Research And Design Of Impedance Biosensor System

The food pathogens is an important factor in food safety threat, so the detection ofpathogens in food to ensure food security is of great significance.In order to detect the content of harmful substances in food quickly and accurately, todesign a fast, quantitative and simultaneous detection of multiple pathogens in food indeximpedance biosensor system that is simple, fast and accurate, easy-to-line and so on.Detection system STC89C52microcontroller core, including keyboard input analyte species,pathogens analytical measurement circuit with a network analyzer AD5933chip impedancevalues at different concentrations, the resistance-voltage conversion circuit and a voltageamplification circuit, A/D converter processing, LCD display and limit alarm and softwaredesign. The system can quantitatively detect multiple pathogens content, and can achievelevels of LCD display and limit alarm.Main contents and results were as follows:Using network analyzer AD5933chip measuring impedance value of the bacteriumfluid；The hardware circuit of the system was designed. Including impedance measurementmodule, STC89C51microcontroller, resistive voltage conversion module, a voltage signalamplification circuit module, A/D converter module, LCD module, keyboard scanningmodule and alarm circuit module;The software language was programmed using C51language. C51language usingsoftware programs, including the main program, subroutine impedance measurement circuit,A/D conversion subroutine, the subroutine scans the keyboard, LCD display subroutine,alarm subroutine, data processing subroutines;The system was joint debugged and optimized both software and hardware. Use KeiluVision2C51MCU program debugging software program to compile, Proteusmicrocontroller simulation software applications, combined with the resulting hexprocedures, system software and hardware simulation and the FBI, the parameters of thesystem components to improve and optimize the system to get the final design;The mathematical determination model was established. Respectively RLC impedance biosensors and detection precision impedance bridge for Shigella flexneri. Come flexneriShigella bacteria in a concentration range of103~106CFU/mL the "RC"(impedance value-concentration) linear mathematical model, validated by accuracy, indicating that the modelis feasible.After testing the system, the paper design impedance biosensor system to achievepathogen detection, calculation, comparison, display and limit alarm functions, to achievethe desired goals.