Synchrotron X-ray measurements of pressurized metered dose inhaler sprays: enabling improved nozzle design

Daniel J. Duke, Nicholas Mason-Smith, Daniel Edgington-Mitchell, Alan L. Kastengren, Jan Ilavsky, Paul Young, Daniela Traini, David Lewis, Damon Honnery

Research output: Chapter in Book/Report/Conference proceedingConference proceeding contributionpeer-review


In order to tailor the performance of pressurized metered dose inhalers (pMDIs) for a desired particle size distribution, the physical processes inside the spray and the nozzle must be understood in great detail. This necessitates non-invasive, in situ particle and droplet size measurements. This article describes several X-ray diagnostic tools developed for this purpose. X-ray radiography measures the mass of liquid in the spray. X-ray fluorescence measures the drug distribution in the spray, independently of the propellant and any co-solvents. A new technique, ultra-small angle X-ray scattering, also provides a quantitative measurement of total surface area of liquid in the spray. These measurements are combined with traditional laser diffraction techniques to estimate important parameters which are difficult to directly measure, such as droplet composition and liquid volume distribution. Combining these measurement techniques allows us to observe the effects of pMDI formulation on the spray in much greater detail than has previously been possible. The measurements reveal the important role that nozzle exit conditions and near-nozzle evaporative effects have on pMDI sprays, as the composition of the liquid droplets is found to vary significantly in the near nozzle region. A deeper understanding of these phenomena opens up new possibilities for the tailored design of pMDI devices for various drug and propellant combinations.
Original languageEnglish
Title of host publicationRespiratory Drug Delivery 2018
EditorsR. N. Dalby, P. R. Byron, M. Hindle, J. Peart, D. Traini, P. M. Young, S. J. Farr, J. D. Suman, A. Watts
Place of PublicationRichmond, VA
PublisherRDD Online
Number of pages12
ISBN (Electronic)9781942911258
Publication statusPublished - 2018
Externally publishedYes
EventRespiratory Drug Delivery 2018 - Arizona USA, United States
Duration: 22 Apr 201826 Apr 2018


ConferenceRespiratory Drug Delivery 2018
Country/TerritoryUnited States


  • synchrotron
  • X-ray
  • radiography
  • ultra-small angle X-ray scattering
  • pressurized metered dose inhaler (pMDI)
  • spray nozzle


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