Electrical impedance properties

The first commercially successful automated blood cell counter, the Model A Coulter Counter, was introduced in 1956. The Model A counted cells by using electrical impedance properties, and the Coulter Counter quickly became the instrument of choice for counting red and white blood cells. When it was later demonstrated that cell volume was roughly proportional to the electrical impedance signal amplitude, the Coulter Counter was modified to provide MCV as the mean of the individually measured red cell volumes. Impedance counters calculated HCT as (RBC x MCV)/10 and, by the early 1970s, these instruments also counted platelets. By the mid-1970s, impedance counters combined with photometric hemoglobinometers to produce CBCs. 

This kind of fractals sometimes is identified with deterministic constructions like Cantor set (in P), Sierpinski triangle or Sierpinski square (in P ), with Sierpinski pyramid or Menger sponge (in P ), and so on. In our case of electric impedance property. 

Electrical Impedance Properties of Chemically Responsive Hydrogels... 

So D S, Kang I, Huh H and Lee H (2010) Electrical impedance properties of carbon nanotube composite electrodes for chemical and biosensor, J Nanosci Nanotechnol 10 3449-3452. 

Polar Cell Systems for Membrane Transport Studies Direct current electrical measurement in epithelia steady-state and transient analysis, 171, 607 impedance analysis in tight epithelia, 171, 628 electrical impedance analysis of leaky epithelia theory, techniques, and leak artifact problems, 171, 642 patch-clamp experiments in epithelia activation by hormones or neurotransmitters, 171, 663 ionic permeation mechanisms in epithelia biionic potentials, dilution potentials, conductances, and streaming potentials, 171, 678 use of ionophores in epithelia characterizing membrane properties, 171, 715 cultures as epithelial models porous-bottom culture dishes for studying transport and differentiation, 171, 736 volume regulation in epithelia experimental approaches, 171, 744 scanning electrode localization of transport pathways in epithelial tissues, 171, 792. 

In another type, mammalian cells or plasma membranes are used as electrical capacitors. Electrical impedance (El) uses the inherent electrical properties of cells to measure the parameters related to the tissue environment (Kyle et al., 1999). The mechanical contact between cell-cell and cell-substrates is measured via conductivity or El (Deng et al., 2003 ... 

Johannsmann et al. have reported the use of quartz crystal electrical impedance to study the viscoelastic properties of poly(y-methyl-L-glutama-te-co-y-zi-octadecyl-L-glutamate) thin films [65, 66] and Ward studied the viscoelastic characteristics of poly-styrene films with 2-chloro-toluene solvent by measuring the admittance near resonance at 5 MHz of the unloaded quartz resonator and the composite resonator [67]. 

The fundamental kinetics and transport properties of plasma processes are reviewed and applied to polysilicon etching in Cla discharges. The relative neutral flux, ion flux, and ion energy is critical in controlling the directionality of the etching process. The electron density and energy have been estimated from electrical impedance measurements of Cl2 discharges. 

To control whether stimulation was successful we continuously recorded the impedance spectra of the cell cultures for 1 h. As published before the stimulation causes an impedance increase at around 17.5 kHz [3]. Nevertheless, these measurements reflect an unrealistic state where the cells are cultivated on the electrodes. Therefore, we also measured the electrical properties of the medium without growing cells on the electrode to describe the status when the neutrophils arrive and exclude their chromatin in the wound. To determine the electrical medium properties we used the cultivation medium as a reference in a new well. The top layer of cell medium in the cell culture was discarded after a stimulation period of 1 h. The remaining bottom layer containing mostly NETs was suspended in the new well. For the unstimulated control sample this medium contains mostly unstimulated cells. All displayed spectra are representatives for one well. 

Modeling the vascular system for dynamic impedance signal simulation has been rarely done. This is mostly because of the complexity of the vascular system dynamics and the dynamics of the resulting electric/dielectric properties. The vascular system and its dynamics has been extensively modeled and simulated from the perspective of mechanical parameters—pulse wave dynamics and flow rates. These models are often compared with in vivo or in vitro studies and the results are positive [2], [3]. 

For the dynamic lung impedance model to be useable in Finite Difference Method or Finite Element Method impedance signal simulations, the dynamic tissue sample model is discretized into volume data. At first 3D data with 35 x 35 x 35 voxel resolution is prepared from each of the 40 time frames. This allows for easy import into MATLAB or COMSOL based calculation. The volume data includes percentage of blood vessels (blood) for each of the 35 X 35 X 35 X 40 voxels. It can readily be transformed into electric/dielectric properties for each voxel with tissue data available on the internet. But data can also be exported with arbitrary resolution depending on calculation-simulation requirements. The simulations are run separately for each of the 40 time-frames to get full frequency characteristic of impedance measurement across the tissue sample. Finally we can get 40 frequency characteristics—one for each time-frame and to see a dynamic electrical impedance signal on a certain frequency, we just need to plot the impedance value at the chosen frequency from the 40 time-frames. 

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