Grid-induced aerosol optimization in pMDIs: A multiscale design, simulation, and experimental study
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
Conventional pressurized metered dose inhalers (pMDIs) often face challenges in efficiently delivering therapeutic aerosols for the treatment of pulmonary diseases. This study proposes a novel design enhancement: the integration of a grid screen at the outlet of a standard pMDI actuator, supported by a slender 0.8 mm wire. Two grid configurations were developed and tested: (1) a uniform grid with 5 µm pores, and (2) a non-uniform grid where pore diameters increase from 3 µm at the edges to 8 µm at the center. Both configurations were evaluated on straight and curved substrates, maintaining a consistent solidity fraction of 61 %. Spray dynamics were modeled using a coupled computational framework that combines the volume of fluid (VOF) and discrete phase models (DPM). This hybrid approach effectively captures droplet deformation upon impact with the grid screen, followed by their transition into discrete-phase droplets. The trajectories of the resulting droplets were then tracked through a medium-sized mouth-throat (MT) geometry, specifically, the Virginia Commonwealth University (VCU) model, utilizing a particle data transmission method (PDTM). To validate the simulation results, grid screens were fabricated and experimentally tested using a next-generation impactor (NGI) to quantify MT aerosol deposition. Among the four configurations tested, the non-uniform straight grid exhibited the most significant performance improvement. It achieved approximately a 50 % reduction in plume velocity, resulting in lower spray kinetic energy. Additionally, the mass median diameter (MMD) decreased from 3.0 µm to 1.6 µm, attributed to a dual mechanism of mechanical jet disruption and thermally enhanced evaporation. The corresponding reduction in the Weber (We) number indicated a substantial decrease in splash-prone droplets, thereby promoting droplet characteristics that are favorable for deeper lung deposition. Overall, drug delivery efficiency improved by up to 35 %, with a reasonable agreement between computational and experimental results (RMSE = 9.88 %). Furthermore, durability testing under a high-frequency chronic obstructive pulmonary disease (COPD) rescue-use protocol demonstrated stable grid performance for up to three consecutive days, beyond which routine cleaning is recommended to maintain optimal functionality.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it