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Journal ArticleDOI

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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Citations
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Book ChapterDOI
01 Jan 1997
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.

1,820 citations

Journal ArticleDOI
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.
Abstract: Wearable sensors have recently seen a large increase in both research and commercialization. However, success in wearable sensors has been a mix of both progress and setbacks. Most of commercial progress has been in smart adaptation of existing mechanical, electrical and optical methods of measuring the body. This adaptation has involved innovations in how to miniaturize sensing technologies, how to make them conformal and flexible, and in the development of companion software that increases the value of the measured data. However, chemical sensing modalities have experienced greater challenges in commercial adoption, especially for non-invasive chemical sensors. There have also been significant challenges in making significant fundamental improvements to existing mechanical, electrical, and optical sensing modalities, especially in improving their specificity of detection. Many of these challenges can be understood by appreciating the body's surface (skin) as more of an information barrier than as an information source. With 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.

680 citations

Journal ArticleDOI
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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Journal ArticleDOI
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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Journal ArticleDOI
24 Mar 2013
TL;DR: An anatomically realistic forward solver for thoracic EIT that was built based on high resolution MR image data of a representative adult is presented, demonstrating the ability of the presented forward Solver in generating high-fidelity surface thoraci impedance data for thorACic E IT algorithm development and evaluation.
Abstract: Electrical impedance tomography (EIT) has the potential to provide a low cost and safe imaging modality for clinically monitoring patients being treated with mechanical ventilation. Variations in reconstruction algorithms at different clinical settings, however, make interpretation of regional ventilation across institutions difficult, presenting the need for a unified algorithm for thoracic EIT reconstruction. Development of such a consensual reconstruction algorithm necessitates a forward model capable of predicting surface impedance measurements as well as electric fields in the interior of the modeled thoracic volume. In this paper, we present an anatomically realistic forward solver for thoracic EIT that was built based on high resolution MR image data of a representative adult. Accuracy assessment of the developed forward solver in predicting surface impedance measurements by comparing the predicted and observed impedance measurements shows that the relative error is within the order of 5%, demonstrating the ability of the presented forward solver in generating high-fidelity surface thoracic impedance data for thoracic EIT algorithm development and evaluation.

6 citations

01 Jan 2012
TL;DR: In this paper, a fully parallel multi-frequency electrical impedance tomography (EIT) system called the KHU Mark2.5 is proposed. But the performance of the system is limited.
Abstract: An electrical impedance tomography (EIT) system can visualize conductivity and permittivity distributions inside the human body from measured boundary voltages induced by externally injected currents. We have developed a fully parallel multi-frequency EIT system called the KHU Mark2.5. It is based on an impedance measurement module (IMM) comprising a current source, a voltmeter and a calibration circuit. Each IMM is independent and can calibrate its own current source and voltmeter through an automatic self-calibration procedure. We found that the output impedance values of all current sources are greater than 1M› at the chosen frequencies. The CMRR is around 96dB and the voltmeter SNR is between 80 and 85dB depending. To increase spatial resolution of conductivity and permittivity images, we can cascade multiple EIT systems to form a system with a larger number of channels. They are synchronized by clock synchronization circuits. Physiological events such as cardiac and respiratory functions alter electrical tissue properties. To correlate such events with EIT images, we can perform a biosignal-gated EIT imaging. We can improve interpretation of EIT images by incorporating real-time ECG and respiration signals into EIT images. This may allow us to separate fast cardiac events and slow respiratory events from reconstructed EIT images and also improve the SNR by signal-gated data averaging We present the performance of the KHU Mark2.5 system with experimental results of animal.

6 citations

Journal Article
TL;DR: How to take good ultrasonic pictures of the breast and make correct diagnosis are discussed and diagnostic criteria preliminarily adopted by the Japan Society of Ultrasonics in Medicine are proposed.
Abstract: In this paper, first, how to take good ultrasonic pictures of the breast and make correct diagnosis are discussed. The author stressed the earnest attitude to understand and master the apparatus and correlate ultrasonic pictures with cut surfaces or microscopical figures of the specimen. Secondly, diagnostic criteria preliminarily adopted by the Japan Society of Ultrasonics in Medicine are proposed and are explained practically. The elements of this criteria are shape, border, boundary echoes, internal echoes, posterior echoes, bilateral shadows, changes at surrounding tissues and longitudinal-transverse ratio. Lastly, pictures of the benign and malignant lesions of the breast are shown using typical examples.

5 citations

Book ChapterDOI
03 Feb 2014

5 citations