Wireless Corrosion Sensor Using Inductive Resonance Shifts
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Solution Overview
Problem
Conventional corrosion detection methods, such as eddy current testing and remote RF sensing, are limited in their ability to accurately monitor corrosion beneath the surface or in complex environments, requiring time-consuming and unreliable techniques.
Innovation Solution
A corrosion sensor with an inductive element featuring a first and second inductive loop connected by a sacrificial corroding link, where the loss of the link changes the resonant frequency and Q factor, allowing for discrete measurement of corrosion through changes in the sensor's inductance and resonant behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional eddy current testing is used to detect corrosion, then surface breaks and near surface cracking can be detected, but the testing process becomes time-consuming and difficult to read reliably
Solution Approach 1:
The patent replaces conventional mechanical eddy current testing with a wireless resonant sensor system that uses electromagnetic resonance at specific frequencies (e.g., 2.45 GHz) to detect corrosion. The sensor incorporates a corroding element that changes the resonant frequency as corrosion progresses, enabling reliable detection without time-consuming manual interpretation
Solution Approach 2:
The invention utilizes changes in resonant frequency as a parameter to indicate corrosion progression. As the corroding element degrades, it alters the electrical characteristics of the sensor, causing measurable shifts in resonant frequency that directly correlate with corrosion severity, providing both reliability and speed
2Measurement precision
If remote RF sensing of L-C circuits is used with pancake metal coils, then resonant frequency can be measured, but the fringing capacitance reaches out into the coating and is influenced by dielectric properties making detection complex
Solution Approach 1:
The patent extracts and eliminates the problematic fringing capacitance element from the sensor design. By using a different resonant circuit configuration that does not rely on fringing fields extending into the coating, the invention achieves precise resonant frequency measurement without the complexity of dealing with dielectric property variations in the coating
Solution Approach 2:
The invention uses a simplified resonant circuit model that copies only the essential measurement function without the problematic fringing capacitance. The sensor design replicates the resonant frequency measurement capability while eliminating the complex interaction with coating dielectric properties
3Loss of information
If wireless devices powered externally are used to interrogate sensors, then resonant frequency can be determined, but the system requires external readers and becomes more complex
Solution Approach 1:
The patent implements a self-powered wireless sensor that harvests energy from the interrogating RF field itself. The sensor contains no batteries or external power requirements, instead using electromagnetic induction to power its resonant circuit and transmit data back to the reader, eliminating the need for separate power management systems
Solution Approach 2:
The sensor design combines multiple functions into a single device: it serves as both the resonant element for detection and the powered transmitter for data communication. The same RF field that interrogates the sensor also powers it, creating a universal system that reduces overall complexity
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
This approach enables straightforward and reliable detection of corrosion by measuring shifts in resonant frequency and Q factor, providing localized and timely monitoring of corrosion without the need for complex capacitive or resistive elements, enhancing sensitivity and accuracy.
Implementation Method 1
an alternating current in the coil yields a changing magnetic field, which interacts with the test object and induces eddy currents in it
Implementation Method 2
The alternating current in the coil yields a changing magnetic field, which interacts with the test object and induces eddy currents in it. Variations in the phase and magnitude of these eddy currents can be monitored
Data Source
AI summary
A sensor, method, and system for sensing corrosion. The sensor may be used to monitor the integrity of structural elements. The sensor, method, and system utilizing an inductive element formed on the substrate and having a first inductive loop and a second inductive loop. The sensor also includes a sensing element electrically connecting one end of the first inductive loop to an opposing end of the second inductive loop. Prior to dissolution of the sensing element, an inductance of the inductive element comprises a first inductance set by the first predetermined number of turns of the inductor coil having a first resonant frequency. After dissolution of the sensing element, the inductance of the inductive element comprises a second inductance reduced from the first inductance.