Thomas Johann Seebeck Department of Electronics, Tallinn University of Technology, 12616 Tallinn, Estonia.
Sensors (Basel). 2020 Mar 2;20(5):1363. doi: 10.3390/s20051363.
Changes in a certain parameter are often a few magnitudes smaller than the base value of the parameter, specifying significant requirements for the dynamic range and noise levels of the measurement system. In case of electrical bioimpedance acquisition, the variations can be 1000 times smaller than the entire measured value. Synchronous or lock-in measurement of these variations is discussed in the current paper, and novel measurement solutions are presented. Proposed methods are simple and robust when compared to other applicable solutions. A common feature shared by all members of the group of the proposed solutions is differentiation. It is achieved by calculating the differences between synchronously acquired consecutive samples, with lock-in integration and analog differentiation. All these methods enable inherent separation of variations from the static component of the signal. The variable component of the bioimpedance can, thus, be acquired using the full available dynamic range of the apparatus for its detection. Additive disturbing signals and omnipresent wideband noise are considered and the method for their reduction is proposed.
某些参数的变化往往比参数的基准值小几个数量级，这对测量系统的动态范围和噪声水平提出了重大要求。在电生物阻抗采集的情况下，变化可能比整个测量值小 1000 倍。本文讨论了这些变化的同步或锁定测量，并提出了新的测量解决方案。与其他适用的解决方案相比，所提出的方法简单且稳健。所提出解决方案组的所有成员共有的一个共同特征是微分。它通过计算同步采集的连续样本之间的差异来实现，具有锁定积分和模拟微分。所有这些方法都能够实现固有变化与信号静态分量的分离。因此，可以使用仪器的全部可用动态范围来检测生物阻抗的可变分量。考虑到附加的干扰信号和无处不在的宽带噪声，并提出了减少它们的方法。
