The electric field induced motion of a charged water droplet suspended in a low-dielectric oil medium is exploited to evaluate the rheological properties of the suspending medium. The time-periodic electrophoretic motion of the droplet between the electrodes decorated in a polymeric micro-well is translated into a proof-of-concept microfluidic prototype, which can measure viscosities of the unknown fluid samples. The variations in the instantaneous velocities of the migrating droplet have been measured inside silicone oil of known physical properties at different electric field intensities. Subsequently, a balance between the electric field to the viscous force has been employed to evaluate the experimental charge density on the droplet surface. Thereafter, a comprehensive scaling law has been devised to find a correlation between the charge on the droplet to the dielectric permittivity of the surrounding medium, size of the water droplet, and the applied electric field intensity. Following this, the scaling law and force balance have been employed together to evaluate the unknown viscosity of an array of suspending mediums by simply analyzing the electrophoretic motion of water droplet. The model proposed is also found to be consistent when a solid amberlite microparticle has been employed as a probe instead of the water droplet. In such a scenario, minor changes in the exponents of the scaling law are found to be necessary to reproduce the results obtained using the water droplet. The method paves the way for the making of an economical and portable microfluidic rheometer with further finetuning and translational developments.

中文翻译：

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微流控粘度计：电场下油中水微滴振荡运动的平移

利用悬浮在低介电油介质中的带电水滴的电场感应运动来评估悬浮介质的流变特性。聚合物微孔中装饰的电极之间的液滴的时间周期电泳运动被转化为概念验证微流体原型，该原型可以测量未知流体样品的粘度。在不同电场强度下，在已知物理性质的硅油内部测量了迁移液滴的瞬时速度的变化。随后，采用电场与粘性力之间的平衡来评估液滴表面上的实验电荷密度。此后，已经设计了一个全面的比例定律来发现液滴上的电荷与周围介质的介电常数、水滴大小和施加的电场强度之间的相关性。在此之后，通过简单地分析水滴的电泳运动，结合使用比例定律和力平衡来评估一系列悬浮介质的未知粘度。当使用固体琥珀石微粒代替水滴作为探针时，还发现所提出的模型是一致的。在这种情况下，发现缩放定律的指数的微小变化对于重现使用水滴获得的结果是必要的。