Dudykevych T, Gersing E, Thiel F, Hellige G
Department of Anaesthesiological Research, Centre of Anaesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Germany.
Physiol Meas. 2001 Feb;22(1):19-24. doi: 10.1088/0967-3334/22/1/303.
In this paper we present the concept, the design and the test procedure for a DSP-based high-precision and high-performance wide-band (up to 10 MHz) bioimpedance analyser module for application in EIT or bioimpedance spectroscopy. The module implements a digital concept with appropriate signal conditioning hardware for voltage and current measurement, early signal digitization and subsequent digital signal processing in order to calculate the components of impedance (or admittance). At low frequencies, the module utilizes the conventional direct conversion method, whereas at high frequencies the undersampling technique is used. The advantages of the described system are the following: (a) the frequency range is extended to higher frequencies, (b) the number of data sampled per time interval is significantly reduced, and (c) the current consumption and the costs of the ADCs can be significantly reduced. The validation procedure is performed by comparing the measured and theoretical values of the magnitude and the phase of the impedance for a commonly used tissue model. The module offers an accuracy of better than 0.012% for the magnitude of impedance and better than 0.02 degrees for the phase.
在本文中，我们介绍了一种基于数字信号处理器（DSP）的高精度、高性能宽带（高达10MHz）生物阻抗分析仪模块的概念、设计和测试程序，该模块用于电阻抗断层成像（EIT）或生物阻抗谱。该模块采用数字概念，配备适用于电压和电流测量的信号调理硬件、早期信号数字化以及后续数字信号处理，以计算阻抗（或导纳）的分量。在低频时，该模块采用传统的直接转换方法，而在高频时则使用欠采样技术。所述系统的优点如下：（a）频率范围扩展到更高频率；（b）每个时间间隔采样的数据数量显著减少；（c）电流消耗和模数转换器（ADC）的成本可显著降低。通过比较常用组织模型的阻抗幅值和相位的测量值与理论值来执行验证程序。该模块的阻抗幅值精度优于0.012%，相位精度优于0.02度。
