Reducing the diameter of the atomized particles by coating polymer membrane on the inner wall of micro-tapered holes of the ultrasonic mesh atomizers

Abstract

Atomized inhalation therapy with its rapid efficacy, low side effects and high medicine utilization, has become a crucial method for treating respiratory diseases. The depth of atomized particles deposition in the respiratory tract mainly depends on the particle diameter, making the reducing of the atomized particle size crucial for medicine deposit in lung. In the existing literatures, for the widely used dynamic mesh atomizer, the majority of the researches focused on the mechanical structure and the vibration characteristics of the atomizers. However, there is little researches on the micro-tapered holes of the metal sheet of the atomizer, despite the fact that the diameter of these tapered holes determines the size of the atomized particles. Due to the processing technology, the diameter of the micro-tapered holes cannot be further reduced, which greatly limits the development of the dynamic mesh atomizer in inhalation therapy. In this study, we consider the use of polymer coating on the inner wall of the micro-tapered holes to eliminate burrs, reduce the diameter of the holes, and ultimately reduce the size of the atomized particles. A theoretical model of the initial thickness of the coating polymer membrane and the rupture depth under the uniform air pressure applied to a single tapered hole was established. The metal sheets with different initial coating thicknesses were processed to verify the theoretical model by observing the quality of the inner surface and measuring the diameter of the holes. The particle size measurement experiment results show that when the initial coating thickness was 3 μm and 4.5 μm, the average particle sizes were reduced by 12.5 % and 23.2 %, respectively. Therefore, the proposed method can effectively reduce the atomized particles size, which helps to efficiently deposit atomized drugs in the lungs.