Athiya Azeem1, Gajendra Singh1, Hak-Kim Chan3, Lunjian Li2, Runyu Yang2, Agisilaos Kourmatzis1
1School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006, Australia
2School of Materials Science and Engineering, UNSW Sydney, NSW 2052, Australia
3School of Pharmacy, The University of Sydney, NSW 2006, Australia
Summary
The lack of predictability in the performance of dry powder inhalers (DPI) has long been a challenge in the field of inhaled drug delivery. This is due to complex interactions between device and powder formulation that remain poorly understood, most notably, in the process of deagglomeration. This study demonstrates an image processing technique that is able to quantify agglomerate to wall collision events using high-speed microscopic images taken from an optically accessible device. Mannitol of particle aerodynamic diameter, d50 = 2.92 µm (M3) and d50 = 4.96µm (M5), at a constant flow rate of 30 SLPM (inlet: 10 m/s) and 60 SLPM (inlet: 20 m/s) were used to compare the effect of particle size distribution and flowrates.
Both flowrate and particle size were found to influence collision frequencies. For M3 powder, an increase in flow rate resulted in a significant increase in collision frequency over the field of view (FOV) examined; however, as the particle size increased, the effect of flow rate diminished. It was also observed that at 30 SLPM the particle size played a more significant role in the frequency of agglomerate-to-wall collisions than they did at 60 SLPM for the location examined in this device.
Additional fields of view must be analysed in conjunction with global imaging to better understand the overall flow behaviour in future. However, these results have demonstrated the utility of advanced image processing in quantitatively characterizing agglomerate-to-wall collision events, which would ultimately correlate with the production of fine particles.
Key Message
A methodology was developed to identify collision frequency of agglomerate-to-wall impaction from high-speed microscopic images. This work demonstrates an ability to quantify significant differences that arise from change in flow rate and powder constituent size. The technique leads to an improved understanding of deagglomeration mechanisms within dry powder inhalers.