Design of a wideband excitation source for fast bioimpedance spectroscopy
Design of a wideband excitation source for fast bioimpedance spectroscopy
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快速生物阻抗谱宽带激发源的设计
DOI：
10.1088/0957-0233/22/1/013001
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发表时间：
2011-01-01
影响因子：
2.4
通讯作者：
Gao, Zonghai
中科院分区：
文献类型：
--
作者：
Yang, Yuxiang;Kang, Minhang;Gao, Zonghai
与传统的单频一次（OFOT）测量技术相比，多频一次（MFOT）测量生物阻抗谱（BIS）可以大大缩短测量时间，更好地掌握生物体的瞬态生理状态，而多频混合的宽带激励源是MFOT测量BIS的关键部分。本文介绍了一种宽带激励源的设计。首先，基于沃尔什函数合成了一个含有7次谐波的多频混频信号，该信号是一个周期性的矩形信号，其68.9%的能量均匀分布在其7个2n次谐波上。然后利用现场可编程门阵列（FPGA）产生MFM信号，并设计了单极性到双极性转换器（UBC）将单极性信号转换为双极性信号。最后，双极性MFM信号由压控电流源（VCCS）驱动。采用2 R-1C串联模型作为VCCS的负载，并在理论分析的基础上仿真得到了负载上的电压响应。实验结果表明，负载上的实际波形与理论分析吻合较好，表明VCCS对MFM信号具有良好的性能。宽带激励源的设计为BIS的快速测量奠定了良好的基础。
Multi-frequency-one-time (MFOT) measurement of bioimpedance spectroscopy (BIS) can greatly reduce measurement time and grasp the transient physiological status of a living body compared with the traditional one-frequency-one-time (OFOT) measurement technology, and a wideband excitation source mixed with multiple frequencies is a crucial part of MFOT measurement of BIS. This communication describes a design of a wideband excitation source. Firstly, a multi-frequency mixed (MFM) signal containing seven primary harmonics is synthesized based on Walsh functions, which is a periodical and rectangular signal and whose 68.9% of the energy is homogeneously distributed on its seven 2nth primary harmonics. Then the MFM signal is generated by a field programmable gate array (FPGA), and a unipolar-to-bipolar convertor (UBC) is designed to convert the unipolar signal into bipolar signal. Finally, the bipolar MFM signal is driven by a voltage-controlled current source (VCCS). A 2R-1C series model is adopted as the load of the VCCS, and the simulated voltage response on the load is obtained based on the theoretical analysis. Experiments show that the practical waveform on the load matches well with the theoretical analysis, which indicates that the VCCS has a good performance on the MFM signal. The design of the wideband excitation source establishes a good foundation for fast measurement of BIS.