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.

The monitoring of hemodynamic parameters, such as heart rate and blood pressure, provides valuable indications of overall cardiovascular health. It is preferable that such monitoring is non-invasive and in real time via an affordable, compact and small-scale device for maximum convenience. Numerous literature sources have exploited derivations of these parameters from photoplethysmogram (PPG) and electrical bioimpedance (EBI) signal measurements through the use of calculation algorithms of varying complexity. Compared to electrocardiogram (ECG), these measurement techniques have a merit of well-established practices of designing a wearable device that could conveniently be put on a wrist. The current paper provides a comprehensive review on the use of PPG and EBI measurement techniques in the context of hemodynamic parameter monitoring using a wearable device. A special emphasis is placed on the most basic hemodynamic parameter—heart rate—describing different algorithms of heart rate detection and monitoring. The last section provides an overview of commercially available and in-home wearable device technologies based on PPG and EBI measurements, their design challenges, and future prospects.

The utilization of technique for monitoring pulse wave from wrist by using the electrical bioimpedance has been implemented in this paper. A four electrode printed circuit board was used to evaluate the influence of positioning of the electrodes, pressure on the electrodes and individual differences of several volunteers on the availability of pulse wave from wrist. The influence of positioning of the electrode relative to radial artery was verified experimentally, allowing 5 mm shift in both transverse directions. The increasing pressure on the electrode was found to give rise to the time varying change of impedance, caused by pulse wave. This result was confirmed in the case of measurements on several volunteers, proposing the convergence in time varying change of impedance above the pressure of 400 g.

In this paper the determination of the positions of surface plate electrodes on human trunk for measuring the breathing and heart rate by using the electrical bioimpedance is presented. The designed and implemented measurement device - electrode shirt - is described. The novelty of current work is incorporated into the solution of placing the large surface plate electrodes into the garment. Focus is set on the capacitive connection to the object, revealing the problems of the influence of motions and displacement of the electrodes to the result. The best configurations for heart rate are showing the portion of change of the real part of total body impedance up to 5 percent. The result concerning the breathing rate is showing promising results, reaching up to 90 percent of real part of total body impedance. The best determined electrode placement configurations are showing the possibility of detecting the breathing and heart rate by using single electrode placement.

Background: Wearable technologies for monitoring cardiovascular parameters, including electrocardiography (ECG) and impedance cardiography (ICG), propose a challenging research subject. The expectancy for wearable devices to be unobtrusive and miniaturized sets a goal to develop smarter devices and better methods for signal acquisition, processing, and decision-making. Methods: In this work, non-standard electrode placement configurations (EPC) on the thoracic area and single arm were experimented for ECG signal acquisition. The locations were selected for joint acquisition of ECG and ICG, targeted to suitability for integrating into wearable devices. The methodology for comparing the detected signals of ECG was developed, presented, and applied to determine the R, S, and T waves and RR interval. An algorithm was proposed to distinguish the R waves in the case of large T waves. Results: Results show the feasibility of using non-standard EPCs, manifesting in recognizable signal waveforms with reasonable quality for post-processing. A considerably lower median sensitivity of R wave was verified (27.3%) compared with T wave (49%) and S wave (44.9%) throughout the used data. The proposed algorithm for distinguishing R wave from large T wave shows satisfactory results. Conclusions: The most suitable non-standard locations for ECG monitoring in conjunction with ICG were determined and proposed.

Background: Pelotherapy is the traditional procedure of applying curative muds on the skin’s surface—shown to have a positive effect on the human body and cure illnesses. The effect of pelotherapy is complex, functioning through several mechanisms, and depends on the skin’s functional condition. The current research objective was to develop a methodology and electrodes to assess the passage of the chemical and biologically active compounds of curative mud through human skin by performing electrical bioimpedance (EBI) analysis. Methods: The methodology included local area mud pack and simultaneous tap water compress application on the forearms with the comparison to the measurements of the dry skin. A custom-designed small-area gold-plated electrode on a rigid printed circuit board, in a tetrapolar configuration, was designed. A pilot study experiment with ten volunteers was performed. Results: Our results indicated the presence of an effect of pelotherapy, manifested by the varying electrical properties of the skin. Distinguishable difference in the measured real part of impedance (R) emerged, showing a very strong correlation between the dry and tap-water-treated skin (r = 0.941), while a poor correlation between the dry and mud-pack-treated skin (r = 0.166) appeared. The findings emerged exclusively in the frequency interval of 10 kHz …1 MHz and only for R. Conclusions: EBI provides a promising tool for monitoring the variations in the electrical properties of the skin, including the skin barrier. We foresee developing smart devices for promoting the exploitation of spa therapies.