چكيده به لاتين
The increasing use of electromagnetic wave-generating devices in our daily life has cause many worries concerning the effects of such devices on human health. Since human neurons are responsible for transferring the neural signals, which are derived from propagation of ions, these cells can be considered as the important thing that the body and electromagnetic fields have in common. On this basis, the present study is aimed to investigate the neurons’ function under radiation of the electromagnetic fields. A method is proposed for 3D modeling of neurons in presence of any kind of stimulants of direct or indirect current or voltage; accordingly, the electric scalar potentials and magnetic vector potential were used. Electromagnetic features of the environment were considered as dependent on time and electric field, so that the nonlinear behavior of membrane could be analyzed; furthermore, effect of the strong static magnetic fields on neurons were expressed considering the forces applied on the magnetophoretic and mobile ions. Several examples were given to prove validity of the model in accordance with the references. Due to the importance of this issue and also regarding the fact that the available models are mainly preliminary, for the first time, it has been proposed to present equations as well as a model for simulating and predicting the neurons’ behavior under radiation of the electric and magnetic fields. In summary, it can be said that, using this model, it would be possible to assume any 3D shape of the cell, analyze the cell’s activity under various physical conditions, obtain the neural signals and fields resulted from the cell’s activity, and analyze various stimulants simultaneous with the cell’s activity in order to appropriately investigate effects of the static and time-variant electromagnetic fields on activity of the cell. Subsequently, an example of the useful applications of this modeling and two other examples of designing were presented. The first application was to extract the electromagnetic signals resulted from the neurons’ activity within the nervous system, which is used for analysis of MEG and EEG signals. In the next step, in order to transfer the signal from a damaged neuron to the healthy ones, an electromagnetic connector was designed and then simulated in the 3D model. According to this simulation, the two neurons, which are in a 35cm distance from each other, could be also connected by this connector. The structure and material of this connector, which can be made of the body-compatible polymers, have been reported; moreover, design and implementation of an electromagnetic system for creating anesthesia in the spinal cord have been proposed and reported. This system was created by designing an array of windings, time-shape of the source current, and field rectifier layer. Finally, the common transmission method was investigated and improved. First, the given equation was derived from the current continuity equation; then, it was shown that what approximation has been assumed by previous method, indicating significant errors in frequencies lower than 100Hz. afterwards, since these equations are solved by discretization method, a fast and stable discretization method was proposed for simulating the neurons. Furthermore, since the biological environments have frequency dispersion, the method for consideration of this issue is proposed within the time. The obtained results showed that since permittivity of the environment was reduced at higher frequencies, if this phenomenon was taken into consideration, the resulted error would be increased at stimulants with frequency higher than 1 KHz; besides, it would become possible to analyze the noise of signals by modeling the dispersion.
