Admittance homogeneous

For a homogeneous sample, film admittance is related to its physical... 

Given the nature of the polymer and the conduction pathway, a simple homogeneous model cannot be applied to thin conducting polymer film-electrolyte systems [27,28,31]. For thin films (< lOOnm) with pore sizes estimated to range from 1 to 4 nm, the porous surface-electrolyte interface will dominate the electrical and physical properties of the sensor. Since the oxidation of the porous surface occurs first, the interface properties play a major role in determining device response. To make use of this information for the immunosensor response, the appropriate measurement frequency must be chosen to discriminate between bulk and interface phenomena. To determine the optimum frequency to probe the interface, the admittance spectra of the conducting polymer films in the frequency range of interest are required. 

We revert to the basic capacitor model of Figure 3.1. The admittance Y of the capacitor is (sinusoidal AC voltage u, homogeneous dielectric, and no edge effects) ... 

Based upon Faraday s work, James Clerk Maxwell published his famous equations in 1873. He more specifically calculated the resistance of a homogeneous suspension of uniform spheres (also coated, two-phase spheres) as a function of the volume concentration of the spheres. This is the basic mathematical model for cell suspensions and tissues still used today. However, it was not Maxwell himself who in 1873 formulated the four equations we know today as Maxwell s equations. Maxwell used the concept of quaternions, and the equations did not have the modern form of compactness he used 20 equations and 20 variables. It was Oliver Heaviside (1850—1925) who first expressed them in the form we know today. It was also Heaviside who coined the terms impedance (1886), conductance (1885), permeability (1885), admittance (1887), and permittance, which later became susceptance. 

In addition to the impedance, other derived quantities, such as the dielectric modulus (M), the complex dielectric constant (e), or susceptibility (x), can be calculated from the IS measurements their interrelations have been tabulated elsewhere (Macdonald 1987). Complementary information on the dielectric response of a given system can be obtained from the different impedance plots and the related magnitudes. It is important to point out the different nature of these magnitudes extensive or sample geometry dependent in the case of impedance or admittance, and intensive or characteristic of homogeneous materials in the case of conductivity and the dielectric constant. 

In the restricted frame of small amplitude signals and homogeneous, isotropic, and linear properties, the complex admittance is deduced from the previous equation by Fourier transformation... 

The optical admittance of a single traveling wave in a homogeneous medium of refractive index is called the wave admittance of that medium, /,. For a p-polarized light wave. 

The optical model is also shown in Fig. 2. The interfaces are parallel to the x,j-plane, the system is assumed to be laterally homogeneous, but the refractive index changes in the direction normal to the interfaces, and this change is abrupt at the water-air interface inside the layer. If the thickness of the layer d) is much less than the wavelength, the most convenient way to calculate the reflectance is in terms of the optical admittance. 

Table 3.3a shows the calculated results of the impedance, the admittance, the modal attenuation constant, and the propagation velocity on the solidly bonded case Table 3.3b shows the results on the cross-bonded case with the homogeneous model at frequency f = 100 kHz. 

Homogeneous Model of a Cross-Bonded Cable 3.2.3.1 Homogeneous Impedance and Admittance... 

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