Research On Point-of-care Testing Technology And Instrument Based On Smartphone Digital Image Colorimetry

Point-of-care testing(POCT)plays an important role in medical diagnosis,food safety,environmental monitoring and public safety due to its advantages of high real-time detection,no need to rely on professional equipment,and low comprehensive cost.Among them,digital image colorimetry is widely used in real-time detection technology because of its simple operation and quick results.The widespread popularity and performance improvement of smartphones have opened up new ideas for POCT based on digital image colorimetry.However,in practical application,the digital image colorimetric analysis system based on smartphone still has some shortcomings:(1)The unstable external lighting environment and different mobile phone models lead to differences in the obtained colorimetric images,which in turn affects the accuracy of the colorimetric analysis results.This is the key problem to be solved urgently in the colorimetric analysis of digital images of smartphones.(2)In the multi-index colorimetric reaction system,the color information is usually converted into gray value to realize the detection,which leads to the problem of low detection accuracy.(3)In the portable paper-based fluorescence detection system,such as insufficient excitation light source intensity,non-uniformity of excitation light source,and inherent fluorescence background of paper-based fluorescence analysis are the pain points that affect the sensitivity and accuracy of paper-based fluorescence analysis,and these are also the biggest challenges to improve the signal-to-noise ratio of paper-based fluorescence analysis.In this research,we work from the aspects of colorimetric system,biochemical sensor preparation,biochip design,detection hardware system and software system to solve the problems of smartphone digital image colorimetry and realize its application in point-of-care detection technology.The specific research contents are as follows:1.According to research,pH color development belongs to the color development system in which the color tone changes.Taking pH detection as an example,a new colorimetric analysis index of color "dominant wavelength" is proposed for the color rendering system with changing hue.In view of the influence of different factors such as external ambient light and mobile phone model on the colorimetric analysis of smartphone digital images,an integrated optical system was designed,and a color correction algorithm was developed.Aiming at the low detection accuracy of pH test paper,the cumbersome operation of traditional pH meter,and the large amount of reagents,a new method for pH measurement that combines smartphones and pH test strips is proposed.By establishing the corresponding relationship between the pH value and the dominant wavelength value,the high-precision measurement of the pH value is realized,and the detection accuracy reaches 0.05 pH units.The actual samples were measured by the detection system and the pH meter respectively,and the detection results of the two were analyzed by constructing a Bland-Altman diagram.The difference between the measured values of the two detection methods is within the range of ±1.96 SD,which verifies the accuracy and reliability of the system in the determination of pH value.The detection system cleverly combines commercial test strips with smartphone digital image colorimetric analysis,providing a new platform for fast and high-precision on-site pH measurement in immediate medical diagnosis,environmental monitoring and other fields.2.The influence of factors such as external light environment in the application process of smartphone digital image colorimetry is solved.By establishing an accurate analysis method for multi-index multi-colorimetric parameters,a smartphone-based array test strip urine multiindex quantitative detection system was developed.Routine urine examination is one of the "three routines" items of medical examination.It is of great significance to the clinical diagnosis,treatment judgment and long-term monitoring of chronic diseases such as metabolic system diseases and kidney diseases.It is imperative to develop a home urine routine detection system.In this chapter,a smartphone-based array test strip urine multi-index quantitative detection system is innovatively developed by combining smartphones with commercial urine test strips.Through the layout design of the 3×3 array test strips,it can not only quantify multiple indicators at the same time,but also make it easier to obtain uniform illumination required for colorimetric analysis while reducing the size of the device.According to the color change characteristics of 9 urine indicators,the optimal chromaticity value was selected for "one-click" quantitative detection.Taking the spiked samples of glucose,microalbumin,and creatinine as an example,the results were compared with the detection results of UV spectrophotometer,and the consistency reached more than 98%.In order to evaluate the reliability and practicality of the system,urine routine indexes of 100 actual samples were detected by the detection system and H-800 Urine Analyser in the hospital,respectively.The ROC curve was used to analyze the high consistency of the detection results of the two methods.As a urinalysis screening technology based on mobile platform,the system provides a new scheme and means for urine indicators home detection,and has great practical application value.3.To further improve the detection sensitivity,the Zn O nanowire paper-based fluorescence sensing platform for smartphones was developed.Compared with ordinary filter paper,the low fluorescence background of glass fiber filter paper makes it more suitable for quantitative fluorescence analysis.In this study,Zn O nanowires were synthesized on glass filter paper for the first time by "hydrothermal method",which achieved fluorescence enhancement and solved the problem of low signal-to-noise ratio in paper-based fluorescence detection.Combined with paper-based microfluidic technology,a high-throughput array fluorescent biochip was successfully prepared.A portable fluorescence sensing analyzer has been developed.By cleverly designing a ring-shaped patch-type excitation light source,the pain points of the portable fluorescence sensing platform such as insufficient excitation light source intensity and uneven excitation have been solved.At the same time,the smartphone fluorescence array detection software “H-T Fluorescence Detect” was developed to achieve accurate acquisition and analysis of fluorescence images.The high-throughput fluorescence detection system was validated using polymer quantum dots CN-PPV,which demonstrated the feasibility of fluorescence enhancement of Zn O nanowires to improve the detection sensitivity.Finally,the quantitative detection of rabbit Ig G was realized by using the developed smartphone-based high-throughput paper-based microfluidic fluorescence analysis device.The experimental results show that the detection limit of rabbit Ig G on the Zn O nanowire paper is 10 times higher than that of pure glass filter paper,which verifies the reliability of the detection system.This smartphone-based paper-based immunofluorescence sensing platform does not require complicated preparation procedures.The low background and fluorescence enhancement of Zn O nanowires on glass filter paper provide a new method for high signal-to-noise ratio and high sensitivity biochemical molecular detection,which has broad application prospects in the fields of medical diagnosis,food safety and environmental monitoring.