Wireless SAW Corrosion Sensor with Sacrificial Links
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Solution Overview
Problem
Existing corrosion sensors for concrete structures are invasive, requiring electrical wires and frequent recalibration, or they use electrochemical devices that are not suitable for long-term durability and non-invasive monitoring.
Innovation Solution
A wireless surface acoustic wave (SAW) sensor system with a modified dipole antenna incorporating sacrificial corrosive links made of similar steel grade material to the concrete rebars, which corrode at the same rate, disrupting the RF signal path to indicate corrosion, allowing for non-invasive and durable corrosion monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If invasive corrosion sensors with electrical wires are used, then corrosion monitoring capability is achieved, but the structure is damaged and frequent recalibration is required
Solution Approach 1:
The patent replaces invasive mechanical/electrical sensing systems with a wireless surface acoustic wave (SAW) sensor system. The SAW sensor uses acoustic waves propagating on the concrete surface to detect corrosion-induced changes in impedance, eliminating the need for electrical wires penetrating the structure. This substitution of mechanical/electrical contact with acoustic wave propagation resolves the contradiction by maintaining monitoring capability while avoiding structural damage.
Solution Approach 2:
The patent introduces an intermediary mechanism - the surface acoustic wave - that mediates between the corrosion condition and the sensing system. Instead of direct electrical contact with the rebar, the SAW propagates on the concrete surface and detects corrosion through changes in electrical impedance of the antenna system, providing non-invasive monitoring while maintaining sensitivity to corrosion conditions.
2Reliability
If electrochemical devices are used for corrosion monitoring, then corrosion detection is achieved, but long-term durability and non-invasive monitoring are compromised
Solution Approach 1:
The patent replaces electrochemical sensing mechanisms with a surface acoustic wave-based electrical impedance sensing system. The SAW sensor detects corrosion through changes in the electrical impedance of the antenna as corrosion products alter the electromagnetic field distribution, rather than through electrochemical reactions. This substitution provides superior long-term durability as the sensor itself does not undergo electrochemical degradation.
Solution Approach 2:
The SAW sensor system is fully wireless and requires no external power supply or calibration adjustments during operation. The sensor autonomously detects corrosion through passive measurement of impedance changes, eliminating the need for frequent human intervention for recalibration or maintenance, thereby achieving superior long-term durability and reliability.
3Measurement precision
If frequent recalibration is performed on invasive sensors, then measurement accuracy is maintained, but operational complexity and maintenance requirements increase
Solution Approach 1:
The SAW sensor system is designed to be inherently stable and calibration-free for long-term operation. The wireless acoustic wave sensor maintains measurement precision through its stable resonant frequency characteristics and passive measurement approach, eliminating the need for frequent recalibration. The system serves itself by maintaining accurate corrosion measurements without human intervention for extended periods.
Solution Approach 2:
The patent enables continuous, uninterrupted corrosion monitoring without periodic shutdowns for recalibration. The SAW sensor continuously tracks impedance changes as corrosion progresses, providing uninterrupted measurement capability that maintains precision over the entire service life of the structure without operational interruptions for maintenance.
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 provides a non-invasive and rugged means to monitor corrosion in concrete structures, avoiding damage and the need for frequent recalibration, with the sacrificial links effectively indicating the degree of corrosion through signal degradation.
Implementation Method 1
A surface acoustic wave (SAW) sensor system includes a transducer that receives an RF signal and converts the RF signal into a SAW
Implementation Method 2
incorporating sacrificial corrosive links made of similar steel grade material to the concrete rebars, which corrode at the same rate
Data Source
AI summary
A SAW sensor disposed in on a material. The sensor comprises an antenna having a sacrificial link in at least one antenna element, wherein the sacrificial link is exposed to degrading elements within or on a surface of the material, a SAW transducer responsive to an interrogation signal for generating an incident acoustic wave, a reflector responsive to the incident SAW for creating a reflected SAW, the reflected SAW received by the transducer, the transducer for creating a response signal responsive to the reflected SAW, and the response signal transmitted from the antenna, characteristics of the response signal dependent on a condition of the sacrificial link.