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.

Continuous cardiac output is a significant matter that must be considered in monitoring the functioning of cardiovascular system. A non-invasive sensing system that is based on measuring electrical bioimpedance variations of radial artery is proposed to evaluate the physical condition of patient. To optimize the signal acquisition, different electrode placement strategies are compared with the goal of finding the most suitable ones. The finite element method (FEM) simulation of sensitivity distribution and experimental measurements on radial artery are performed for experimenting circular and distal electrode placements. Importantly, also the modified electrode placement strategies, guided by the idea of focused impedance method (FIM), are investigated. To reduce the number of electrodes in measurement setup, its novel version is proposed: a five-electrode FIM strategy. The efficiency of the proposed strategy can be seen in the reduced amount of required number of electrodes: the smaller area of electrode-skin contact interface results in smaller influence of uncertainties. Moreover, the reduced number of electrodes contributes to benefit through developing simpler instrumentation having lower energy consumption and cheaper manufacturing costs. The results show the advances of the proposed novel five-electrode FIM strategy for measuring the pulsating volume of blood in radial artery with the goal of determining the central aortic pressure (CAP) of blood.

Impedance spectroscopy is a common approach in assessing passive electrical properties of biological matter. However, several problems appear in microfluidic devices in connection with the requirement for high sensitivity of signal acquisition from small volume sensors. The developed compact and inexpensive analyzer provides impedance spectroscopy measurement from three sensors, both connected in direct and differential modes. Measurement deficiencies are reduced with a novel design of sensors, measurement method, optimized electronics, signal processing, and mechanical design of the analyzer. Proposed solutions are targeted to the creation of reliable point-of-care (POC) diagnostic and monitoring appliances, including lab-on-a-chip type devices in the next steps of development. The test results show the good working ability of the developed analyzer; however, also limitations and problems that require attention and further improvement are appointed.

Purpose: This paper aims to give a brief overview of dielectric properties, relative complex permittivity and its dependence on frequency. The significance of different approaches to complex permittivity is also discussed. Design/methodology/approach: The different mechanisms of polarization are then presented. Dielectric measurements are given, and an RC parallel-equivalent circuit is used to simulate a parallel plate capacitor, and the way in which the impedance of the circuits is affected by frequency is illustrated in their respective diagrams. The way in which dielectric properties change with time is also discussed. Findings: The goal of this paper is to give an overview of the characteristics of the dielectrics and how frequency affects the relative complex permittivity and to present different approaches to and equations for the relative complex permittivity, such as that of Debye, Cole–Cole, Cole–Davidson and Havriliak–Negami. In addition, three mechanisms of polarization, namely, electronic, atomic and bipolar, are presented. The most common dielectric characterization device, a capacitor with parallel plates between which the dielectric material under study is located, is also discussed. Ohmic and dielectric losses of a non-ideal capacitor are accounted for. Furthermore, this paper studies the equivalent circuits of a non-ideal parallel plate capacitor, those being a resistor and an ideal capacitor connected either in series or in parallel. Originality/value: Finally, dielectric responses to both time and to stepwise excitation are given.

Monitoring of the environment is a global priority due to the close connection between the environmental pollution and human health. Many analytical techniques using various methods have been developed to detect and monitor the levels of pollutants (pesticides, toxins, bacteria, drug residues, etc.) in natural water bodies. The latest trend in modern analysis is to measure pollutants in real-time in the field. For this purpose, biosensors have been employed as cost-effective and fast analytical techniques. Among biosensors, impedance biosensors have significant potential for use as simple and portable devices. These sensors involve application of a small amplitude AC voltage to the sensor electrode and measurement of the in-/out-of-phase current response as a function of frequency integrated with some biorecognition element on the sensing electrodes that can bind to the target, modifying the sensor electrical parameters. However, there are some drawbacks concerning their selectivity, stability, and reproducibility. The aim of this paper is to give a critical overview of literature published during the last decade based on the development issues of impedimetric biosensors and their applicability in water analysis.

Population aging and the consequent increase in chronic patients are driving research and development of multiple biomedical sensor technologies. These allow for better monitoring of people’s health status as well as improved diagnosis, which anticipate a more personalized, preventive, and proactive healthcare. Bioimpedance technology offers valuable information about tissue/cell physiology and pathology. This way bioimpedance sensors technology is becoming the basis of novel and noninvasive medical diagnostic devices.