RF Wetness Sensor with Dissolving Substrate for Remote Detection
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Solution Overview
Problem
Current wetness sensors for diapers and other applications are not widely adopted due to limitations in detecting wetness without physical checks, posing health risks and inefficiencies in monitoring, especially for adult patients who cannot communicate their wetness status, and are difficult to integrate into various materials and structures for leakage detection.
Innovation Solution
Development of a family of wetness sensors with a self-supporting substrate and an electrically conductive trace forming a tuned RF circuit that degrades upon contact with target fluids, allowing remote detection through a drastic change in impedance or resistance, compatible with low-cost manufacturing and adaptable for use in diapers, construction materials, and other applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical checks are performed to monitor wetness status, then monitoring reliability is improved, but time consumption and health risks increase
Solution Approach 1:
The patent replaces the mechanical physical inspection system with an electromagnetic field-based sensing system. The tuned RF circuit responds to fluid contact through electromagnetic interactions, allowing remote detection without physical contact. This substitution eliminates the need for caregivers to physically handle patients while maintaining monitoring reliability through electromagnetic field-based wetness detection.
Solution Approach 2:
The patent introduces an intermediary sensing system consisting of the substrate and tuned RF circuit that mediates between the fluid and the detection system. The substrate acts as a transducer, converting fluid contact into electrical signal changes that can be remotely detected. This intermediary enables accurate monitoring without requiring direct physical intervention.
2Reliability
If physical checks are performed to monitor wetness status, then monitoring reliability is improved, but health risks to staff increase
Solution Approach 1:
The patent replaces the mechanical physical inspection system with an electromagnetic field-based sensing system. The tuned RF circuit responds to fluid contact through electromagnetic interactions, allowing remote detection without physical contact. This substitution eliminates the need for caregivers to physically handle patients while maintaining monitoring reliability through electromagnetic field-based wetness detection.
Solution Approach 2:
The sensing system performs self-monitoring through the physiological changes that occur during wetness. The substrate and RF circuit automatically detect fluid contact through changes in electrical properties, eliminating the need for external physical intervention. The system serves itself by utilizing the natural electromagnetic responses to fluid presence.
3Measurement precision
If substrate degrades upon fluid contact to enable detection, then detection sensitivity is improved, but sensor durability worsens
Solution Approach 1:
The patent employs dynamic material properties where the substrate transitions from a stable, intact state to a degraded state upon fluid contact. This dynamic behavior enables the substrate to serve dual purposes: maintaining structural integrity during normal operation and undergoing controlled degradation for detection when fluid is present. The tuned RF circuit detects these dynamic changes in real-time.
Solution Approach 2:
The patent utilizes parameter changes in the substrate's physical and electrical properties in response to fluid contact. The substrate exhibits changes in conductivity, impedance, or resonant frequency when exposed to fluid, allowing the RF circuit to detect wetness status. These parameter changes provide a reliable signal for detection while the substrate maintains durability under normal dry conditions.
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 remote and efficient detection of wetness without physical checks, reducing health risks and monitoring time, and can be integrated into various materials and structures for effective leakage detection, improving safety and efficiency in healthcare and construction settings.
Implementation Method 1
The substrate is adapted to dissolve, swell, or otherwise degrade when contacted by a target fluid. Such degradation of the substrate produces a drastic change in the operation of the RF circuit, which can be interpreted by a remote reader or interrogation device as a 'wet' condition.
Implementation Method 2
The substrate is adapted to dissolve, swell, or otherwise degrade when contacted by a target fluid. Such degradation of the substrate produces a drastic change in the operation of the RF circuit, which can be interpreted by a remote reader or interrogation device as a 'wet' condition.
Implementation Method 3
The contact by the target fluid may change the impedance or resistance of the RF circuit by at least a factor of 5, 10, 100, or 1000.
Implementation Method 4
The contact by the target fluid may cause the electrically conductive trace to disintegrate so as to provide the RF circuit with an open circuit. The contact by the target fluid may substantially render the RF circuit inoperative.
Data Source
AI summary
A wetness sensor includes a self-supporting substrate and an electrically conductive trace carried by the substrate. The trace is patterned to provide at least a portion of a tuned RF circuit, which may be disposed on only one side of the substrate and characterized by an impedance or resistance. The trace is not self-supporting. The substrate is adapted to dissolve, swell, or otherwise degrade when contacted by a target fluid. Such degradation produces a drastic change in the operation of the RF circuit, which can be interpreted by a remote reader as a “wet” condition. Contact of the substrate by the target fluid may change the impedance or resistance of the RF circuit by at least a factor of 5, 10, 100, or 1000, and/or may cause the trace to disintegrate so as to provide the RF circuit with an open circuit, and/or may substantially render the RF circuit inoperative.