利用液滴指纹图实现溶液折射率的精确测量

Accurate Measurement of Liquid Refractive Index Using Liquid Droplet Fingerprints

提出一种利用光纤-电容液滴分析仪进行溶液折射率精确测量的方法。利用最小二乘法拟合得到与水表面张力近似溶液(NaCl、葡萄糖等)的液滴指纹图第一峰的光纤值与折射率之间的线性模型;仿真分析乙醇、丙醇等与水表面张力相差较大的溶液的表面张力对液滴外形的影响,并提出带表面张力修正的折射率计算模型。实验结果表明,利用所提出的线性模型得到的葡萄糖和NaCl溶液的折射率平均误差为2.9447×10^(-4);利用带表面张力修正的折射率计算模型得到的为1.4381×10^(-4),且测试样品的最大相对误差为0.1258%。该方法对扩展液滴分析仪的适用性和提高其分析精度有一定意义。

An accurate measurement approach to liquid refractive index of liquids with a fiber-capacitance droplet analyzer is proposed. A linear model between first peak values of liquid droplet fingerprints and refractive indexes is built by the least square method, where the surface tensions of glucose solutions and NaC1 solutions are similar to that of water. The refractive index calculation model with surface tension modification is proposed based on the simulation analysis on influence of the surface tensions of ethanol and propanol solutions on droplet shape, where the surface tensions of ethanol solutions and propanol solutions have large difference with that of water. The experimental results show that, the mean error of glucose solutions and NaC1 solutions by the linear model is 2. 9447 × 10^-4 , the mean error of the tested solutions by the refractive index calculation model with surface tension modification is 1. 4381 × 10^-4 , and the maximal relative error of tested solutions is 0. 1258%. The proposed method is meaningful to extend applicability of fiber-capacitance droplet analyzers and improve the accuracy of refractive index measurement.