Gonzalez-Landaeta Rafael, Casas Oscar, Pallàs-Areny Ramon
Instrumentation, Sensors and Interface Group, Universitat Politècnica de Catalunya, Barcelona, Spain.
IEEE Trans Biomed Eng. 2008 Mar;55(3):1163-7. doi: 10.1109/TBME.2007.906516.
In this paper, a novel technique for heart rate measurement on a standing subject is proposed that relies on electrical impedance variations detected by a plantar interface with booth feet, such as those in some bathroom weighting scales for body composition analysis. Heart-related impedance variations in the legs come from arterial blood circulation and are below 500 mOmega. To detect them, we have implemented a system with a gain in excess of 600, and whose fully differential AC input amplifier has a gain of 4.5 and a common-mode rejection ratio (CMRR) higher than 90 dB at 10 kHz. Differential coherent demodulation based on synchronous sampling yields a signal-to-noise ratio (SNR) of about 54 dB . The system sensitivity is 610 mV/Omega. The technique has been demonstrated on 18 volunteers, whose bioimpedance signal and ECG were simultaneously recorded. A Bland-Altman plot shows a mean bias of -0.2 ms between the RR time intervals obtained from these two signals, which is negligible. The technique is simple and user friendly and does not require any additional sensors or electrodes attached to the body, hence no conductive gel or skin preparation.
本文提出了一种针对站立受试者心率测量的新技术，该技术依赖于通过与双脚的足底界面检测到的电阻抗变化，类似于一些用于身体成分分析的浴室体重秤中的那种界面。腿部与心脏相关的阻抗变化源于动脉血液循环，且低于500毫欧。为了检测这些变化，我们实现了一个增益超过600的系统，其全差分交流输入放大器的增益为4.5，在10千赫时共模抑制比（CMRR）高于90分贝。基于同步采样的差分相干解调产生的信噪比（SNR）约为54分贝。该系统灵敏度为610毫伏/欧。该技术已在18名志愿者身上得到验证，他们的生物阻抗信号和心电图被同时记录。布兰德-奥特曼图显示，从这两个信号获得的RR时间间隔之间的平均偏差为-0.2毫秒，可忽略不计。该技术简单且用户友好，不需要在身体上附加任何额外的传感器或电极，因此无需导电凝胶或皮肤准备。
