Design of bioelectrical impedance measurement system based on AD5940 and STM32
Aiming at the problems of complex structure,low integration,and high cost of traditional impedance measurement systems.A portable impedance measurement system with a frequency range of 0.01 Hz to 200 kHz and supporting USB bus is developed.The system adopts the high-precision impedance conversion chip AD5940 as the measurement core and the STM32F411RET6 processor as the control core.AD5940 through the PC configuration parameters can be set up single-frequency and multi-frequency measurement.The impedance data are transmitted to the upper PC for processing through the USB bus,display,and storage.The resistance measurement experiments show that the average relative error of the system is 0.11%,and the SNR is 70.15dB.The R-C three-element impedance model experiment shows that the average absolute error of the system amplitude is 0.64Ω,the phase angle is 0.447°,and the bioelectrical impedance measurement system has good reliability and stability.
bioelectrical impedancemulti-frequency excitationupper PCbioimpedance measurement system
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