Simultaneous imaging of temperature and concentration of ethanol-water mixtures in microchannel using near-infrared dual-wavelength absorption technique
Simultaneous imaging of temperature and concentration of ethanol-water mixtures in microchannel using near-infrared dual-wavelength absorption technique
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DOI：
10.1088/0957-0233/27/11/115401
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发表时间：
2016-11-01
影响因子：
2.4
通讯作者：
Yamada, Yukio
中科院分区：
文献类型：
--
作者：
Kakuta, Naoto;Yamashita, Hiroki;Yamada, Yukio
提出了一种微流控通道中乙醇-水混合物温度和乙醇浓度的同时成像方法。该原理基于以下事实：在1905 nm波长处的吸光度取决于水的温度，而在1935 nm处的吸光度与温度无关，但强烈地取决于水的摩尔浓度，水的摩尔浓度与混合物中乙醇的摩尔浓度成反比。通过交替照射系统和近红外（NIR）相机交替采集两个波长下的吸光度图像，每个以每秒50帧的速度采集，然后通过线性回归模型转换为温度和浓度图像。将成像方法应用于具有0.43M的乙醇浓度的稀乙醇-水混合物和在温度控制的Y通道中并排流动的水。浓度图像清楚地显示了混合物和水流之间的差异，并且两股水流之间的横向浓度梯度通过相互扩散而向下游减小。还证实了互扩散系数随着温度的升高而增加。温度图像显示，由于流体与通道材料之间的热传递，立即形成均匀分布。
This paper presents a simultaneous imaging method of temperature and ethanol concentration of ethanol-water mixtures in microfluidic channels. The principle is based on the facts that the absorbance at a wavelength of 1905 nm is dependent on the temperature of water and that the absorbance at 1935 nm is independent of the temperature but strongly dependent on the molar concentration of water, which is reciprocal to the molar concentration of ethanol in the mixture. The absorbance images at the two wavelengths were acquired alternately, each at 50 frames per second, by an alternate irradiation system and near-infrared (NIR) camera, and then converted to the temperature and concentration images by a linear regression model. The imaging method was applied to a dilute ethanol-water mixture with an ethanol concentration of 0.43M and water flowing side by side in a temperature-controlled Y-channel. The concentration images clearly showed differences between the mixture and water streams, and that the transverse concentration gradient between the two streams decreased downstream by mutual diffusion. It was also confirmed that the mutual diffusion coefficient increased as the temperature increased. The temperature images showed that uniform distributions were immediately formed due to heat transfer between the fluid and channel materials.