Fragmentation dynamics of single agglomerate-to-wall impaction

Effect of inflow conditioning for dry powder inhalers

“…Four dry powders are employed in this study: three spray-dried mannitol powders "M3", "M5" and "M7" with D50 = 2.92, 4.96 and 6.77 μm respectively and a lactose carrier SV010 The reader should note that the agglomerate strength is lowest for M7 followed by M5 [22]. For M3, the agglomerate strength is highest among all the tested powders.…”

“…For M3, the agglomerate strength is highest among all the tested powders. For detailed powder properties, the reader is directed elsewhere [22]. Spherical mannitol particles were produced via a spray dryer (Buchi 290, Flawil, Switzerland) with an inlet air temperature of 140 °C, aspiration set at max 38 m 3 /h and an atomising air rate of 800 NL/h (for full spray drying conditions, refer to [22]).…”

“…For detailed powder properties, the reader is directed elsewhere [22]. Spherical mannitol particles were produced via a spray dryer (Buchi 290, Flawil, Switzerland) with an inlet air temperature of 140 °C, aspiration set at max 38 m 3 /h and an atomising air rate of 800 NL/h (for full spray drying conditions, refer to [22]). The direct control of constituent particle population size was achieved by varying the feed concentration of raw mannitol in de-ionised water (>2 MΩm resistivity at 25 °C, obtained from the Modulab Type II Deionization System, Continental Water System) from 4 to 18 mg/mL and feed rate into the atomiser set to 3.8-8 mL/min.…”

“…Binarization enables the identification of the interface between individual powder fragments and air. The uncertainties owing to the single pixel threshold used in this paper has been extensively studied in previous work that reported an error of 5-10 % in Sauter mean Diameter when compared with phase Doppler anemometry results [32,33,34,35,36,22]. The image processing methodology adapted here limits the optical spatial resolution to 5.016 μm per pixel and a minimum measurable fragment size of approximately 21 μm.…”

“…Recently, the effect of powder properties has been summarized by Mohammad et al in their study of high dose delivery inhalers concerning tuberculosis treatment [19]. Complementing these have been a number of more fundamental studies investigating de-agglomeration and fluidisation processes of DPI powders in more simplified geometries [1,11,20,21,22,18]. What is, however, currently lacking in this space is a more systematic understanding of how certain key design features present in a DPI-like geometry influence subsequent fluidisation and deagglomeration processes inside the device.…”