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.

Engineering two-dimensional pores in freestanding TiO_2/graphene gel film for high performance lithium ion battery

As the key component of electrochemical energy storage devices, an electrode with superior ions transport pores is the important premise for high electrochemical performance. In this paper, we developed a unique solution process to prepare freestanding TiO_2/graphene hydrogel electrode with tunable density and porous structures. By incorporating room temperature ionic liquids（RTILs）, even upon drying, the non-volatile RTILs that remained in the gel film would preserve the efficient ion transport channels and prevent the electrode from closely stacking, to develop dense yet porous structures. As a result, the dense TiO_2/graphene gel film as an electrode for lithium ion battery displayed a good gravimetric electrochemical performance and more importantly a high volumetric performance.