Impedance spectroscopy validation

One of the most important applications of neural network methodology is in the extrapolation of electrochemical impedance data obtained in corrosion studies.34 Electrochemical impedance spectroscopy (EIS) can be used to obtain instantaneous corrosion rates. The validation of extension of EIS data frequency range, which is conventionally difficult, can be done using a neural network system. In addition to extension of impedance data frequency range, the neural network identifies problems such as the inherent variability of corrosion data and provides solutions to the problems. Furthermore, noisy or poor-quality data are dealt with by neural works through the output of the parameters variance and confidence.33... 

Popkirov GS, Schindler RN (1993) Validation of experimental data in electrochemical impedance spectroscopy. Electrochim Acta 38 861-7... 

Darowicki K, Kawula J (2004) Validity of impedance spectra obtained by dynamic electrochemical impedance spectroscopy verified by Kramers-Kronig transformation. Pol J Chem 78(9) 1255-60... 

The lack of uniqueness of circuit models creates ambiguity when interpreting impedance response using regression analysis. A good fit does not, in itself, validate the model rised. As discussed in Chapter 23, impedance spectroscopy is not a standalone technique. Additional observations are needed to validate a model. 

While the nature of the error structure of the measurements is often ignored or understated in electrochemical impedance spectroscopy, recent developments have made possible experimental identification of error structure. Quantitative assessment of stochastic and experimental bias errors has been used to filter data, to design experiments, and to assess the validity of regression assumptions. 

The statistical properties described above for frequency-domain stochastic errors are based on the equations for the instruments actually used for the measurement of complex quantities. While the statistical properties are developed here for electrochemical impedance spectroscopy, they are also valid for measurement of other complex quantities so long as the complex quantities are measured through similar physical principles. 

Remember 23.2 Impedance spectroscopy is not a standalone technique. Other observations are required to validate a given interpretation of the impedance spectra. 

P. K. Shukla, Stationary Hemispherical Electrode under Submerged Jet Impingement and Validation of the Measurement Model Concept for Impedance Spectroscopy, Ph.D. dissertation. University of Elorida, Gainesville, FL (2004). 

E. V. Gheem, R. Pintelon, J. Vereecken, J. Schoukens, A. Hubin, P. Verboven, and O. Blajiev, "Electrochemical Impedance Spectroscopy in the Presence of Non-Linear Distortions and Non-Stationary Behavior I. Theory and Validation," Electrochimica Acta, 49 (2006) 4753-4762. 

Urquindi-Macdonald M and Egan P C 1997 Validation and extrapolation of electrochemical impedance spectroscopy data Coir. Rev. 15 169... 

After introduction a prototype of intelligent multi-sensor system for driver status monitoring— DeCaDrive is presented in Section 2. The system expansion with embedded impedance spectroscopy sensor, its analog front-end and sensor data preprocessing are addressed in Section 3. Multi-sensor feature computation and data fusion as well as neural network based pattern classification are discussed in Section 4. The extended system is validated and evaluated by presenting the experimental results in Section 5. Finally, with future perspectives the current work is concluded in Section 6. 

Electrochemical impedance spectroscopy is a mature technique, and its fundamental mathematical problems are well understood. Impedances can be written for any electrochemical mechanism using standard procedures. Modem electrochemical equipment makes it possible to acquire data in a wide range of frequencies and with various impedance values. The validity of experimental data can be verified by standard procedures involving Kramers-Kronig transforms. Several programs either allow for the use of predefined simple and distributed elements in the construction of electrical equivalent circuits or directly fit data to equations (which should be defined by the user). 

Strik, D.P., Ter Heijne, A., Hamelers, H.V.M., et al., 2008. Feasihihty study on electrochemical impedance spectroscopy for microbial fuel cells measurement modes data validation. Meeting Abstracts. MA2008—01 243. 

Song, H. and Macdonald, D.D. (1991) Photoelectrochemical impedance spectroscopy I. Validation of the transfer function by Kramers-Kronig transformation. Journal of The Electrochemical... 

Experimentally, there are several ways to determine the ohmic cell resistance. If the V-I curve has a substantial linear portion (in the center), the slope of this curve usually closely approximates the ASR of the cell. Only in such a linear portion of the V-I curve the ohmic resistance is dominant, and hence the determination of the ASR valid. Sometimes, a more accurate way to determine the ohmic resistance is from impedance spectroscopy. In an impedance spectrum of a fuel cell, the ohmic resistance is the real value of the impedance of the point for which the imaginary impedance is zero (Figure 2-5). As can be seen in the example, the ohmic resistance is invariant with gas concentration. The part of the impedance that is related to mass transport and kinetics, however, changes markedly with anode feed composition. 

ABSTRACT Eddy current (contactless) measurements, especially in the form of the impedance spectroscopy, could be elfectively used to determine the electrical properties, including conductivity, of various materials, tissues and objects in many industrial, medical and other applications (e.g. coin validation). One important aspect is to have the cahbration standards for the adjustment of eddy current instrumentation to guarantee repeatabUity and comparability of the measurements. In the paper, there is described an experimental study carried out to find the ways to improve and correct the theoretical eddy current models for the single coil above the metal plate setup, designed for measurements without using of the reference metal specimen with known electrical properties. The final results show, that the accuracy of measurement with a single-coil setup can be better than 0.5% in the 60 to 500 kHz frequency range and 3.0% at the frequencies up to 10 MHz, all valid for conductivity values from 2.5 to 25 MS/m. 

Urquidi-Macdonald, M., and Egan, P. C., Validation and Extrapolation of Electrochemical Impedance Spectroscopy Data, Corrosion Reviews, 15 169-194 (1997). 

In this regard perturbation analysis like step analysis and electrochemical impedance spectroscopy (EIS) can show the way (Choudhury et al., 2005, Jenseit et al., 1993). The popular trend of using transmission line model for EIS analysis may not be sufficient to diagnose the dynamic mechanisms. Thus to understand and decouple the effects, there is a need to develop and validate comprehensive transient models based on first principles. With the availability of increased computational power it may be possible to develop online fault diagnosis analyzer systems for the actual field units. 

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