Comparative Study of Measurement Methods for Embedded Bioimpedance Spectroscopy Systems

Abstract

Bioimpedance spectroscopy (BIS) is an advanced measurement method for providing information on impedance changes at several frequencies by injecting a low current into a device under test and analyzing the response voltage. Several methods have been elaborated for BIS measurement, calculating impedance with a gain phase detector (GPD), IQ demodulation, and fast Fourier transform (FFT). Although the measurement method has a big influence on the measurement system performance, a systematical comparative study has not been performed yet. In this paper, we compare them based on simulations and experimental studies. To maintain similar conditions in the implementation of all methods, we use the same signal generator followed by a voltage-controlled current source (VCCS) as a signal generator. For performance analysis, three DUTs have been designed to imitate the typical behavior of biological tissues. A laboratory impedance analyzer is used as a reference. The comparison addresses magnitude measurement accuracy, phase measurement accuracy, signal processing, hardware complexity, and power consumption. The result shows that the FFT-based system excels with high accuracy for amplitude and phase measurement while providing the lowest hardware complexity, and power consumption, but it needs a much higher software complexity.

Wearable and Noninvasive Device for Integral Congestive Heart Failure Management in the IoMT Paradigm

“…Polar demodulation is a promising alternative which asynchronously measures the magnitude and phase of the bioimpedance [ 29 , 30 , 31 , 32 , 33 , 34 ], as shown in Figure 4 . It is a tetra-polar measurement technique based on determining the magnitude and the phase of a complex impedance, Z X , by extracting and processing two voltage signals, V AZ and V AS , obtained as a response to a sinusoidal excitation current, I ex .…”

“…In particular, a gain-phase detector AD8302 from Analog Devices was used. Since the AD8302 chip is intended for communication applications up to 2.7 GHz, a large power consumption is required [ 29 , 30 ]. A custom integrated circuit (IC) architecture that relies on a self-mixing full-wave rectifier was proposed in [ 31 ].…”

“…A custom integrated circuit (IC) architecture that relies on a self-mixing full-wave rectifier was proposed in [ 31 ]. This solution eliminates IA offset errors not addressed in [ 29 , 30 ]. Two adaptive self-sampling schemes are proposed in [ 32 ].…”

Sensors, Circuits, and Systems for Biomedical Applications

“…A number of investigations are currently underway to overcome the issues associated with measuring signals from the human body and existing signal measurement methods. In this Special Issue, four articles focus on this issue [ 5 , 6 , 7 , 8 ]. Ben Atitallah B. et al present a systematic comparison of methods for bioimpedance spectroscopy (BIS) measurement, including the use of a gain phase detector (GPD), IQ demodulation, and fast Fourier transform (FFT), with a focus on magnitude and phase measurement accuracy, signal processing, hardware and software complexity, and power consumption [ 5 ].…”

“…In this Special Issue, four articles focus on this issue [ 5 , 6 , 7 , 8 ]. Ben Atitallah B. et al present a systematic comparison of methods for bioimpedance spectroscopy (BIS) measurement, including the use of a gain phase detector (GPD), IQ demodulation, and fast Fourier transform (FFT), with a focus on magnitude and phase measurement accuracy, signal processing, hardware and software complexity, and power consumption [ 5 ]. The results demonstrate that the FFT-based method achieves high accuracy for amplitude and phase measurement, with low hardware complexity and power consumption but at the cost of higher software complexity.…”