Electrical impedance testing

Eddy-Current Methods This is one of the earliest NDT methods and is still used Basically, this method reveals any differences tn electrical impedance between parts to be tested and a reference sample. Parts to be examined are passed through a coil or explored with a probe, and a trace appears on a CRT, Since magnetic and electrical characteristics are closely related to metallurgical quantities, a trace position or pattern or a meter reading clearly shows variations in metal hardness and composition, as well as defects. Both ferrous and nonferrous parts can be tested, and various coils, probes, and detector lips are available,... 

On the other hand, electrical impedance measurement of bacterial suspensions (.Listeria innocua) was carried out on a Si-glass chip. This method was used to perform a cell viability test. This is because the metabolic products produced from viable cells modify the ionic strength of a low-conductivity medium, significantly altering its electrical characteristics. Later work also involved the detection of the presence of small numbers of bacterial cells in a Si chip 100 L. innocua cells, 200 L. monocytogenes cells, and 40 E. coli cells [93,885], In another report, impedance spectroscopy has been used for analysis of erythrocytes in a glass-polyimide chip [886]. 

The usability for this model in FDM was tested with a 2D version of the same model in previous article [12]. The similarity of the arterial network structure to actual arterial networks have been estimated by the creators of the CCO algorithm [5], but its apphcability in final electric impedance simulation is yet to be tested. At the moment the model is not incorporated into a dynamic chest or full body model. The authors are investigating possibilities to add the features of this dynamic model into existing full body dynamic anatomy models for sophisticated and user-friendly modeling methods. 

Figure 2. Bio-electronic measurement system (a) Electrical model [6], [7] of an electrode, (b) Electrical model of an electrode partially covered by cells (ff). (c) Circuit for cell-electrode impedance testing. Values for a 50 X 50 om electrode size are R =5 A kfl, Z(co)=Cj R, with = 0.37 nE and R = 25 Mf2.

When measuring electrical impedance, the main specifications are frequency and impedance measurement ranges, precision, speed, and points per sweep. Just as important are requirements of the test setup like two-, three-, or four-electrode configuration, bias control and scalability—when it comes to multichannel or high... 

The electrical impedance, conductivity, real and imaginary part of dielectric permittivity and magnetic permeability have been determined using an Agilent E4991A RF Spectrum Analyzer. The used frequency was in the range from 1 MHz to 3 GHz. The sample thickness varied from 0.5 to 1 mm. The frequency step was 20 Hz. The tests were performed at room temperature (=25°C)... 

The current interrupt test is particularly easy to perform with single cells and small fuel cell stacks. With larger cells the switching of the higher currents can be problematic. Current interrupts and electrical impedance spectroscopy give us two powerful methods of finding the causes of fuel cell irreversibihties, and both methods are widely used. 

Sim M. H., et al. (2013) Development and Evaluation of an Improved Technique for Pulmonary Function Testing Using Electrical Impedance Pneumography Intended for the Diagnosis of Chronic Obstmc-tive Pulmonaiy Disease Patients, Sensors, 13(11), pp. 15846-15860... 

By increasing the probe diameter, we bring down tlie impedance point along the impedance curve with the same way as the electrical frequency or conductivity. We will describe only one type of probes, namely, the probe with ferritic circular section that we could qualify as punctual with an optimal sensibility. In order to satisfy these conditions, tests will be made to confirm these results by ... 

Electrochemical tests This group includes the various electrochemical tests that have been proposed and used over the last fifty or so years. These tests include a number of techniques ranging from the measurement of potential-time curves, electrical resistance and capacitance to the more complex a.c. impedance methods. The various methods have been reviewed by Walter . As the complexity of the technique increases, i.e. in the above order, the data that are produced will provide more types of information for the metal-paint system. Thus, the impedance techniques can provide information on the water uptake, barrier action, damaged area and delamination of the coating as well as the corrosion rate and corroded area of the metal. However, it must be emphasised that the more comprehensive the technique the greater the difficulties that will arise in interpretation and in reproducibility. In fact, there is a school of thought that holds that d.c. methods are as reliable as a.c. methods. 

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