Even if there is a correlation between the experimental and theoretical models, further investigation will be required to understand various effects that have been expressed in the experimental data like the dip of the speed of the droplets during the downstream process of atomization which is not considered in the theoretical model. Even though there are different types of atomization process depending on the energy source, electrohydrodynamic atomization is considered the most versatile as it generates spherical, small, uniform and homogeneous particles compared to other types. Due to its versatility, the electrohydrodynamic or electrospray atomization is widely used in different fields like food processing, drug delivery, cell encapsulation, sensing, diagnostic and therapeutic imaging, implant coating, tissue engineering and vaccine delivery. The main advantage of electrospray is that it generates fine particles with confined size and shape and can be used for various biomedical applications. Compared to other complex techniques, this is a simple, robust and one-step process. To improve the efficiency of the technique, scientists have modified the procedure for example with needeless equipment, numerous dispersing jets, etc.