A Comparative Study of the Electrodes Gels’Electrical Properties in the Measurement Issues of Intrabody Communication

Intrabody communication(IBC)technology is becoming progressively more standard-ized due to its low power consumption and high security features incorporated into the third phys-ical layer of the IEEE 802.15.6 standard.Even then,there are still many challenges in normalizing the measurement issues of IBC.A major concern that should not be overlooked is the electrodes in the IBC,especially the popular use of gel electrodes.In the channel measurements,gel electrodes are commonly employed to improve the signal-to-noise ratio and prevent electrodes from falling off.In this paper,a comparative study of the electrical properties of gel was investigated during the measurement of human channel characteristics and to clarify the differences of them.Firstly,the basis of electrostatic field pole plate measurements and electromagnetic theory were introduced to interpretate how the relative permittivity and conductivity of different gels will influence the meas-urement results.Then the in vivo experiments with different gel or dry electrodes were performed to compare the differences induced by the gel.The results indicate that the influence of the gel on the human channel measurement is mainly concentrated below 400 kHz(the attenuation is re-duced by 16.7 dB on average),and the stability of the permittivity and conductivity of the gel has a direct impact on the stability of its measurement of the human channel.This result may provide a meaningful reference for the standardization of electrode usage in IBC.

Comparative Study on Galvanic-Coupled Intrabody Channel Characteristic Measurement Methods

The galvanic-coupled intrabody communication(GCIBC)uses the human body as the channel for data transmission.The signal flow through different paths within different measure-ment schemes,resulting in distinct deviations in the experimental results.This method completely uses human body channel to transmit low-power signals,and has good anti-interference perform-ance.However,for a long time,the channel research of GCIBC has not determined a set of recog-nized and accurate measurement methods and standards.However,few researcher analyze the dif-ferences and principles between different measurement methods.This paper aims at three com-monly used measurement methods.Abstract the equivalent schematic diagrams of three measure-ment schemes:direct measurement,using high-precision differential probe and using balun.The sig-nal return paths generated by three measurement methods are analyzed,the impedance matching and energy transmission efficiency are compared.According to the analysis,the empirical expres-sions in different cases are listed.The mechanism between the channel measurement results gener-ated by the set experimental configuration and the comparison experiment is clarified.The compar-ison experiment with complete floating measurement is carried out as a reference to verify the pro-posed opinion.The measurement error caused by different experimental configurations is verified.This study can provide a reference opinions for the experimental error analysis of GCIBC research in the future,and provide suggestions for the selection of experimental configuration.