| Intra-body communication(IBC)was a technology of using human body as electrical signal transmission medium,which has the advantages of low power consumption,no need of antenna design,convenient connection,reducing the risk of remote eavesdropping,etc.Furthermore,an effective communication between wearable devices can be achieved by applying IBC technology.Before the widely application in wearable intelligent products,the electromagnetic safety must be quantified.At present,the research of electromagnetic safety was mainly aimed at high frequency or high voltage signal,but the research on weak electrical signal such as IBC signal was lack.In this paper,International Commission Non-Ionizing Radiation Protection(ICNIRP)guidelines were used to evaluate the safety of IBC signal,to analyze the impact of IBC weak electrical signal on the human body from both macroscopic and microcosmic view.This research is significance for the further application of IBC.The specific contents are as follows:First of all,a 3D arm model of the experiment subject was built,which was based on CT image.In order to accelerate the reconstruction process and improve computational efficiency,a geometric abstract model was used,and the validity of the abstract model has been verified.Therefore,the geometric information of the important tissues in the human arm was acquired to establish a four dimensional geometric model of human arm.The finite element model of human arm was established,based on the dielectric properties of human tissues,the communication control equation of human body under the quasi-static electric field approximation,and the boundary conditions of the human body and the air,or the skin and the electrodes.The models were optimized by the IBC in vivo experiment,then the more realistic communication arm models were built.Secondly,the finite element analysis of the models were carried out.The results show that,with the increase of signal frequency,the electric field intensity of each tissue layer decreases gradually,and the skin effect occurred at high frequency.From the electromagnetic point of view,the method of virtual measurement have been employed to explore the changes of the current density and the specific absorption rate of human body with different signal frequency and intensity.Moreover,the effects of different arm length and circumference for experimental results are also evaluated.The experimental results of the current density and the specific absorption rate of human body show that there are no influence on the human body by using the weak IBC signal,based on the basic limits of public exposure in ICNIRP guidelines.Finally,to study the biological effects of the IBC signal from the cytology level,the electrical stimulation system,which included an adjustable AC constant current source,was built to output the characteristics of galvanic coupling IBC signal.And the human body cells cultured in vitro for the long term electrical stimulation experiment.The growth-condition of cell was observed under the microscope,which can reflect the effect of IBC signal visually.The cell survival rate was detected by MTT assay.The experimental results showed that the survival rate of the cells was 90%-100%.Statistically speaking,the weak signal of IBC would not affect the human cells.In this paper,by means of electromagnetic simulation and biological evaluation,it can conclude that the impact of weak signal of IBC on the human body was far below the risk level.The conclusion can provide a reliable basis for the practical application of IBC technology in the future. |
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