频域提取法提高动态阻抗谱测量精度

Precision Improvement of Dynamic Pulse Impedance Spectrum by Over Sampling and FFT

血液成分的无创检测对于糖尿病等疾病的诊断和治疗具有重要意义．在血液成分无创检测领域,阻抗谱法血液成分无创检测技术具有重要应用价值．但血液成分复杂,并且各成分浓度变化对血液的阻抗特性影响较小．为了实现基于生物电阻抗的血液成分分析必须提高阻抗测量精度．以动态脉搏波阻抗谱原理为依据,并结合过采样技术,研究了动态阻抗谱的频域提取方法．用FFT频域提取基波分量代替幅值,克服了时域峰峰值提取的困难,同时采用过采样技术,可以实现过采样频率每提高一倍,信噪比提高3dB．实验结果表明,这两种方法结合可以显著提高动态阻抗谱测量精度．

Noninvasive measurement of blood components is of great value to the diagnosis and treatment. The concrete relation between blood electrical properties and its components enables the noninvasive measurement of blood components by impedance spectrum. The difficulty is that blood is such a complicated fluid that its impedance variance by the concentration difference of any component is rather tiny. In order to analyze blood components by bio-impedance technology, it is necessary to obtain blood bio-impedance spectrum of high accuracy. In this paper, the method of dynamic impedance spectrum in frequency domain based on the principle of dynamic pulse impedance spectroscopy combined with the technology of over sampling is analyzed. The amplitude of pulse wave impedance replaced peak-to-peak value of impedan by its principal components calculated from FFF, the difficulty to compute ce wave in time domain is overcome. And the SNR is increased by 3 dB when the sampling frequency doubled. Results show that the method mentioned above greatly improve the accuracy of dynamic impedance spectrum.