Fishler Rami, Ostrovski Yan, Lu Chao-Yi, Sznitman Josué
Department of Biomedical Engineering, Technion - Israel Institute of Technology, 32000 Haifa, Israel.
Department of Biomedical Engineering, Technion - Israel Institute of Technology, 32000 Haifa, Israel.
J Biomech. 2017 Jan 4;50:222-227. doi: 10.1016/j.jbiomech.2016.11.043. Epub 2016 Nov 13.
The dispersion of inhaled microparticles in the pulmonary acinus of the lungs is often attributed to the complex interplay between convective mixing, due to irreversible flows, and intrinsic particle motion (i.e. gravity and diffusion). However, the role of each mechanism, the exact nature of such interplay between them and their relative importance still remain unclear. To gain insight into these dispersive mechanisms, we track liquid-suspended microparticles and extract their effective diffusivities inside an anatomically-inspired microfluidic acinar model. Such results are then compared to experiments and numerical simulations in a straight channel. While alveoli of the proximal acinar generations exhibit convective mixing characteristics that lead to irreversible particle trajectories, this local effect is overshadowed by a more dominant dispersion mechanism across the ductal branching network that arises from small but significant streamline crossing due to intrinsic diffusional motion in the presence of high velocity gradients. We anticipate that for true airborne particles, which exhibit much higher intrinsic motion, streamline crossing would be even more significant.
吸入性微粒在肺腺泡内的扩散通常归因于不可逆流动引起的对流混合与微粒固有运动（即重力和扩散）之间的复杂相互作用。然而，每种机制的作用、它们之间这种相互作用的确切性质及其相对重要性仍不清楚。为了深入了解这些扩散机制，我们追踪液体悬浮的微粒，并在一个受解剖学启发的微流体腺泡模型中提取它们的有效扩散率。然后将这些结果与直通道中的实验和数值模拟进行比较。虽然近端腺泡代的肺泡表现出导致微粒轨迹不可逆的对流混合特征，但这种局部效应被导管分支网络中更占主导地位的扩散机制所掩盖，这种机制源于在存在高速梯度的情况下，由于固有扩散运动而产生的小而显著的流线交叉。我们预计，对于具有更高固有运动的真正空气传播微粒，流线交叉将更加显著。
