Research On Embedded Electrical Impedance Measurement System And Its Application

Impedance measurement technology is an important part of electronic measurement technology.It has the characteristics of non-invasive,simple to use and low complexity.It is widely used in biomedical,electrochemical,industrial control,power grid control and other fields,and it can meet the measurement needs of various parameters.However,common impedance measurement analysis instruments on the market have problems such as large volume,high power consumption and high cost,which increase the difficulty of use,making it difficult to apply to applications such as mobile and outdoor surveillance.Based on this problem,this paper develops a graphical portable impedance measurement system based on S3C6410 processor and AD5933 chip.This paper use the OK6410 development board based on the S3C6410 processor as the control platform and display unit,an impedance acquisition circuit was constructed using the AD5933 chip,and data was exchanged with the controller through the AD5933 IIC bus.The signal conditioning circuit,feedback circuit and other parts were designed to simplify the circuit design,improve the accuracy,save the cost and improve the portability.The Linux system is used as the embedded software platform,and Qt is used to develop the impedance measurement software.The necessary parameters for the AD5933 measurement operation were embedded.The software includes data and acquisition program,data processing program and drawing program.The BootLoader and kernel for the platform were compiled.And a file system containing the AD5933 driver and impedance measurement software was compiled.The start-up file was modified,and each part was programmed into the development board.And the measurement equipment was able to start the measurement program automatically,Impedance measurements can be performed without the help of a desktop computer.Using the system constructed above,impedance measurement tests were performed on R-C circuits,milk,and NaCl solutions.After testing,the impedance average relative error of the system is 0.422%,the signal-to-noise ratio is 64.11dB,and the phase average absolute error is 0.527°.The measurement results were compared with the data obtained by the WK6500B impedance analyzer.The results are highly consistent.Finally,the system and the impedance analyzer measured and compared the impedance data of 79 human blood samples.The results showed that the data of 21 cases were similar.After experiments,the system has good portability and good measurement accuracy,and it is easy to use.And it fully meets the basic impedance measurement requirements.