Parallel Clock Salinity Sensor Using Capacitive Gap Measurement
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Solution Overview
Problem
Existing ocean salinity sensors face issues such as galvanic corrosion, marine fouling, high cost, bulkiness, and accuracy interference from nearby conductive objects, leading to unreliable and inaccurate measurements.
Innovation Solution
A salinity sensor utilizing a capacitive gap assembly with electrodes coated in hydrogel material, which allows for salinity measurement through displacement current without direct current passing between electrodes, reducing fouling and corrosion risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive electrodes are used to measure ocean salinity, then salinity measurement capability is achieved, but galvanic corrosion and marine fouling occur leading to unreliable measurements
Solution Approach 1:
The patent introduces an intermediary substance (electrolyte solution) between the electrodes to enable ionic conduction instead of direct electronic conduction through the electrodes. This mediator allows the measurement function while preventing direct electrochemical reactions between the electrodes and seawater, thereby eliminating galvanic corrosion and reducing marine fouling.
Solution Approach 2:
The patent replaces the traditional conductive measurement system with a capacitive measurement system. Instead of using direct electrical conduction through electrodes, the system uses displacement current through a dielectric barrier, substituting the measurement mechanism to avoid the harmful effects of direct electrode-seawater contact.
2Ease of operation
If inductive coupling between wire coils is used for salinity sensing, then non-contact measurement is achieved, but the sensors become bulky and rigid
Solution Approach 1:
The patent changes the operating parameters of the sensing system by using high-frequency AC signals and optimized capacitor geometries. This allows the sensor to achieve the desired measurement capability with significantly reduced physical dimensions compared to traditional inductive systems, making the sensor compact and flexible for deployment.
3Measurement precision
If inductive measurements are taken using unconfined magnetic fields, then measurement capability is achieved, but nearby conductive objects interfere with accuracy
Solution Approach 1:
The patent introduces a dielectric barrier as an intermediary between the sensing capacitors and the seawater. This barrier confines the electric field and prevents it from extending into the surrounding environment, thereby eliminating interference from nearby conductive objects such as ship hulls while maintaining the ability to measure salinity through the dielectric properties of the electrolyte solution.
4Volume of moving object
If traditional capacitive sensors are used, then compact size is achieved, but direct current causes fouling and corrosion
Solution Approach 1:
The patent replaces direct current (DC) with alternating current (AC) in the capacitive sensor system. This substitution eliminates the electrochemical reactions that cause fouling and corrosion, as AC prevents the accumulation of charges that would drive such reactions. The system maintains its compact capacitive design while using AC excitation to avoid the harmful effects of DC.
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 sensor provides accurate, reliable, and cost-effective salinity measurements with enhanced resistance to fouling and corrosion, while being compact and sensitive to small frequency shifts, supporting salinity sensitivity at 0.05 parts per thousand.
Implementation Method 1
a capacitive gap assembly that permits a fluid to flow into a gap between two electrodes of the capacitive gap assembly
Implementation Method 2
determine a salinity measurement of a fluid disposed in the gap between the two electrodes based on a displacement current between the electrodes
Implementation Method 3
The electrodes may be fully or partially coated with a hydrogel material
Data Source
AI summary
A sensor for measuring ocean water salinity is described. The sensor may include a measurement clock circuit, a control clock circuit, and a comparator circuit. The measurement clock circuit, having an output that varies with salinity of a fluid, may have a first circuit architecture that includes a capacitive gap assembly that permits a fluid to flow into a gap between two electrodes of the capacitive gap assembly. The control clock circuit, having an output that does not vary with salinity of the fluid, may have a second circuit architecture comprising a capacitor. The comparator circuit may be configured to compare the controlled clock output to the measured clock output over a duration of time to determine a salinity measurement of the fluid. The first circuit architecture may differ from the second circuit architecture in that an electrically connected position of the capacitive gap assembly within the first circuit architecture is the electrically connected position of the capacitor within the second circuit architecture.