The Research And Design Of Human Body Composition Analyzer Based On The Theory Of Electrical Bio-Impedance

Electrical bio-impedance measurement technology is a detecting technique that uses certain means to extract the bio-impedance information to reflect the biomedical information of physiology and pathology. Human body composition analysis is an important application branch of electrical bio-impedance measurement technology. It can get the parameters of the human body composition by measuring the impedance. Recent decades, human body composition analysis has rapid developed in academic research and business because of the advantages, such as simple, accurate, noninvasive, safe, low cost, wide application and so on. This paper designs a body composition analyzer, and the main work of this paper mainly embodies on the following aspects:① This paper decides the analysis method of the body composition analyzer. From the electrical impedance principle, it indicates the theory of the analysis method. The basic calculation formula of the analysis method is also determined. And in actual use, the coefficient of the formula has carried on the preliminary calibration.② This paper designs the whole hardware structure of the human body composition analyzer at the requirements of low cost and high precision. In order to realize the requirement of measuring body weight, weight measurement circuit is achieved. The effective electrode structure that greatly reduces the impedance of the electrode and skin is also realized. And this paper devises a proper switching circuit to adjust the electrode conduction sequence. Not only the stable voltage acquisition circuit and current acquisition circuit that achieve the impedance calculation method of DPSD is designed, but also the power circuit, communication circuit and controller is accomplished.③ Aiming to realize the system function of the body composition analyzer, the software of the whole system has carried on the establishment and implementation. This paper fulfills the body composition analysis application software used by VC language to implement the function of upper system, because the upper system is the most important part of the whole system. At the same time, the single chip microcomputer and FPGA are programed and debugged. So the whole software function is completed.④ In order to understand the detection performance of the system, the output impedance of constant current source, the SNR of impedance measurement circuit, the resistance measurement precision and frequency response are all done the test experiment. Test results show that human body composition analyzer hardware system has high performance and it can satisfy the measurement requirement of body composition analysis.