| As a relatively new technology,microfluidic technology can greatly shorten the detection time and reduce the detection cost because of its integration and miniaturization.It has received more attention and research in the field of rapid detection.The detection of concentration in chips has always been one of the key and difficult points in microfluidic technology.Traditional detection methods require built-in electrodes,high pressure,or magnetic fields,etc.Due to the flow path and reaction cell on the order of micrometers to millimeters,it is difficult to insert macroscopic detection devices.and micro-detectors such as optics and chromatography are still under research,so it is difficult to miniaturize rapid detectors and popularize microfluidics.With the development of computer vision technology,the image processing method is used to detect the concentration component of the solution in chips.There is no damage or modification to chips,and the solution will not be polluted.Only one optical camera needs to be added,the detection of the solution can be completed,which is a new research idea.In this paper,the image analysis processing and microfluidic technology were combined to quantitatively and rapidly analyze sample concentration based on the principle of biochemical chromogenic reaction,and the application of rapid detection about nitrite in chips was carried out.The details were as follows:(1)Firstly,a two-stage and pen-like microfluidic chip was designed based on the naphthylamine diamine hydrochloride method.The fluid drive method was investigated and the laser processing method of the PMMA material and bonding process were studied.Finally,the microfluidic chip used for nitrite detection was fabricated.(2)The overall design of nitrite detection was carried out.In order to ensure the illumination intensity,the height and the angle of the camera,and the position of chips,a black box was designed as detection system and introduced.(3)The Sobel edge detection method was used for chip edge detection and the image edge projection method was used to accurate locate the edge of the chip;The foreground image binarization threshold was dynamically determined by the gray value mean and the standard variance of the background region,which avoided the poor segmentation effect caused by the fixed threshold;Finally,the image morphology operation was used to eliminate the isolated points and the small lines,then extracted the chromogenic area by band-pass filter and calculated the eigenvalues,which made a good preparation for experimental verification.(4)According to the chip and the image acquisition system,the experimental study of nitrite in the chip was carried out.The experimental results showed that the temperature has little effect on the final result in the range of 15?30?;When the thickness of the chip was 2mm: the primary reaction and chromogenic reaction time were 210 s and 150 s respectively,the detection time was about 10min;The linear range was between 0.5?10mg/L,and the detection limit was 0.8mg/L;The recoveries were 94.1%?108.0%;the sample consumption and reagent consumption were 1/4 and 1/3,1/30 and 1/24 of the spectrophotometry and colorimetry respectively.The platform and method constructed in this paper had the advantages of low cost,short detection time and good repeatability,which can satisfied the needs of rapid detection of nitrite.Figure [37] Table [16] Reference [71]. |
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