Bioimpedance Measurement System Based On FPGA And Electrical Impedance Image Reconstruction Of Cell Model

The dielectric properties of biological tissue is an inherent property of organism,which refers to the electrical response of biological tissues or organs in time-varying electromagnetic fields.The two electrical parameters most concerned by researchers are conductivity and permittivity,which respectively represent the electric and dielectric capacities of tissues or organs.Bioimpedance measuring technology is a non-invasive detecting technique based on the dielectric properties of biological tissue.The basic measurement method is to apply a safe excitation current to the detection object through the body surface electrode,and use the body surface electrode to detect the voltage change of the response.And this technology has extensive application perspective.In order to obtain more impedance information at different frequencies simultaneously,this paper designed a multi-mode excitation bioimpedance measurement system based on FPGA,which overcome the shortcomings of traditional impedance analysers,such as single frequency and voltage/current excitation.Based on the dielectric properties of biological tissues and the dispersion theory of biological cells,a normal/abnormal cell model was constructed.The main work of the paper is as follows:(1)The hardware circuit of the multi-mode impedance measurement system was designed.The hardware circuit was composed of FPGA core circuit,power supply circuit,output channel circuit,forward channel circuit and communication and man-machine interaction interface circuit.(2)Based on the hardware circuit and Verilog HDL,and using Quartus II and ModelSim software,the digital circuit of the multi-mode impedance measurement system was designed in accordance with "top-down,bottom-up" protocol and the design process of the underlying module.The digital circuit system was composed of several bottom functional modules simulated by writing Testbench.(3)The tests were carried out including power supplies,crystal oscillator and the performances of the system.The bottom function modules verified by simulation are converted into configuration files and downloaded to FPGA.(4)The COMSOL and Matlab co-simulation platform are studied,and a frequency domain simulation imaging experiments based on normal and abnormal cell model were designed.