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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。
The digital bioelectrical impedance and electrical impedance tomography (EIT) measurement system with ATmega16 microcontroller as control core, 8 AD5933 as digital electrode and nRF24L01 as wireless communication module are constructed. Detailed description of the system structure, circuit design, system testing, animal tissue impedance measurement and EIT imaging. After testing, the relative error of the system measurement up to 0.42%, signal to noise ratio of 76.3dB. The system can not only use the two-electrode method in the range of 1 ~ 100kHz sweep impedance measurement, but also to achieve EIT imaging. The impedance measurement of the tissue of SD young rats was carried out. The measurement results showed that the data were valid and fitted by the least squares method, which accorded with the theory of Cole-Cole, which verified the feasibility and validity of impedance measurement. Reconstructing the distribution images of the objects in the field, the reconstructed images are in good agreement with the actual distribution and the imaging effect is good. The system greatly improves the effectiveness of front-end measurement signals and system stability.