Bioelectrical Impedance Methods for Noninvasive Health Monitoring: A Review.
17 Jun 2014-Vol. 2014, pp 381251-381251
TL;DR: The working principles, applications, merits, and demerits of these methods has been discussed in detail along with their other technical issues followed by present status and future trends.
Abstract: Under the alternating electrical excitation, biological tissues produce a complex electrical impedance which depends on tissue composition, structures, health status, and applied signal frequency, and hence the bioelectrical impedance methods can be utilized for noninvasive tissue characterization. As the impedance responses of these tissue parameters vary with frequencies of the applied signal, the impedance analysis conducted over a wide frequency band provides more information about the tissue interiors which help us to better understand the biological tissues anatomy, physiology, and pathology. Over past few decades, a number of impedance based noninvasive tissue characterization techniques such as bioelectrical impedance analysis (BIA), electrical impedance spectroscopy (EIS), electrical impedance plethysmography (IPG), impedance cardiography (ICG), and electrical impedance tomography (EIT) have been proposed and a lot of research works have been conducted on these methods for noninvasive tissue characterization and disease diagnosis. In this paper BIA, EIS, IPG, ICG, and EIT techniques and their applications in different fields have been reviewed and technical perspective of these impedance methods has been presented. The working principles, applications, merits, and demerits of these methods has been discussed in detail along with their other technical issues followed by present status and future trends.
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TL;DR: This chapter introduces the finite element method (FEM) as a tool for solution of classical electromagnetic problems and discusses the main points in the application to electromagnetic design, including formulation and implementation.
Abstract: This chapter introduces the finite element method (FEM) as a tool for solution of classical electromagnetic problems. Although we discuss the main points in the application of the finite element method to electromagnetic design, including formulation and implementation, those who seek deeper understanding of the finite element method should consult some of the works listed in the bibliography section.
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TL;DR: A deeper understanding of the fundamental challenges faced for wearable sensors and of the state-of-the-art for wearable sensor technology, the roadmap becomes clearer for creating the next generation of innovations and breakthroughs.
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TL;DR: In this article, an updated review of EIS main implementations and applications is presented, as well as a broad range of applications as a quick and easily automated technique to characterize solid, liquid, semiliquid, organic as well and inorganic materials.
Abstract: . Electrical impedance spectroscopy (EIS), in which a sinusoidal test voltage or current is applied to the sample under test to measure its impedance over a suitable frequency range, is a powerful technique to investigate the electrical properties of a large variety of materials. In practice, the measured impedance spectra, usually fitted with an equivalent electrical model, represent an electrical fingerprint of the sample providing an insight into its properties and behavior. EIS is used in a broad range of applications as a quick and easily automated technique to characterize solid, liquid, semiliquid, organic as well as inorganic materials. This paper presents an updated review of EIS main implementations and applications.
234 citations
Cites background from "Bioelectrical Impedance Methods for..."
...Fat tissues are characterized by low electrical conductivity (i.e., high impedance values) while lean tissues present high electrical conductivity (i.e., low impedance values) due to the high content of electrolytes (Kanti Bera, 2014)....
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TL;DR: The basis and fundamentals of bioimpedance measurements are described covering issues ranging from the hardware diagrams to the configurations and designs of the electrodes and from the mathematical models that describe the frequency behavior of the bioimpingance to the sources of noise and artifacts.
Abstract: This work develops a thorough review of bioimpedance systems for healthcare applications. The basis and fundamentals of bioimpedance measurements are described covering issues ranging from the hardware diagrams to the configurations and designs of the electrodes and from the mathematical models that describe the frequency behavior of the bioimpedance to the sources of noise and artifacts. Bioimpedance applications such as body composition assessment, impedance cardiography (ICG), transthoracic impedance pneumography, electrical impedance tomography (EIT), and skin conductance are described and analyzed. A breakdown of recent advances and future challenges of bioimpedance is also performed, addressing topics such as transducers for biosensors and Lab-on-Chip technology, measurements in implantable systems, characterization of new parameters and substances, and novel bioimpedance applications.
87 citations
References
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TL;DR: Various novel block based time–frequency domain adaptive filter structures for cardiac signal enhancement are presented and the performance of the block based algorithms is superior to the LLMS counterparts in terms of signal to noise ratio improvement (SNRI), excess mean square error (EMSE) and misadjustment (M).
32 citations
TL;DR: In this paper, the authors presented AC impedance measurements (EIS) on a Li-Tec 40 Ah Li-Ion battery cell, including measurements in a climate chamber at different temperatures.
Abstract: This work presents AC impedance measurements (EIS) on a Li-Tec 40 Ah Li-Ion battery cell, including measurements in a climate chamber at different temperatures. The objective of this work is to provide a preliminary basis for estimating the potential of using EIS as a diagnostic tool for battery capacity measurements. In order to estimate the feasibility a Li-Ion battery cell is characterized by several EIS measurement, including measurements in a controlled temperature environment. From the measurements it can be seen that the impedance spectrum indeed changes as a function of State-of-Charge (SOC). However, measurements also show that the same spectrum is also strongly temperature dependent. Is is however concluded that EIS can potentially be used as a capacity diagnostic tool if a non-isothermal battery model based on EIS input data can be developed. The climate chamber measurements also features temperature data of the battery temperature compared to surrounding temperature, this data shows that a battery voltage drop will invoke a battery temperature increase. As the impedance measurements presented in this work are carried out on flexible low-cost Labview platform using conventional data acquisition equipment, suggestions have been presented on how EIS, as a diagnostic tool, preferably can be embedded in the battery management system.
31 citations
TL;DR: Experimental results done on various images clearly indicate that the proposed algorithm improves the quality of the reconstructed images while keeping the computation time significantly lower than other traditional methods.
31 citations
"Bioelectrical Impedance Methods for..." refers methods in this paper
...In some applications the electrical permittivity of the DUT is reconstructed from the voltage current data collected at the boundary and the imaging modality is called electrical capacitance tomography (ECT) [125, 133, 167, 168] which is generally used in industrial process application and mechanical and material engineering....
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...In some applications the electrical permittivity of the DUT is reconstructed from the voltage current data collected at the boundary and the imaging modality is called electrical capacitance tomography (ECT) [125, 133, 167, 168] which is...
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...EIT is a low cost, portable, fast, noninvasive, nonionizing, and radiation free technique, and hence it is found advantageous in several fields of applications application compared to the other computed tomographic methods like X-ray CT [134–136], X-raymammography [137],MRI [138, 139], SPECT [140, 141], PET [142, 143], ultrasound [144, 145], and so forth....
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TL;DR: The EIS method is suggested to characterize the electromechanical property of a conductive fabric in designing a thin and flexible fabric pressure sensor and finds that their electrical impedance spectra depend not only on the electrical properties of the conductive yarns, but also on their weaving structures.
Abstract: When we use a conductive fabric as a pressure sensor, it is necessary to quantitatively understand its electromechanical property related with the applied pressure We investigated electromechanical properties of three different conductive fabrics using the electrical impedance spectroscopy (EIS) We found that their electrical impedance spectra depend not only on the electrical properties of the conductive yarns, but also on their weaving structures When we apply a mechanical tension or compression, there occur structural deformations in the conductive fabrics altering their apparent electrical impedance spectra For a stretchable conductive fabric, the impedance magnitude increased or decreased under tension or compression, respectively For an almost non-stretchable conductive fabric, both tension and compression resulted in decreased impedance values since the applied tension failed to elongate the fabric To measure both tension and compression separately, it is desirable to use a stretchable conductive fabric For any conductive fabric chosen as a pressure-sensing material, its resistivity under no loading conditions must be carefully chosen since it determines a measurable range of the impedance values subject to different amounts of loadings We suggest the EIS method to characterize the electromechanical property of a conductive fabric in designing a thin and flexible fabric pressure sensor
29 citations
"Bioelectrical Impedance Methods for..." refers methods in this paper
...EIS can be potentially used as a nondestructive evaluation technique [55] for a number of applications in the field of science engineering and technology....
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TL;DR: A multi-frequency time-difference EIT (mftdEIT) image reconstruction algorithm based on the concept of the equivalent homogeneous complex conductivity is derived, which would be worthwhile including the effects of three-dimensional current flows inside the human thorax.
Abstract: We evaluated the performance of the lately developed electrical impedance tomography (EIT) system KHU Mark1 through time-difference imaging experiments of canine and human lungs. We derived a multi-frequency time-difference EIT (mftdEIT) image reconstruction algorithm based on the concept of the equivalent homogeneous complex conductivity. Imaging experiments were carried out at three different frequencies of 10, 50 and 100 kHz with three different postures of right lateral, sitting (or prone) and left lateral positions. For three normal canine subjects, we controlled the ventilation using a ventilator at three tidal volumes of 100, 150 and 200 ml. Three human subjects were asked to breath spontaneously at a normal tidal volume. Real- and imaginary-part images of the canine and human lungs were reconstructed at three frequencies and three postures. Images showed different stages of breathing cycles and we could interpret them based on the understanding of the proposed mftdEIT image reconstruction algorithm. Time series of images were further analyzed by using the functional EIT (fEIT) method. Images of human subjects showed the gravity effect on air distribution in two lungs. In the canine subjects, the morphological change seems to dominate the gravity effect. We could also observe that two different types of ventilation should have affected the results. The KHU Mark1 EIT system is expected to provide reliable mftdEIT images of the human lungs. In terms of the image reconstruction algorithm, it would be worthwhile including the effects of three-dimensional current flows inside the human thorax. We suggest clinical trials of the KHU Mark1 for pulmonary applications.
29 citations