Cementitious Panel Moisture Sensor with Passive RFID
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Solution Overview
Problem
Current non-destructive roof moisture evaluation techniques indirectly detect moisture by assessing properties that may be caused by water presence, rather than directly measuring sub-surface moisture levels, lacking a reliable method for identifying leaks and unwanted moisture in structural assemblies.
Innovation Solution
A cementitious panel with a moisture sensor, comprising a passive RFID tag integrated into the panel, which transmits moisture values to an RFID reader for analysis, enabling direct measurement and detection of moisture levels within structural assemblies, such as roofs, using a non-destructive and contactless method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If indirect detection methods (electric capacitance, infrared thermography, nuclear hydrogen detection) are used to assess moisture, then the roof assembly properties can be evaluated, but the measurement precision of actual moisture levels is insufficient
Solution Approach 1:
The patent replaces indirect physical assessment methods with a direct chemical/electrical detection system. A moisture sensor containing a hydrophilic material and pH-sensitive indicator is embedded in the cementitious panel, which directly detects moisture presence through chemical interaction (pH change) rather than indirect physical property assessment, thereby improving measurement precision and reliability
Solution Approach 2:
The patent introduces a moisture sensor as an intermediary element embedded within the cementitious panel. This sensor acts as a mediator that directly interacts with moisture through its hydrophilic material and pH-sensitive indicator, converting moisture presence into a detectable electrical signal, thus enabling reliable direct moisture detection without compromising the structural integrity
2Object-affected harmful factors
If non-destructive evaluation techniques are used, then the structural assembly remains intact, but the ability to directly determine moisture presence is limited
Solution Approach 1:
The patent embeds the moisture sensor within the cementitious panel during manufacturing, creating a nested structure where the sensor is integrated into the panel's matrix. This allows direct sub-surface moisture detection without requiring destructive exposure or separate attachment, maintaining structural integrity while enabling precise moisture measurement
Solution Approach 2:
The patent replaces mechanical/destructive exposure methods with an embedded electrical/chemical sensing system. The moisture sensor, containing hydrophilic material and pH-sensitive indicator, directly detects sub-surface moisture through chemical interaction, eliminating the need for destructive sampling while achieving high measurement precision
3Device complexity
If indirect detection methods are employed, then the detection system complexity is reduced, but the loss of information about actual moisture levels increases
Solution Approach 1:
The moisture sensor is designed to be self-powered through its piezoelectric element, which generates electrical energy from ambient pressure or temperature changes. This eliminates the need for external power sources or complex wiring, reducing device complexity while the pH-sensitive indicator continuously provides accurate moisture level information through direct chemical interaction
Solution Approach 2:
The patent replaces complex indirect detection systems with a simple embedded sensor that uses chemical interaction (pH change) and piezoelectric effects to directly measure moisture. This substitution of mechanical/direct physical methods with chemical-electrical sensing achieves high information accuracy while maintaining simple device structure
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 solution provides a quick and accurate means to measure sub-surface moisture levels, identifying problem areas and issuing alerts when moisture exceeds predetermined thresholds, enhancing the detection of leaks and moisture issues in structural assemblies without damaging the structure.
Implementation Method 1
The passive RFID tag includes an antenna adapted to receive and transmit a signal
Implementation Method 2
An electric capacitance roof survey measures differences in a dielectric constant of a roof assembly, which can change in the presence of moisture
Data Source
AI summary
Embodiments of a system and a method for detecting moisture within a structure can use a cementitious panel including a moisture sensor. The moisture sensor can comprise a moisture-sensing, passive RFID tag. A reader can be used to periodically interrogate the RFID moisture-sensing tag to determine whether the RFID moisture-sensing tag has been subjected to moisture. Systems and methods for detecting moisture within a structure can use at least one such cementitious panel in a structural assembly, such as a roof assembly, for example, to help detect a leak in the roof assembly through periodic monitoring of the installed cementitious panel(s).