Marine Electric Field Observations With Variable Dielectric Polarization

Stability of marine electric fields measurements is a problem of broad interest in relation to long-term in situ observations, especially in the construction of the Internet of Underwater Things (IoUT), geological exploration, and disaster monitoring. The root of this problem is the drift in electrode potential caused by imbalances in the electrodes’ electrical processes, which are unavoidable in potential-difference measurements based on the conduction current. Here, we propose the variable dielectric polarization (VDP) measurement method, which uses the variation of a dielectric between the electrodes to measure the external electric field. This method modulates the electric field signal to higher frequencies, allowing separation of the signal from the output by demodulation. This not only separates the signal from low-frequency noise, but it also increases the measurement sensitivity by frequency boosting. The results of our experiments show that the VDP system we constructed has a measurement sensitivity of 2.63 V/(V/m) and a measurement resolution of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$22.4~\mu $ </tex-math></inline-formula>V/m. Under long-term measurements, the measured drift of the VDP system (106 (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>V/m)/day) was found to be only 1/320 of the self-potential (SP) method (34 (mV/m)/day). The proposed VDP method, thus, provides a new approach to the construction of future IoUT devices and the prediction of marine disasters.