Choice of Electrode Material for Detecting Low Frequency Electric Field in Sea Water

Abstract

Seven types of electrodes have been selected. DC resistances, AC impedances and voltage difference of the electrode pairs have been studied, according to the requirement of low and extra low frequencies electric fields detection in sea water. The feasibilities of these electrodes used for detecting these signals have been studied and explained on theories. The results show that the all-solid-state Ag/AgCl electrode is the most sensitive electrode with its very low DC resistances, AC impedances and the voltage difference controlled within 20μV, which makes it detecting low frequency electric field accurately.

Investigation of the AgCl Formation Mechanism on the Ag Wire Surface for the Fabrication of a Marine Low-Frequency-Electric-Field-Detection Ag/AgCl Sensor Electrode

“…The sensor electrodes used for the LFEFD in the marine environment have a high demand for having low resistance values at low-frequency signals for high detection sensitivity . Thus, the electrode resistance values at 1 Hz under sine wave excitation signals of 5 or 10 mV are widely used to represent an important parameter of the electrochemical performance of the sensor electrodes. , In this part, we compare the resistance values of the Ag/AgCl electrodes fabricated under conditions of various constant current magnitudes and anodization times and connect them with the surface structure of the electrodes including AgCl deposits.…”

“… 12 As a result of these properties, it has lower resistance and impedance with the stability of electrode voltage, that is, a very small self-noise in seawater, making itself suitable for its use of the marine weak low-frequency electric field detection (LFEFD), compared to other electrodes such as zinc, graphite, and saturated calomel electrodes, and even better than carbon fiber electrodes. 12 …”

“…4,11−13 In particular, the Ag/AgCl electrode with AgCl coatings on the Ag surface is robust and nonpolarizable and has a single electric conductive ion, Cl − and establishes the fast electrochemical equilibrium with Cl − containing seawater. 12 As a result of these properties, it has lower resistance and impedance with the stability of electrode voltage, that is, a very small self-noise in seawater, making itself suitable for its use of the marine weak low-frequency electric field detection (LFEFD), compared to other electrodes such as zinc, graphite, and saturated calomel electrodes, and even better than carbon fiber electrodes. 12 The common methods to fabricate the Ag/AgCl electrode include the electrolytic process, 1,3,13,14 hot dipping process, 15 and sintering process.…”

“…12 As a result of these properties, it has lower resistance and impedance with the stability of electrode voltage, that is, a very small self-noise in seawater, making itself suitable for its use of the marine weak low-frequency electric field detection (LFEFD), compared to other electrodes such as zinc, graphite, and saturated calomel electrodes, and even better than carbon fiber electrodes. 12 The common methods to fabricate the Ag/AgCl electrode include the electrolytic process, 1,3,13,14 hot dipping process, 15 and sintering process. 16 Among them, the electrolytic process in which constant current (i.e., chronopotentiometry) or potential (i.e., chronoamperometry) is applied has the Ag electrode connected to the working electrode probe of the work station and anodized in the chloride-containing such solutions like HCl, KCl, and NaCl to form the AgCl layers on the electrode surface.…”

“…The Ag/AgCl electrode is one of the most widely used electrodes. − Its applications range from its use in the reference electrode, ,, through as the sensor determining the chloride content in reinforced concrete structures to assess the probability of chloride-induced corrosion of steel reinforcements in them, ,− to the detection of electric field signals in seawater. ,− In particular, the Ag/AgCl electrode with AgCl coatings on the Ag surface is robust and nonpolarizable and has a single electric conductive ion, Cl – and establishes the fast electrochemical equilibrium with Cl – containing seawater . As a result of these properties, it has lower resistance and impedance with the stability of electrode voltage, that is, a very small self-noise in seawater, making itself suitable for its use of the marine weak low-frequency electric field detection (LFEFD), compared to other electrodes such as zinc, graphite, and saturated calomel electrodes, and even better than carbon fiber electrodes …”