title: Powder dispersion mechanisms within a dry powder inhaler using microscale particle image velocimetry.
abstract: The goal of this work was to evaluate the ability of Particle Image Velocimetry (PIV) to visually assess dry powder dispersion within an inhaler. Herein, the study reports particle movement characterization of entrained low-micron particles within an inhaler to further scheme of potential mechanisms. Carrier based DPI formulations were prepared and placed in a transparent model Rotahaler®chamber for the aerosolization experiments. Then using the PIV, a high-speed camera, the dried powder dispersion was directly observed and analyzed for all, neat, binary and ternary systems. Powder dispersion mechanisms proposed include drag force, impact with obstacle and particle-particle collision; these different mechanisms depended on the powder flow properties. A revised ratio of aerodynamic response time (τA) to the mean time between collisions (τC) was found to be 6.8 indicating that particle collisions were of strong influence to particle dispersion. With image analysis techniques, visualization of particle flow pattern and collision regions was possible; suggesting that the various mechanisms proposed did govern the powder dispersion.
authors: Department of Pharmacy, National University of Singapore, Singapore.
authors: Xiang
authors: X
authors: Kou
authors: Department of Mechanical Engineering, Purdue University, USA.
authors: Steven T
authors: ST
authors: Wereley
authors: Department of Pharmacy, National University of Singapore, Singapore.
authors: Paul W S
authors: PW
authors: Heng
authors: Department of Pharmacy, National University of Singapore, Singapore.
authors: Lai Wah
authors: LW
authors: Chan
authors: Agricultural and Biological Engineering, Purdue University, USA. Electronic address: tcarvaja@purdue.edu.
authors: M Teresa
authors: MT
authors: Carvajal
mesh_terms: D000280:Administration, Inhalation; D000336:Aerosols; D004339:Drug Compounding / Q000379:methods*; D058995:Dry Powder Inhalers; D005079:Excipients; D007785:Lactose; D010316:Particle Size; D011208:Powders; D012212:Rheology / Q000379:methods*; D013499:Surface Properties
chemical_list: D000336:Aerosols; D005079:Excipients; D011208:Powders; D007785:Lactose
keywords: Collision; DPI; Dispersion mechanism; Image analysis; Impact; PIV