ABSTRACT
Objective:To analyze the relationship between the concentration of glucose and the impedance of human blood, and study the relationship between human blood glucose detection and human blood impedance.Methods:The system adopts the AD5933 digital frequency synthesizer (DDS) in the excitation signal is produced, imposed on the impedance under test, the ADC acquisition signal and sent to the corresponding chip DFT digital processing module, measurement results through the I2C sent to the microcontroller, again by the single-chip microcomputer and PC computer communication, the computer shows that the impedance values. Results:The instrument can realize the resistor, capacitor, inductance, glucose solution impedance measuring rapidly and accurately, through experimental verify that resistive impedance deviation from the mean is 0.04, phase deviation from the mean is 0.15°.Conclusion:The glucose concentration of aqueous solution was linearly correlated with the impedance, the correlation coefficient greater than 0.99.
ABSTRACT
Objective To develop and test a high precision medical device which allows measurement of bioimpedance in regions below skin surface,and to enable the assessment of strained muscle's situation and instruct patient's rehabilitation exercise.Methods The system was based on the four-electrode impedance measurement mode and designed by using impedance converter network analyzer AD5933 and monolithic operational amplifier AD844.The hardware consisted of an excitation current source,a response signal adjustment circuit,a digital demodulation circuit and a shield driving circuit.This hardware circuit was combined with a LCD screen and a keyboard,which turned it into a portable precision bioimpedance testing device.Results Using an model of three components as test target,a comparison between the device and the Agilent 4294A precision impedance analyzer was presented.In the range of 1 kHz to 100 kHz,the device showed the similar relative error of the complex impedance's modulus and 1 degree absolute error of the complex impedance's phase.The strained muscle's bioelectrical impedance changes in a clinical case during the convalescent were presented and discussed with the results proven to be clinical meaningful.Conclusions The device is accurate,simple and convenient,which is proved qualified on helping doctors to assess the injury states of the strained muscle and to instruct patient's rehabilitation exercise.