Research On SOC-Based Fast Detection System For E.coli

Food is the survival and development of people the most basic material needs,and the necessities of our daily lives. In recent years, along with China’s rapideconomic development, food industry has also ushered in unprecedented prosperity,but at the same time it also brings a series of food safety issues, always threatening us.Food safety issues related to the health of each person affects the nerve of the wholesociety, in relation to national stability, people’s solidarity, it can be said that thecurrent food safety issues is desperately needed to solve. Microbiologicalcontamination problems in the recent food safety issues can not be ignored, especiallyE. coli contamination, the E. coli contamination events occurred throughout almostthe whole of Europe last year, let us see its power. This paper is designed a set ofquickly and accurately detect the E. coli system to solve this problem.The system uses fluorescence analysis as the theoretical basis of the entiresystem. When the specific wavelengths of ultraviolet irradiation to the surface of E.coli sample solution, due to the absorption of UV energy it can jump to the higherenergy level into the excited state, because the higher energy level is not stable, it willbe a transition back from the higher energy level to the lower energy levels with avariety of colors and different intensity of visible light emitting in a very short periodof time, and as soon as you stop the ultraviolet radiation, luminous phenomenon willdisappear immediately, this light is called fluorescence. Because the molecularstructure of various materials are different, when they are irradiated by UV theabsorption wavelength of the light emission and the fluorescence wavelength are alsodifferent, take advantage of its this character, it can be characterized to identify thematerial. Material with the same molecular structure under the same wavelength ofthe excitation light irradiation can emit the same wavelength fluorescence.If theconcentration of this material is different, then the greater the concentration, thestronger the emitted fluorescence intensity, take advantage of this character to thequantitative determination. This use of fluorescence for qualitative and quantitativeanalysis method is called fluorescence analysis, the system is to use it to detect E.coli. The working process of the whole system is366nm wavelength UVlight-emitting diodes as the light source irradiating sample solution, the receiver usinga high sensitivity photomultiplier tube as a media converter converts the optical signalto current signal, after the current-voltage amplifier by ICL7650, AD623, and othercomponents to amplify the signal, then12-bit ADC to convert analog signals to digitalsignals, Finally the core processor C8051F020microcontroller controls the entiresystem, output the test results to the LCM240128LCD screen, The system isequipped with mini-printers and matrix keyboard for easy operation. In addition thesystem in order to facilitate the user data storage and inquires the data storage and joinAT24C512and real time clock chip SD2200, they all support the I~2C bus interface tofacilitate single-chip operation and control.We use C language to write programs for the software of the system, and by usingU-EC5simulators in Keil uVision2compiler environment on the system fordebugging to complete system measurement, display, inquiry, printing, functionsetting, and so on. It will establish good man-machine interface. In order to verify theperformance of the entire system after the completion of the entire design, we havedone a lot of targeted experiments in this period time. All E. coli solution samples areconfigured by myself, and then we used the constant temperature water bath forculturing E. coli.Finally, we did the measurement data for collation, analysis andprocessing, to prove the reliability and stability of the entire system. Whether thesoftware or the hardware of the entire system are running well, it can be applied in life,food, health, customs, environmental monitoring and other fields, the system has agood prospect.