Moisture-Absorbing Sensor With Shape-Stable Capacitance Detection
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Solution Overview
Problem
Existing humidity monitoring systems are costly, require power sources, and lack the ability to freely set humidity detection thresholds, with materials losing shape after moisture absorption and requiring separate absorption materials.
Innovation Solution
A moisture absorbing sensor with a hygroscopic material that maintains shape and electrical characteristics, allowing for adjustable humidity detection thresholds by controlling thickness and material type, and includes electrodes to measure electrostatic capacitance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional humidity sensor system is used, then humidity monitoring can be performed, but the system becomes complicated and costly
Solution Approach 1:
The patent extracts the essential humidity sensing function from the complex conventional system by using a simple RFID tag structure. The humidity sensor, circuit, and processing components are removed, leaving only the essential elements (antenna, substrate with humidity-sensitive material) needed to perform humidity monitoring through RFID communication.
Solution Approach 2:
The humidity-sensitive material on the RFID tag substrate automatically responds to humidity changes by altering its electrical characteristics (capacitance or resistance). This self-changing property eliminates the need for external power sources, complex sensing circuits, or active processing components, allowing the tag to autonomously indicate humidity levels.
2Duration of action of moving object
If a battery-powered humidity sensor is used, then continuous monitoring is possible, but periodic battery replacement is required
Solution Approach 1:
The RFID tag utilizes passive components (antenna, substrate, humidity-sensitive material) that derive power from the RFID reader's electromagnetic field. This eliminates batteries and all associated maintenance requirements while enabling continuous monitoring throughout the tag's operational life.
3Measurement precision
If a deliquescent material is used for moisture detection, then humidity threshold can be detected, but the material loses its shape after moisture absorption
Solution Approach 1:
The patent uses a hygroscopic material with porous structure that absorbs moisture while maintaining its solid form. The porous structure allows water molecules to be absorbed and retained within the material matrix, causing measurable changes in electrical characteristics without the material liquefying or losing its shape.
4Measurement precision
If the thickness of hygroscopic material is increased, then sensitivity to humidity increases, but the response time becomes slower
Solution Approach 1:
The patent optimizes the thickness of the hygroscopic material layer to achieve the desired balance between sensitivity and response time. By controlling the local property (thickness) of the material, the system achieves sufficient humidity sensitivity while maintaining acceptable response characteristics.
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
Enables accurate, power-free humidity monitoring with adjustable thresholds and shape retention, facilitating easy threshold setting and high sensitivity across various humidity levels.
Implementation Method 1
a hygroscopic material configured to maintain a shape before and after moisture absorption
Implementation Method 2
An electrical characteristic of a circuit formed by the electrode and the hygroscopic material changes according to a moisture absorption amount
Data Source
AI summary
A moisture absorbing sensor is provided that includes a hygroscopic material that maintains a shape before and after moisture absorption and maintains a hygroscopic state for a predetermined time or more after moisture absorption; and an electrode disposed in the hygroscopic material. Moreover, an electrical characteristic of a circuit formed by the electrode and the hygroscopic material changes according to a moisture absorption amount of the hygroscopic material.