A “Self-Sufficient” In Situ Marine Electric Field Observing System

In-situ marine electric field sensing is an effective means of exploration for marine geological activities. Dynamic modulation measurement is commonly used in measurement solutions due to stability requirements in in-situ measurements. However, the high energy requirements of modulation measurement is a challenge underwater field. In this paper, we realise passive modulation measurements by utilising the low permittivity of bubbles. Further, we also utilise the energy of the bubbles to power the measurements, so to realise a self-powered in-situ electric field measurement system. Experiments show that the limit of detection (LOD) of the proposed passive bubble-modulated polarization method is 0.1 mV/m and the drift (1.42 × 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−4</sup> (V/m)/day) is 1.2% of that of the conventional static measurement methods (1.1 × 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−2</sup> (V/m)/day). The energy consumption of the proposed passive modulated measurement system (0.825 mW) is 2.75×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−5</sup> of the conventional modulated measurement system (30 W). This paper truly realizes an in-situ long-term detection system that integrates energy supply and measurement, which can promote the exploitation of cold springs and hydrothermal fluids and the construction of the Internet of Underwater Things in these regions.