Simultaneous viscosity and density measurement of small volumes of liquids using a vibrating microcantilever.
Simultaneous viscosity and density measurement of small volumes of liquids using a vibrating microcantilever.
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DOI：
10.1039/c6an02674e
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发表时间：
2017-05-02
期刊：
影响因子：
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通讯作者：
Voïtchovsky K
中科院分区：
文献类型：
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作者：
Payam AF;Trewby W;Voïtchovsky K
推导出一个分析模型来计算的粘度和密度的小体积的流体从浸没微悬臂梁的谐振频率。它的准确性验证了简单和非牛顿流体。许多工业和技术应用需要精确测定液体的粘度和密度。这种测量可能很耗时，并且通常需要对大量液体进行采样。这些问题可以通过使用微悬臂梁来部分地克服，但是大多数现有的方法依赖于悬臂梁的特定几何形状和性质，这使得简单、准确的测量变得困难。在这里，我们提出了一种新的方法，能够同时量化的密度和微升液体的粘度。该方法完全基于浸没微悬臂梁的两个特征频率的测量，完全独立于悬臂梁的选择。我们推导出液体的密度和粘度的解析表达式，并验证我们的方法与几个简单的液体和不同的杠杆。我们的模型的非牛顿流体的应用表明，计算出的粘度是非常强大的相比，从一个标准的流变仪获得的测量。然而，结果变得越来越依赖于悬臂的几何形状，因为液体的粘度的频率依赖性变得更加显著。
An analytical model is derived to calculate the viscosity and density of small volumes of fluid from the resonance frequencies of an immersed microcantilever. Its accuracy is verified on simple and non-Newtonian fluids. Many industrial and technological applications require precise determination of the viscosity and density of liquids. Such measurements can be time consuming and often require sampling substantial amounts of the liquid. These problems can partly be overcome with the use of microcantilevers but most existing methods depend on the specific geometry and properties of the cantilever, which renders simple, accurate measurement difficult. Here we present a new approach able to simultaneously quantify both the density and the viscosity of microliters of liquids. The method, based solely on the measurement of two characteristic frequencies of an immersed microcantilever, is completely independent of the choice of a cantilever. We derive analytical expressions for the liquid's density and viscosity and validate our approach with several simple liquids and different cantilevers. Application of our model to non-Newtonian fluids shows that the calculated viscosities are remarkably robust when compared to measurements obtained from a standard rheometer. However, the results become increasingly dependent on the cantilever geometry as the frequency-dependent nature of the liquid's viscosity becomes more significant.