Modified carbon fiber electrodes with enhanced impedance performance for marine sensor

At present, the use of carbon fiber electrodes as marine sensors for marine signal exploration has received much attention. AC impedance is the crucial factor affecting the performance of sensor. Unfortunately, the AC impedance performance of carbon fiber electrodes has been underappreciated up to date. In order to fully understand the influencing factors of AC impedance, the comprehensive and systematic study was carried out in terms of reference electrode type, encapsulated shell of electrode, immersion depth of electrode, obstacles between electrodes, electrode position, initial voltage electrolyte concentration and electrolyte type. Through analog equivalent circuits, the solution impedance R₁, charge transfer impedance R₂ and diffusion impedance W₁ were found to be 1.485, 0.313 and 1.158 Ω, respectively. The smallest impedance of silver-plated carbon fiber electrodes is only 3.49 Ω at 1 Hz. Combined with different influencing factors, we can know that the modified carbon fiber electrodes performance was mainly controlled by diffusion and transfer processes. This study would contribute to the design and application of the silver-plated carbon fiber electrodes as marine electric field sensor.