为了实现降钙素原浓度的定量测量, 设计了基于树莓派的CMOS图像传感器胶体金试纸条显色分析仪, 对胶体金试纸条拍照获取试纸显色反应的图像颜色特征量。首先, 根据降钙素原胶体金试纸条的显色特性对CMOS传感器进行合理的白平衡校正, 使CMOS传感器具有较好的色彩还原性。然后, 为解决不同设备间颜色管理的差异, 通过对NCS标准色卡拍照, 利用多项式回归法建立了图像传感器RGB空间到XYZ空间的模型, 并对仪器进行了颜色特性化校正。最后, 针对试纸显色不均匀的问题, 经过图像处理后, 选择显色区域内具有代表性的像素点建立图像颜色特征量与样本浓度值的数学模型, 实现了待测样本浓度的精确测量。实验结果表明, 该胶体金试纸条显色分析仪的精度可达93.8%, 重复测量误差小于1.5%, 有效测量范围为0.1~35 ng/mL。该分析仪成本低、测量速度快, 具有一定的应用价值。

The semi-quantitative method of Colloidal gold strip detection by colorimetric principle is widely used in biomedical diagnosis. To achieve quantitative measurement of calcitonin concentration, a CMOS color analytical reader based on raspberry Pi was designed for the acquisition of color characteristics of chromogenic reaction by taking a picture of colloidal gold strip. According to the color characteristics of procalcitonin colloidal gold test strips, the CMOS sensor was corrected by proper white balance parameter adjustment, which enabled the CMOS image sensor has a better color restoration property. In order to eliminate the difference of color management between different devices, the mathematical model of the sensor from RGB space to XYZ space was established via polynomial regression by taking pictures of NCS standard color cards. Thus the instrument was adjusted in color characteristics. Then, the mathematical model of XYZ values and concentration values of the samples was derived from the representative gray value pixel areas of the processed images, thereby the color uniformity problem was solved and the concentration was accurately measured. The experiment results show that the measuring precision can be as high as 93.8%, the repeated measurement error is less than 1.5% and the effective measurement range is from 0.1 ng/mL to 35 ng/mL. With the virtues of cost effective and high measurement speed, the analyzer has a promising application prospect.