The Research And Impelementation Of Portable Colloidal Gold Detector Based On The Silicon Photocell

With the continuous development of social market economy,people's living consumption level gradually improve,food for people to choose is also more and more,but the food security problem also appeared one after another.For example,a few years ago "sweet" event,"poison ginger" incident and the latest "zombie meat" events,etc.Therefore,it is urgent to develop a kind of instrument which can quickly detect toxic and harmful substances in food.A portable colloidal-gold immunochromatographic strip detector was developed in this paper.It was a food safety testing instrument which make quantitative analysis the concentration of the analyte based on Lambert-Bill law of light absorption.One photodiode-silicon photocell of the instrument was used to receive the reflected light of colloidal gold in the strip.It was deal with the sampling value of the test area in the correlation algorithm.Finally,by using the standard curve,the concentration of the analyte was detected.The research works were studied as the following.(1)Firstly,after analyzing the existing domestic and foreign detection scheme of fast food safety testing,the Lambert-Bill law of light absorption was selected as the theoretical basis.Based on the photoelectric signal conversion technology,one portable colloidal-gold detector was developed to make quantitative analysis of the colloidal-gold immunochromatographic strip.(2)Secondly,the monochrome green light LED with the wavelength of 525 nm was used as the light source in the instrument.The screw stepper motor was used to drive the detection unit to scan the test area of the colloidal-gold immunochromatographic strip.One photodiode-silicon photocell of the instrument was used to receive the reflected light of colloidal gold in the strip.The signal was amplified by two stage amplifier circuit module,and analog to digital conversion by 12-bit A/D converter module,the waveform of the reflected light was obtained finally.(3)After that,the hardware circuit design of portable colloidal gold detector was completed.STM32F103ZET6 microcontroller was used as the core of the whole detection system logic control and data processing.At the same time,the Micro SD card was selected to save the test results in the form of FATFS file system.The combination of membrane keypad and TFT LCD screen was perfected to bring the simple and friendly interactive experience.Through the external thermal printer,it can print the current test results at any time.(4)In the end,The ratio of the area of the measurement could be processed by area method or height method.According to the relationship between the concentration of standards and its detection ratio of the curve fitting,the concentration of the analyte was determined.The experimental results were shown that the developed portable colloidal gold detector had high stability and was achieved the expected design goal.