Research And Design Of Digital Blood Lead Analyzer

Lead is one of the heavy metal element which is harmful to human body, according to nervous system, hematopoietic system and the digestive system. The lead poisoning is derived from a variety of sources, including polluted air,water,food,leaded gasoline and so on. Lead poisoning on children’s damage is more serious, especially intelligence development and growth in children.It is accordingly of far reaching importance that making children grow up healthily by popularizing the hospital detection of blood lead. In this thesis, domestic andinternational current situation of the development of blood lead analyzerare described and discussed,theadvantages and disadvantages of determination of lead methods are also analyzed.theelectrochemical assay method we used is square wave stripping voltammetry,and the method is applied to the analysis of actualblood sample trace lead.The three-microelectrode system which is the research focus about electrochemical reaction is used in this thesis.The system provides accurate voltage by High-precision op amp and translates chemical energy to micro current by electrochemical sensors.The subject has designed hardware control system of blood lead analyzer based on LPC2368which used the ARM7as core, including a potentiostat that is composed of DAC and precision operational amplifiers,a low current measuring circuit composed by special sampling method and high-resolution A/D converter,CPU and peripheral circuit,the liner power,communication,printing and others.The analyzer can control and measure signals in an electrochemistry system such as current and potential. Meanwhile, the software control system has been developed by C language with the development environment for the KEIL, including the electrochemical experiments algorithm of three-electrode system, experimental data-processing and communication,menu module,printing and other modules. Beyond that,The subject provides some studies about the interference problem that comes from current signal,and reducing the source noise, circuit board interference and system disturbance, which can significantly improve the accuracy of the instrument.the result was satisfactory.For this characteristic,this thesis has developed a instrument with high precision,it is simple and convenient with high sensitivity and little interference.In the end, the performance of the whole analyzer system is tested through experiment and blood sample. The results show that the blood lead analyzer can meet the design requirements adequately.