Conformal Curved-Electrode Sensor with High-Frequency Optimization for Distributed Conductivity Monitoring in Shipboard Desalination Pipelines

Current seawater desalination systems on ships face several limitations including outdated concentration detection methods, low detection accuracy, and insufficient real-time monitoring capabilities. This study addresses these issues by developing a concentration measurement device based on two-electrode conductivity measurement principles. The key innovation involves transforming conventional parallel plates into curved electrode plates that can be embedded directly into pipelines, enabling real-time concentration monitoring in shipboard seawater desalination systems. We established an equivalent circuit model and conducted simulation analysis of amplitude–frequency and phase–frequency response characteristics to guide excitation signal frequency selection. Using 3D printing technology, we fabricated pipeline components and manually processed curved electrode plates, then assembled experimental devices and determined optimal working parameters through systematic measurements of solution conductivity versus frequency and concentration. Laboratory testing with known concentration saline solutions demonstrated high measurement accuracy, with the device achieving a relative error of only 1.457% for 3.5% NaCl solution (simulated seawater) and 3.000% for commercial saline (0.9% NaCl) after calibration. Finally, we integrated a PLC control system for automated concentration measurement and display. Compared to traditional devices that require sampling in static water environments, this system can be distributed throughout shipboard desalination systems, providing more convenient, accurate, and efficient monitoring capabilities.