Realization and Evaluation of the Device for Measuring the Impedance of Human Body for Detecting the Respiratory and Heart Rate

The idea of a device for measuring the impedance of human body with the target of monitoring the respiratory and heart rate is proposed in this paper. Hardware realization of the proposed idea is described with the illustration of the custom designed printed circuit board. Preparation of electrode shirts with various electrode placement configurations is introduced. Series of experimental measurements in the cases of dynamic bioimpedance reference and single human subject are described and results shown to evaluate the custom made device. The excitation frequencies in the range of 2 MHz– 20 MHz are utilized in the cases of large foil and textile electrodes to focus on the use of the capacitive connection to theobject – constituting the novelty of the current paper. The results are analysed concerning the dependency of the visual availability of the interesting signal of breathing and heart rate of the material and the placement of the electrodes. Availability of breathing is found to be evident in all of the experimented cases. The heart rate is found to be challenging because of the presence of high frequency noise

Principles for the Design of Impedance Spectroscopy Devices for Identification of Dynamic Bio‐Systems. D\ufcnaamiliste bios\ufcsteemide impedantsspektroskoopia seadmete disaini printsiibid

Doctoral thesis 2/2018 Doktorit\uf6\uf6 2/201

Acoustic Forward Model for Guided Wave Propagation and Scattering in a Pipe Bend

The sections of pipe bends are hot spots for wall thinning due to accelerated corrosion by fluid flow. Conventionally, the thickness of a bend wall is evaluated by local point-by-point ultrasonic measurement, which is slow and costly. Guided wave tomography is an attractive method that enables the monitoring of a whole bend area by processing the waves excited and received by transducer arrays. The main challenge associated with the tomography of the bend is the development of an appropriate forward model, which should simply and efficiently handle the wave propagation in a complex bend model. In this study, we developed a two-dimensional (2D) acoustic forward model to replace the complex three-dimensional (3D) bend domain with a rectangular domain that is made artificially anisotropic by using Thomsen parameters. Thomsen parameters allow the consideration of the directional dependence of the velocity of the wave in the model. Good agreement was found between predictions and experiments performed on a 220 mm diameter (d) pipe with 1.5d bend radius, including the wave-field focusing effect and the steering effect of scattered wave-fields from defects

HPLC Analysis of Aliphatic Sulfonate Surfactants using Ion- Pair Detection

Abstract. A method was developed for the analysis of a number of surfactants which contained no UV-chromophores, using RP-HPLC with Indirect Photometric Detection, IPD. Pyridinium salts such as N-methylpyridinium iodide, N-methyl-2,2'-dipyridinium iodide and N,N'-dimethyl-2,2'-dipyridinium diiodide, were used as the visualization reagents, forming ion-pair complexes with the sulfonate surfactants. This allowed ordinary UV-detection. N-methylpyridinium iodide proved to be a suitable reagent, both with respect to ease of preparation and response. The eluents consisted of mixtures of acetonitrile and water, being 0.1- 0.25 mM with respect to pyridinium salt. The method was sensitive and exhibited good signal to noise ratios, as well as linear responses over a wide concentration range. All of the analyzed surfactants were separated, including the diastereomeric forms of some of the surfactants

Precise Eddy Current Impedance Measurement of Metal Plates

Properties of conductive materials can be characterized and validated by electrical conductivity. Eddy current measurements have many benefits as compared to 4-point contact measurements. Combining theoretical and experimental studies have shown that with single planar spiral coil absolute measurements can be carried out with accuracy less than 10%

Methods for Detection of Bioimpedance Variations in Resource Constrained Environments

Changes in a certain parameter are often a few magnitudes smaller than the base value of the parameter, specifying significant requirements for the dynamic range and noise levels of the measurement system. In case of electrical bioimpedance acquisition, the variations can be 1000 times smaller than the entire measured value. Synchronous or lock-in measurement of these variations is discussed in the current paper, and novel measurement solutions are presented. Proposed methods are simple and robust when compared to other applicable solutions. A common feature shared by all members of the group of the proposed solutions is differentiation. It is achieved by calculating the differences between synchronously acquired consecutive samples, with lock-in integration and analog differentiation. All these methods enable inherent separation of variations from the static component of the signal. The variable component of the bioimpedance can, thus, be acquired using the full available dynamic range of the apparatus for its detection. Additive disturbing signals and omnipresent wideband noise are considered and the method for their reduction is proposed

Eddy Current Validation of Euro-Coins

The measurement of electrical conductivity using eddy current (electro magnetic induction) sensors is the most promising solution for validation of metal coins in coin handling devices, as the electrical conductivity is a very distinctive property of specific alloys. Low cost, simple and robust nature, and also possibility for high-speed precise measurements are the advantages of electromagnetic sensors. Multi-frequency scanning the coins under test at various field penetration depths is preferred due to the sophisticated "construction" of various alloys in nowadays coins. Air-core measurement coils have an additional advantage-a possibility to measure absolute values of conductivity without repetitive calibration of sensors and the measurement systems. Development of solutions for eddycurrent validation of metal coins has been investigated together with comparing the experimental results with the values derived from theoretical models. Frequency range of 10 kHz to 10 MHz have been considered (particularly up to 500 kHz for precision measurements) and conductivity values to be measured from 4 to 40% of IACS (International Annealed Copper Standard) conductivity (about 60 MS/m). The results demonstrate that the precise, highspeed, low-cost and robust coin validation system can be developed on the basis of air-core coil arrays

Fiducial Point Estimation Solution for Impedance Cardiography Measurements

International audienceICG (impedance cardiography) is in parallel to ECG (electrocardiography) an important indicator of the functioning of the heart and of the overall cardiovascular system. Adding the ICG to ECG measurement functionality into the wearable devices improves the quality of health monitoring, as the ICG reflects relevant hemodynamic parameters (informative time intervals, but also the stroke volume and cardiac output and their variability). The most challenging task of the ICG signal processing is to extract the key points B, C, X of the cardiac periodstart, peak-location, and value at this point and the end of the LVET (left ventricular ejection time) sub-period in the cardiac cycle. A novel block diagram and analog implementation of it has been proposed, analyzed, and discussed, with discussion of the benefits of the proposed solution. The proposed solution enables developing of relatively simple very power-efficient solutions, monitoring the ICG values of the person with smart and efficient data acquisition and processing