Ranchon Hubert, Picot Vincent, Bancaud Aurélien
1] CNRS, LAAS, 7 avenue du colonel Roche, F-31400 Toulouse, France [2] Univ de Toulouse, LAAS, F-31400 Toulouse, France.
Sci Rep. 2015 May 14;5:10128. doi: 10.1038/srep10128.
The manipulation of fluids in micro/nanofabricated systems opens new avenues to engineer the transport of matter at the molecular level. Yet the number of methods for the in situ characterization of fluid flows in shallow channels is limited. Here we establish a simple method called nanoparticle velocimetry distribution analysis (NVDA) that relies on wide field microscopy to measure the flow rate and channel height based on the fitting of particle velocity distributions along and across the flow direction. NVDA is validated by simulations, showing errors in velocity and height determination of less than 1% and 8% respectively, as well as with experiments, in which we monitor the behavior of 200 nm nanoparticles conveyed in channels of ~1.8 μm in height. We then show the relevance of this assay for the characterization of flows in bulging channels, and prove its suitability to characterize the concentration of particles across the channel height in the context of visco-elastic focusing. Our method for rapid and quantitative flow characterization has therefore a broad spectrum of applications in micro/nanofluidics, and a strong potential for the optimization of Lab-on-Chips modules in which engineering of confined transport is necessary.
在微纳制造系统中对流体进行操控，为在分子水平上设计物质传输开辟了新途径。然而，用于原位表征浅通道中流体流动的方法数量有限。在此，我们建立了一种称为纳米颗粒测速分布分析（NVDA）的简单方法，该方法基于宽视场显微镜，通过拟合沿流动方向和垂直于流动方向的颗粒速度分布来测量流速和通道高度。NVDA 通过模拟得到验证，结果表明速度和高度测定的误差分别小于 1%和 8%，同时也通过实验得到验证，在实验中我们监测了在高度约为 1.8μm 的通道中传输的 200nm 纳米颗粒的行为。然后，我们展示了该检测方法对于表征鼓胀通道中流动的相关性，并证明了其在粘弹性聚焦背景下表征通道高度上颗粒浓度的适用性。因此，我们这种快速定量流动表征方法在微纳流体中有广泛的应用，并且在需要对受限传输进行工程设计的芯片实验室模块优化方面具有强大潜力。
