RFID Moisture Sensing With Shielded Reference Antennas
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Solution Overview
Problem
Existing moisture sensors face challenges in reliability, maintenance, and accuracy, particularly in moving environments, with wired sensors being cumbersome and wireless sensors limited by energy constraints and regulatory power usage, leading to false positives and manual, time-consuming leak detection processes.
Innovation Solution
A moisture detection system using dual sensor elements, one shielded and one unshielded, with a control module to analyze response signal differences, determining moisture presence by comparing signal strength and phase variations between the two elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wired sensors are used for moisture detection, then reliability and durability are improved, but device complexity and ease of operation deteriorate due to space requirements and maintenance burden
Solution Approach 1:
The patent replaces wired mechanical/electrical connection systems with wireless RFID-based sensor systems. The moisture sensors communicate wirelessly with readers, eliminating physical cables and connectors, thereby reducing installation complexity and maintenance burden while maintaining detection reliability
Solution Approach 2:
The wireless sensor system integrates multiple functions: moisture detection, wireless communication (RFID), and energy harvesting capabilities in a single platform, reducing the need for separate systems and lowering overall device complexity
2Ease of operation
If wireless sensors with active radios are used, then ease of installation is improved, but use of energy and cost increase due to battery requirements
Solution Approach 1:
The sensor system harvests energy from the ambient electromagnetic field and the RFID reader's signal to power its operations. The sensor autonomously generates the energy it needs for transmission and sensing without external battery power, eliminating maintenance and reducing energy supply requirements
Solution Approach 2:
The sensor operates in periodic transmission modes, remaining in low-power states between RFID reader interrogations. This periodic operation significantly reduces average energy consumption compared to continuous transmission while maintaining detection capabilities
3Ease of manufacture
If RFID technology is used for wireless moisture sensing, then cost and ease of installation are improved, but measurement precision deteriorates due to energy limitations affecting signal response
Solution Approach 1:
The patent introduces a liquid-absorbing material as an intermediary between the moisture environment and the RFID antenna. This material absorbs liquid and transports it to the antenna, amplifying the impedance change signal and improving measurement precision while maintaining low-cost RFID technology
Solution Approach 2:
The system monitors changes in RFID signal parameters (impedance, phase, amplitude) that occur when liquid is absorbed by the sensor material. By tracking these parameter variations, the system achieves precise moisture detection using standard RFID technology
4Measurement precision
If moisture sensors are read multiple times for calibration and detection, then measurement precision is improved, but loss of time increases due to false positives from environmental variations
Solution Approach 1:
The patent divides the sensor system into two independent sensor elements: one shielded from liquid and one unshielded. This segmentation allows separate measurement of environmental effects and moisture-specific effects, enabling faster and more accurate detection by comparing differential signals between the two elements
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
Provides a simple, fast, and cost-effective method for detecting moisture with reduced false positives, suitable for moving environments, enhancing operational efficiency and safety in assembly line applications.
Implementation Method 1
an element made of a liquid absorbing material, the liquid absorbing material being configured to absorb and drive liquid to the antenna of the first RFID label
Data Source
AI summary
A system for detecting moisture including: moisture sensors and a control module including a reader module, the control module is configured to: obtain a numerical value related to the feature of the selected response signal of the sensor element which is shielded against liquid; obtain a numerical value related to the feature of the selected response signal of the sensor element which is not shielded against liquid; determine a difference between the obtained numerical value related to the feature of the selected response signal from the sensor element which is shielded against liquid and the obtained numerical value related to the feature of the selected response signal from the sensor element which is not shielded against liquid; determine the detection of moisture if the determined difference is above or below a threshold. A method of detecting moisture is also provided.