Numerical Simulation And Experimental Research On Active Dry Powder Inhaler

In recent years,due to the rapid expansion of the population of patients with lung diseases such as asthma and chronic obstructive pulmonary disease（COPD）,pulmonary drug delivery has been vigorously developed for its remarkable curative effect and non-invasive treatment.As an important device for pulmonary drug delivery,the development of Dry Powder Inhaler（DPI）has attracted particular attention.Active DPI relies on external power to delivery aerosol,which has good drug dispersion performance and low dependence on patient inhalation airflow.The market prospects of active DPI are bright but current study on the active DPI devices is inadequate due to the difficulty on the research and development.This study aims to research on the performance of a new type of capsule-based active DPI through in vitro experiments and numerical simulation methods,including the emptying ability,dispersion ability and delivery ability of the device.Numerical simulation results show that the relative positions of the air inlet and outlet have a great impact on the emitted dose（ED）fraction of the device.And the increase in the inlet flow rate within a certain range of changes is conducive to improving the emptying rate of the device.Also there is a correlation between the flow field parameters and the emptying rate of the device.Increasing the turbulence intensity of the flow field and the wall shear force are beneficial to the escape of particles in the device.The in vitro test results show that the overall dispersion performance of the active DPI device is better than the passive DPI Handihaler^?.Furthermore,relatively long distance for aerosol dispersion at the outlet of the active DPI device is observed（87 mm at most）and the overall change of mist width along the dispersion direction is relatively gentle（the mist width sharply increases near the outlet of the device）,where the maximum mist width is about 35 mm.Regarding the delivery capability of active DPI,it is found that the higher the inhalation flow rate and the larger the particle size delivered by the device,the higher the deposition fraction in the mouth and throat by analyzing the particle throat deposition fraction and distribution morphology.Moreover,the mist storage area can effectively reduce the airflow velocity into the mouth and throat,thereby reducing collision deposition in the oral cavity.In addition,the initial conditions of the particles delivered by the device at the mouth and throat entrance have a significant impact on the deposition rate of the mouth and throat.This work systematically studies the emptying and delivery behavior of an active DPI device,which provides an important reference basis for the device development,structure optimization and performance evaluation of dry powder inhalers.Furthermore,the comparison of the dry powder aerosolization performance between the active and passive DPIs is conducted,which provides a data reference for the selection and application of future inhalation devices.