Contactless Conductivity Sensor Using Induced Current Loops
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Solution Overview
Problem
Conductivity sensors face challenges in accurately measuring the composition of fluids, particularly in determining the type and concentration of solutes and solvents, due to issues like boundary charges, contact resistance, and chemical changes with traditional contact electrodes, and limitations with high-frequency usage in contactless sensors.
Innovation Solution
A contactless conductivity measuring system using a holder with an insulating material forming a fluid channel, an excitation device generating alternating current signals at varying frequencies, and conducting slabs to induce currents within the fluid, allowing for the formation of a current loop and enabling the detection of frequency-dependent conductivity, thereby determining the fluid's composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If contact electrodes are used for conductivity measurement, then the measurement setup is simple, but the measurements are confused by boundary charges, contact resistance, and chemical changes at the electrodes
Solution Approach 1:
The patent introduces an insulating holder as an intermediary component that physically separates the electrodes from the fluid while maintaining electrical connection. This mediator eliminates direct contact between electrodes and fluid, removing the harmful effects of boundary charges, contact resistance, and chemical changes at electrode surfaces, while preserving the simplicity of the measurement setup
2Reliability
If contactless sensors with coils are used, then chemical changes and electrode corrosion are avoided, but the use of high frequencies for excitation is seriously limited
Solution Approach 1:
The patent replaces the traditional coil-based electromagnetic excitation system with a capacitive coupling system using conducting slabs and insulating holders. This substitution eliminates the inductive effects that limit high-frequency operation in coil-based sensors, enabling reliable conductivity measurements across a broad frequency spectrum from low to high frequencies while maintaining the contactless advantage of avoiding chemical changes
3Device complexity
If single frequency conductivity measurement is performed, then the measurement is simple, but only the total ionic strength can be determined, not the composition in type of salts
Solution Approach 1:
The patent transforms the static single-frequency measurement into a dynamic multi-frequency measurement system. By sweeping through multiple frequencies and analyzing the frequency-dependent conductivity response, the system dynamically extracts detailed information about different ionic species and their concentrations, enabling identification of salt types and fluid composition while maintaining relatively simple measurement 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 effectively measures the composition of fluids by sensing voltage signals as a function of frequency, providing accurate information on the type and concentration of solutes and solvents, while minimizing interference and chemical changes, and enabling high-frequency usage.
Implementation Method 1
the electrical signal generator and the conducting slab are configured to induce between the connections elements a current through the conducting slab inducing an electrical current in the fluid inside the first part of the fluid channel
Implementation Method 2
a holder comprising a holder wall comprised of electrically insulating material, defining a fluid channel for holding fluid, wherein the holder is shaped to allow an electrical current induced in the fluid to form a current loop inside the fluid channel
Data Source
AI summary
The present disclosure relates to a conductivity measuring system of a fluid including a solvent and an ionic solute, comprising: —a holder comprising an isolated holder wall defining a fluid channel for holding fluid, wherein the holder is shaped to allow an electrical current induced in the fluid to form a current loop; —an excitation device configured to excite an electric field inside a first part of the fluid channel, the excitation device comprising an electrical signal generator configured to generate an alternating current signal and a conducting slab; —a sensing device arranged at a position remote from the first part of the fluid channel and configured to sense a voltage signal (V) resulting from the changing magnetic field resulting from the current generated inside the fluid by the excitation device.