摘要
生物电阻抗的测量是阻抗血流图或电阻抗断层成像的基础。目前的生物电阻抗测量是在安全的交流信号激励下 ,对被测目标的响应信号进行幅值或 和相位的解调得到。常用的硬件解调技术有整流滤波器、开关解调器和模拟乘法器等 ,这些解调器的输出级均需低通滤波器 ,以滤除输出信号中的激励频率或其倍频信号。低通滤波器的使用降低了测量系统的动态特性 ,不适于高速及多通道测量。为此 ,我们设计并实现了一种新的基于采样保持器的高速解调技术 ,该技术不需要低通滤波器 ,在一个信号周期中即可解调出阻抗信息 ,具有高速和相敏解调的特点 。
The bio electrical impedance measurement is the basis of the impedance plethysmography or electrical impedance tomography(EIT). In order to measure the bio electrical impedance, a safe AC stimulus signal is applied to the measured object, and the amplitude or/and phase of the response signal to the stimulus must be demodulated. The common used hardware demodulation techniques are Rectifiers, Switching demodulators, and Multipliers. All of them need a low pass filter(LPF) so that the stimulus frequency or its twice frequency signals can be filtered out. The LPF may worsen the dynamic response of the bio impedance measurement system, and the above demodulation techniques are not suitable for the high speed and multi channel measurements. So a new high speed demodulation method based on Sample and Hold (S/H) techniques was designed, the LPF is not needed in this method. It can demodulate the impedance information in a single signal cycle and has the features of high speed and phase sensitive demodulation. The technique greatly improves the dynamic response of the measurement system.
出处
《北京生物医学工程》
2004年第1期21-23,16,共4页
Beijing Biomedical Engineering
基金
第四军医大学创新工程课题 (CX0 1A0 0 8)
全军医药卫生青年基金课题 ( 0 1Q116)
