Two-dimensional fluid viscosity measurement in microchannel flow using fluorescence polarization imaging
Two-dimensional fluid viscosity measurement in microchannel flow using fluorescence polarization imaging
复制标题
使用荧光偏振成像测量微通道流动中的二维流体粘度
DOI：
10.1088/1361-6501/abeccb
复制
发表时间：
2021
影响因子：
2.4
通讯作者：
Nakabe Kazuyoshi
中科院分区：
文献类型：
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作者：
Kuriyama Reiko;Nakagawa Tomotaka;Tatsumi Kazuya;Nakabe Kazuyoshi
本研究描述了基于荧光偏振显微镜的非接触式二维流体粘度测量技术的发展。该技术利用荧光团旋转布朗运动引起的荧光去偏振，并通过测量稳态荧光偏振来确定微通道流中的流体粘度。该技术的主要优点是可以通过非接触式光学测量来可视化流体粘度的平面分布，而常用的机械粘度计则测量散装液体的粘度。此外，与其他非接触技术（例如时间分辨荧光寿命/偏振测量）相比，稳态偏振测量是使用更简单的实验装置实现的。使用异硫氰酸荧光素标记的酪蛋白分子作为荧光探针，通过实验获得了流体粘度（μ）与荧光偏振度（P）之间的关系。通过将蔗糖或葡萄糖与溶液混合，将流体粘度控制在0.7-3.0 mPa s的范围内，这是生物材料中经常遇到的范围。测量过程中流体温度保持均匀在30℃。校准结果表明，1/P随1/μ线性增加，与理论预测定性吻合。根据校准曲线的斜率，测量不确定度为 7.5%–9.5%。通过应用校准曲线，在均匀温度条件下，Y 形微通道中共同流动的两种溶液之间的质量扩散产生的粘度梯度清晰可见。最后，通过实验评估了温度变化对P的影响。结果支持了本技术对于温度变化引起的粘度分布可视化的适用性。这些结果证实了本技术用于分析与质量传递或温度变化相关的微尺度粘度场的可行性。
This study describes the development of a noncontact and two-dimensional fluid viscosity measurement technique based on fluorescence polarization microscopy. This technique exploits fluorescence depolarization due to rotational Brownian motion of fluorophores and determines fluid viscosity in microchannel flow by measuring steady-state fluorescence polarization. The main advantage of the technique is that planar distributions of fluid viscosity can be visualized by noncontact optical measurement, while commonly-used mechanical viscometers measure the viscosity of bulk liquids. Moreover, steady-state polarization measurements are realized using a simpler experimental setup compared to other noncontact techniques such as time-resolved fluorescence lifetime/polarization measurements. The relationship between the fluid viscosity (μ) and the fluorescence polarization degree (P) was experimentally obtained using casein molecules labeled with fluorescein isothiocyanate as a fluorescent probe. The fluid viscosity was controlled within the range of 0.7–3.0 mPa s, which is the range often encountered in biological materials, by mixing sucrose or glucose with the solution. The fluid temperature was maintained uniform at 30 C during the measurement. The calibration result showed that 1/P linearly increased with 1/μ which qualitatively agreed well with the theoretical prediction. The measurement uncertainty was 7.5%–9.5% based on the slope of the calibration curve. The viscosity gradient generated by the mass diffusion between the two solutions co-flowing in the Y-shaped microchannel was clearly visualized under uniform temperature conditions by applying the calibration curve. Finally, the influence of the temperature change on P was experimentally evaluated. The results supported the applicability of the present technique for visualization of the viscosity distribution induced by temperature change. These results confirmed the feasibility of the present technique for analyzing microscale viscosity fields associated with mass transport or temperature change.