Lammertse Evan, Koditala Nikhil, Sauzade Martin, Li Hongxiao, Li Qiang, Anis Luc, Kong Jun, Brouzes Eric
Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794 USA.
Department of Mathematics and Statistics, Department of Computer Science, Georgia State University, Atlanta, GA 30302 USA.
Microsyst Nanoeng. 2022 Jul 1;8:72. doi: 10.1038/s41378-022-00404-z. eCollection 2022.
Advances in microfluidic technologies rely on engineered 3D flow patterns to manipulate samples at the microscale. However, current methods for mapping flows only provide limited 3D and temporal resolutions or require highly specialized optical set-ups. Here, we present a simple defocusing approach based on brightfield microscopy and open-source software to map micro-flows in 3D at high spatial and temporal resolution. Our workflow is both integrated in ImageJ and modular. We track seed particles in 2D before classifying their Z-position using a reference library. We compare the performance of a traditional cross-correlation method and a deep learning model in performing the classification step. We validate our method on three highly relevant microfluidic examples: a channel step expansion and displacement structures as single-phase flow examples, and droplet microfluidics as a two-phase flow example. First, we elucidate how displacement structures efficiently shift large particles across streamlines. Second, we reveal novel recirculation structures and folding patterns in the internal flow of microfluidic droplets. Our simple and widely accessible brightfield technique generates high-resolution flow maps and it will address the increasing demand for controlling fluids at the microscale by supporting the efficient design of novel microfluidic structures.
微流控技术的进步依赖于工程化的三维流动模式，以便在微观尺度上操控样本。然而，当前用于绘制流动的方法仅提供有限的三维和时间分辨率，或者需要高度专业化的光学装置。在此，我们提出一种基于明场显微镜和开源软件的简单散焦方法，以高空间和时间分辨率对微流进行三维绘制。我们的工作流程既集成于ImageJ中，又具有模块化特点。我们先在二维中追踪种子粒子，然后使用参考库对其Z位置进行分类。我们比较了传统互相关方法和深度学习模型在执行分类步骤时的性能。我们在三个高度相关的微流控示例上验证了我们的方法：一个通道阶跃扩展和位移结构作为单相流示例，以及液滴微流控作为两相流示例。首先，我们阐明位移结构如何有效地使大粒子跨流线移动。其次，我们揭示了微流控液滴内部流动中新颖的再循环结构和折叠模式。我们这种简单且易于获取的明场技术可生成高分辨率的流动图谱，并且通过支持新型微流控结构的高效设计，将满足在微观尺度上控制流体的日益增长的需求。
