Capacitive Underwater EM Sensor Package for Low-Noise Measurement
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Solution Overview
Problem
Existing underwater electromagnetic measurement systems are cumbersome, prone to corrosion, and suffer from high noise levels due to the need for large resistive electrodes that require complex ion exchange processes, making them difficult to assemble and deploy, and limiting their accuracy and reliability.
Innovation Solution
A compact electromagnetic measurement system using capacitive electrodes with a conducting core and insulative layer, integrated into a single pressure vessel with magnetic and electric field sensors, minimizing resistive current flow and electrochemical reactions, and allowing for pre-deployment testing and calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If large separation between electrodes is used to improve measurement accuracy, then measurement precision is improved, but device complexity and size increase
Solution Approach 1:
The patent combines multiple sensors (magnetic induction coils, electric field electrodes, navigation, data logging) into a single integrated pressure vessel, eliminating the need for separate mounting structures and complex interconnections. This integration maintains measurement accuracy while significantly reducing system complexity and deployment difficulty.
Solution Approach 2:
The patent nests all sensor elements and electronics within a single pressure vessel, with sensors mounted on internal surfaces and electronics housed in sealed compartments. This nested arrangement achieves the required electrode separation for accurate measurements while containing the entire system in a compact, deployable unit.
2Use of energy by moving object
If resistive electrodes are used to enable current flow through seawater, then electrical conduction is achieved, but corrosion and noise increase
Solution Approach 1:
The patent introduces a high-impedance buffer amplifier as an intermediary between the electrodes and the measurement system. This buffer minimizes the current drawn from the electrodes, reducing electrochemical reactions and corrosion while maintaining accurate voltage measurements. The buffer acts as a mediator that allows electrical conduction without the harmful side effects of resistive current flow.
Solution Approach 2:
The patent changes the electrical parameter of the measurement system by using high-impedance input amplifiers (≥10^9 ohms) instead of low-impedance resistive connections. This parameter change reduces the current flow through the electrodes by several orders of magnitude, thereby minimizing corrosion and electrochemical noise while maintaining measurement capability.
3Ease of manufacture
If discrete modules with connectors are used to interface sensors, then system assembly is flexible, but connector leakage and corrosion risk increase
Solution Approach 1:
The patent merges all sensor modules, electronics, and interconnections into a single sealed pressure vessel. This eliminates external connectors and cables that are prone to leakage and corrosion, while maintaining assembly flexibility through modular internal mounting of sensor elements within the sealed housing.
4Manufacturing precision
If complex assembly on ship deck is required to deploy the system, then system configuration is precise, but deployment time and operational complexity increase
Solution Approach 1:
The patent performs all system assembly, configuration, and testing operations in advance during manufacturing, resulting in a pre-configured, sealed pressure vessel. This preliminary action eliminates the need for complex on-deck assembly operations, reducing deployment time while maintaining precise system configuration through factory-controlled assembly procedures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system is more robust, easier to use, and significantly reduces noise and size, enabling more accurate and reliable measurements of electric and magnetic fields in underwater environments, with improved durability and reduced operational complexity.
Implementation Method 1
The capacitive electrode has a capacitance to the water of greater than 1 mF in the capacitive regime from 0.1 Hz to 10 Hz
Implementation Method 2
Each magnetic field sensor has a magnetic field induction coil for producing a magnetic field signal
Implementation Method 3
Each electric field sensor receives an input from at least two electric potential antennas and produces an electric field signal by amplifying and differencing the signals from the electric potential antennas
Data Source
AI summary
An underwater EM measurement system, which is substantially smaller, much simpler to use, and more robust than prior systems, is formed as a sensor package integrated into a single pressure vessel includes two magnetic sensors including induction coils disposed substantially horizontally so as to measure fields in orthogonal directions. The package also includes two electric field sensors including electric potential antennas adapted to couple to a water potential via a capacitive electrode having a conducting material and an electrically insulative layer formed of an insulating material. The capacitive electrode has a capacitance to the medium of greater than 1 mF. Preferably, the insulating material is a metal oxide.