Design Of New Type Piezoelectrically Actuated Mesh Nebulizers

Inhalation drug therapy (IDT) is a prevailing method of respiratory tract therapy as a main non-invasive drug delivery. IDT can treat bronchus asthma and lung diseases with rapid, effective and painless effects. It is becoming more and more popular used in hospital and home. It is reported inhalers have huge market in the world.There are three types of inhalers: Metered-dose Inhalers (MDIs), Dry Powder Inhalers (DPIs) and Nebulizers. MDIs and DPIs have many disadvantages and now are used rarely. Pneumatic or jet nebulizer and ultrasonic nebulizer are conventional nebulizers. These nebulizers have many drawbacks. Such as compressed gas or electrical resource required, poor efficiency and risk of denaturing or reducing the activity of drug solution.The new type Piezoelectrically Actuated Mesh Nebulizers based on MEMS technology are suitable for use in the apartment houses. They have advantage of fine droplets, much greater efficiency, low power, less residual volume, portability and negligible effects of denaturation or activity. Mesh nebulizers have two types: static mesh nebulizer uses a vibration of piezoelectric transducer to push the liquid drug through a static mesh form an aerosol. Vibrating mesh nebulizer use vibration of piezoelectric ceramic transmit to mesh, the vibrating mesh push the liquid drug through the apertures.Characteristic of Piezoelectric materials PZT and theory of transducer and ultrasonic horn are introduced. Model of two new type nebulizers and analysis of aerosol forming are described in this paper. The factor of influence nebulization quality is also described. As widely application of FEA in product design and performance, the finite element method is used to analyze the structure of nebulizers based on the piezoelectric coupling theory.Static, modal and harmonic analysis are used to analyze the vibrating mesh nebulizer in ANSYS. The relationship of maximum displacement between applied voltage and thickness of piezoelectric crystal are got in static analysis. A modal analysis is used to get the frequency and mode of the structure. Harmonic analysis is used to analyze the vibration of the structure through change of thickness, small diameter of piezoelectric cirque plate and damping ratio. A higher frequency design is supplied.Analytic method and FEM is used to analyze the horn of static mesh nebulizer. Longitudinal vibration of the transducer is analyzed. The results show increasing knuckle and reducing end length of the horn can improve nebulzation quality. smaller end diameter of the horn and larger thickness of piezoelectric cirque plate can get larger frequency and displacement. The result of analysis is useful for optimization of the transducers.