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Compact measurement setup and test structure for nanosecond electroporation of biological cells were demonstrated. The test structure was based on a coplanar waveguide with a defected ground structure that afforded broadband impedance match with little dispersion or parasitic. The defected ground structure with a 10-µm gap formed a microchamber to readily accept biological solutions and to allow the...
Nanosecond electroporation has a range of applications including gene therapy and treatment of melanoma tumors. On applying a nanosecond high voltage pulse, potential differences are generated across the membranes of the internal organelles resulting in its electroporation. This paper investigates the effect of nanosecond high voltage pulses simulated on a biological cell placed in a conductive medium...
In order to model nanosecond pulse electroporation of the cell membrane the effect of dielectric relaxation of membrane molecules has to be considered. Since the formation of pores is a nonlinear process the dielectric relaxation effects have to be incorporated as dispersion in the time-domain. This paper presents the time-domain implementation of a second-order Debye dispersion model for a single-shell...
When applying an AC electric field on biological cells, the permittivity and conductivity of cell suspension changes with the frequency of the applied electric field. This phenomenon is commonly known as dielectric relaxation effect. It can be used to predict dielectric properties of cells in blood. It can provide a new medical diagnosis approach to study the electrophysiological characteristics of...
This paper demonstrates the detailed electromagnetic modelling of biological cell structures by using modified subgridding FDTD techniques. This is done by incorporating a quasi-static FDTD solution, Floquet periodic boundary conditions and modified PML boundary conditions to achieve microdosimetric modelling of bioelectromagnetic interactions at cellular level. Particular attention is paid to exploration...
To study the effect of lead ion on the activity of roots of mung bean seedlings, the experiment adopts five kinds of different concentration lead ion to treat with the mung bean seedling, The results show that the higher concentration lead ion treatment resulted in lower activity of mung bean seedlings roots, and lessen protoplasmic surface charge of roots and the rate of electrophoresis migration...
The initial response of a cell to an applied electric field is determined by its dielectric properties. Conversely, exposure to an electric field can alter these parameters. Hence, an understanding of dielectric membrane phenomena helps in explaining the underlying interaction mechanisms. Moreover, different electrical characteristics might also allow devising exposure conditions for pulsed electric...
This report is devoted to study an individual influence of millimetric EM field components on the alive cells. It should be emphasized that the action of E- and H-components will be differential according to structure and orientation of the object. Influence can be simulated by interaction between the EM-field and electrical or magnetic dipoles. Naturally, physical mutter of this processes will be...
Biological cells stressed by external electric fields undergo mechanical deformation and remodeling caused by electro-mechanical Maxwell stresses. These stresses appear at the internal and external membrane interfaces due to differences in dielectric properties of the biological membrane and the surrounding and internal fluids. Electro-mechanical loading of the cells results in the reversible or irreversible...
This work presents the basic design and tests of a device designed for detecting the contact between a microinjection pipette and cell membrane. The device facilitates the automation of the microinjection procedure of living adherent cells. The measurement of the contact is based on measuring the resistance of the pipette. Breakage and clogging of the pipette can be detected with the same measurement.
Highly intimate contact between an electrode and a living neuron is strongly desired by both basic neuroscientists and engineers seeking to develop more effective neural prostheses. The net resistance between electrode and cell must be decreased in order to improve the quality of recordings and deliver the minimum necessary stimulating current specifically to the target cell. The ideal situation would...
Measurements of cell membrane capacitance serve as an indicator of cell membrane surface area and thus have traditionally been used in stimulus-secretion coupling to monitor exocytosis and endocytosis of secretory vesicles. In order to accurately monitor secretion, high-resolution methods of tracking small (10/sup -15/ F) changes in baseline capacitance must be utilized. Most presently used techniques...
Quantitative understanding of electroporation in a multicellular system has been limited. The transient aqueous pore theory describes electroporation as the stochastic formation of hydrophilic pores in the presence of an applied electric field. We have used an asymptotic model for local membrane electroporation in a transport lattice system model to predict effects of a electrical pulse on a didactic...
Electrical models for biological cells predict that reducing the duration of applied electrical pulses to values below the charging time of the outer membrane causes a strong increase in the probability for electric field interactions with intracellular structures. For electric field amplitudes exceeding MV/m, such pulses are expected to cause electroporation of cell organelles, with the required...
It has been shown that low-power ultrasound (US) has a significant effect on the rate of fresh fracture healing in animals and humans. The action of US can involve a direct mechanical effect (microstrain) or an indirect electrokinetic effect. To test the electrokinetic hypothesis, a four-electrode measurement technique is used to evaluate the effects of externally applied US on cell membrane impedance...
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