Effect of inflow conditioning for dry powder inhalers

Gajendra Singh, Albyn Lowe, Athiya Azeem, Shaokoon Cheng, Hak-Kim Chan, Ross Walenga, Agisilaos Kourmatzis

Research output: Contribution to journalArticlepeer-review


The transport of pharmaceutical dry powder inside an optically accessible inhaler-like device is studied using both macro- and microscopic high-speed imaging. The investigation aims to systematically study the effect of inflow modifications on the dispersion characteristics of agglomerates inside a dry powder inhaler (DPI) geometry. An inhaler device was designed with geometrical features akin to commercial inhalers used in the current market and research oriented inhalers such as the Twincer®: two offset inlet channels (one with a powder pocket), a clockwise swirling chamber and a single outlet channel. At the device outlet, a vacuum pump was fitted with an actuator and calibrated to achieve a steady state inhalation with a peak flowrate of 85 and 125 L/min. Airflow conditions at the intake of the device were strategically perturbed in order to induce powder fluidisation and dispersion using turbulence grids and through physically obstructing channel streams in order to achieve changes in flow behaviour (e.g., flow separation). Complete fluidisation of the powder bed was observed with image processing enabling statistics on de-agglomerated fragment size and velocity. A range of behaviour was noted including local turbulence through introduction of a grid, bimodal fragment size behaviour for cohesive mannitol powder, as well as introduction of low velocity zones in the device through flow splitting. The geometry enables simple systematic study of inflow conditions into a DPI-like device with the data being useful for study of a given powder formulation (mannitol) and validation of computational models.
Original languageEnglish
Article number121085
Pages (from-to)1-15
Number of pages15
JournalInternational Journal of Pharmaceutics
Publication statusPublished - 25 Oct 2021


  • Dry powder inhaler
  • Swirl
  • Turbulence grid
  • Pharmaceutical drug


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