Microparticle Transport and Sedimentation in a Rhythmically Expanding Alveolar Chip

Abstract

Understanding the mechanism of particle transport and sedimentation in pulmonary alveolus is important for deciphering the causes of respiratory diseases and helping the development of drug delivery. In this study, taking advantage of the microfluidic technique, an experimental platform was developed to study particle behavior in a rhythmically expanding alveolar chip for a sufficient number of cycles. The alveolar flow patterns at different generations were measured for two cases with the gravity direction parallel or vertical to the alveolar duct. Affected by both the vortex flow inside the alveoli and the shear flow in the duct simultaneously, it was observed that particles inside the alveoli either escaped from the inlet of the alveolar duct or stayed in the alveoli, revealing the irreversibility of particle transport in the alveoli. At the earlier acinar generations, particles were inclined to deposit on the distal alveolar wall. The settling rates of particles of different sizes in the alveoli were also compared. This study provides valuable data for understanding particle transport and sedimentation in the alveoli.

Design of a multilayer lung chip with multigenerational alveolar ducts to investigate the inhaled particle deposition

“…The approximate formula for C c when d p > 0.1 μm is C c = 1 + 2.52 λ / d p , where λ is the mean free path of the molecules in the fluid ( λ = 60 nm for air). 37 As the particle size increases, this factor approaches 1. Measurements showed that a fraction of the aerosols in this experiment were less than 0.5 μm in diameter (see Fig.…”

“…However, the tracer aerosols were nebulised from the aqueous solution suspended with fluorescent polystyrene microspheres; therefore, the observed concentrations of aerosol particles differed from those in the real respiratory tract. Recently, Zhu and colleagues [35][36][37] developed an alveolar chip with a single alveolus in which the trajectories of silver particles in the glycerol/water solution were recorded to simulate the aerosols in airflows. Nevertheless, they did not take into account passive breathing in the lung, and the single alveolus configuration only partially reproduced the particle deposition in the multigenerational respiratory bronchioles.…”