Micro Current Measurement Instrument Development And Application

With the continuous development of science and technology and update about thedetection of weak current technology is becoming more and more urgent, the testtechnique in electrochemical and biological, medical, aerospace and other fields havea wide range of applications, plays an important role to promote the development ofrelated fields, micro electric current through the analysis of the test can be found andexplore new natural law, has important practical significance, is also the future pathof the development of science and technology.The micro current measurement technology at home and abroad have certaindevelopment, but most of the equipment circuit structure complex, expensive, bulky,accuracy is not high and there is no display. Therefore, in this paper, the research anddevelopment by using the ADI company new high-performance ADuC84724bit dataacquisition and processing system as the control core of the micro electric currentdetector device.First of all, on the basis of consulting a large number of documents, weak currentdetection theory research at home and abroad are introduced and the development of ameasuring instrument, developed new type of weak current meter device system, andthe main work accomplished in this paper.Secondly, introduced and compared several methods of the weak currentmeasurement, including high impedance is negative feedback shipment fly solution,switch, operational amplifier, capacitor integral method I-F switch in the I-V method,the operational difference circuit transformation method, analyzes the advantages anddisadvantages of various methods, the simulation and experimental comparison,selection in the design can better suppress common mode interference and zero driftof the op-amp difference circuit I-V transformation method.And then,micro current measurement system is introduced in detail, and the basicprinciple and hardware structure. Hardware part includes microcomputer controlcircuit, differential measurement amplifier circuit, filter circuit, power circuit,communication circuit, LCD circuit, main link. Micro current signal amplification, ismainly introduced the design of the automatic shift and butterworth filter design.Carefully elaborated the micro current measurement instrument based on controlchip ADuC847software design, including various functions subprogram (initialization program shift gear, relay, LCD procedures, data collection procedures,etc.) in the writing principle and flow chart, and then introduced the PC softwaredevelopment environment, the user oriented application software interface andoperation way.Finally in micro current measurement instrument is introduced, the debuggingprocess need to be aware of some matters, micro current measurement experiment anddebugging results of the process and problem analysis, and application inelectrochemical analysis.