数字式生物电阻抗与电阻抗断层成像测量系统

A Digital System for Bioimpedance and Electrical Impedance Tomography Measurement System

构建了以ATmega16单片机为控制核心,8个AD5933为数字电极,nRF24L01为无线通信模块的数字式生物电阻抗与电阻抗断层成像（EIT）测量系统。详细阐述了系统结构、电路设计、系统测试、动物组织阻抗测量及EIT成像。经测试,系统相对测量误差可达0.42%,信噪比达76.3dB。该系统不仅可采用二电极法在1~100kHz范围内进行扫频式阻抗测量,而且能实现EIT成像。对SD幼鼠解剖后的组织进行阻抗测量,测量结果显示,数据有效,经最小二乘法拟合,符合Cole-Cole理论,验证了该系统阻抗测量的可行性与有效性;通过盐水槽实验,对场域中物体的分布图像进行重构,重建图像与实际分布吻合,成像效果良好。该系统很大程度上提高了前端测量信号的有效性以及系统的稳定性。

A digital system for bioimpedance and electrical impedance tomography（EIT）measurement controlled by an ATmega16 microcontroller was constructed in our laboratory.There are eight digital electrodes using AD5933 to measure the impedance of the targets,and the data is transmitted to the computer wirelessly through nRF24L01.The structure of the system,circuit design,system testing,vitro measurements of animals＇ tissues and electrical impedance tomography are introduced specifically in this paper.The experimental results showed that the system relative error was 0.42%,and the signal noise ratio was 76.3dB.The system not only can be used to measure the impedance by any two electrodes within the frequency of 1-100 kHz in a sweep scanning,but also can reconstruct the images of EIT.The animal experiments showed that the data was valid and plots were fitting with Cole-Cole theory.The testing verified the feasibility and effectiveness of the system.The images reconstructed of a salt-water tank are satisfactory and match with the actual distribution of the tank.The system improves the effectiveness of the frontend measuring signal and the stability of the system greatly.