Variable Capacitor Wetness Sensor for Absorbent Articles
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Solution Overview
Problem
Conventional disposable absorbent articles, such as diapers and sanitary napkins, lack effective dynamic wetness detection capabilities, unable to accurately monitor the absorption capacity and excretion conditions, leading to frequent replacements or potential leakage issues.
Innovation Solution
An electronic wetness-sensing absorbent article is developed, featuring a flexible waterproof thin film with insulated electrodes and a water-permeable braided fabric layer, forming a non-polar variable electrolytic capacitor, which detects capacitance changes to provide comprehensive wetness state information, including liquid absorption and saturation levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional wetness detection technology (short-circuiting two electrodes through urine) is used, then the detection simplicity is improved, but the measurement precision is worsened because it can only detect whether urination has occurred instead of detecting the degree of wetness
Solution Approach 1:
The patent changes the detection parameter from binary electrode short-circuiting to continuous capacitance value measurement. The variable electrolytic capacitor measures the capacitance value that changes with liquid content, enabling quantification of wetness degree rather than simple wet/dry detection. This resolves the contradiction by maintaining operational simplicity while achieving precise measurement through parameter transformation.
Solution Approach 2:
The patent replaces the mechanical/conductive detection method (electrode short-circuiting) with an electrical field-based method (capacitance measurement). The variable electrolytic capacitor uses electrical field interaction with the liquid electrolyte to detect wetness, substituting the direct conductive contact method and enabling more precise measurement while keeping the system simple.
2Device complexity
If no wetness detection is implemented, then the device complexity is reduced, but the loss of information is worsened because dynamic information about urination process and absorption capacity cannot be provided
Solution Approach 1:
The waterproof thin film serves multiple functions: it acts as both the waterproof barrier and the dielectric layer of the variable electrolytic capacitor. The liquid absorbent layer serves dual purposes of absorbing urine and providing the electrolyte for capacitance measurement. This multi-functionality reduces device complexity while enabling comprehensive wetness information detection.
Solution Approach 2:
The patent uses the urine itself as the electrolyte in the variable electrolytic capacitor, eliminating the need for separate detection fluids or complex sensor systems. The absorbent layer naturally provides the liquid medium needed for capacitance measurement, making the system self-sufficient and reducing overall complexity while preventing information loss.
3Reliability
If frequent replacement of absorbent articles is performed, then the reliability is improved by preventing leakage, but the loss of substance is worsened due to waste
Solution Approach 1:
The variable electrolytic capacitor provides real-time feedback on the wetness state and absorption capacity through capacitance value changes. This feedback enables users to monitor the absorbent article's status dynamically and replace it at the optimal time, preventing both premature replacement (waste) and late replacement (leakage), thus resolving the contradiction between reliability and waste reduction.
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 enables dynamic and accurate monitoring of wetness states, determining when the absorbent article needs replacement, thereby reducing waste and preventing leakage by providing real-time absorption capacity data.
Implementation Method 1
the flexible waterproof thin film, the flexible electrodes, and the liquid contained in the absorbent layer form a non-polar variable electrolytic capacitor, in which the flexible electrodes serve as electrodes of the electrolytic capacitor, the flexible waterproof thin film serves as a dielectric of the electrolytic capacitor, the liquid serves as an electrolyte of the electrolytic capacitor, and the wetness state of the electronic wetness-sensing absorbent article is obtained by detecting the capacitance value of the variable electrolytic capacitor
Implementation Method 2
the liquid contained in the absorbent layer form a non-polar variable electrolytic capacitor, in which the liquid serves as an electrolyte of the electrolytic capacitor
Implementation Method 3
an absorbent layer disposed on the other surface of the flexible waterproof thin film, located between the flexible waterproof thin film and the water-permeable braided fabric layer, and adapted to absorb a liquid entering from the water-permeable braided fabric layer
Data Source
AI summary
The present application relates to an electronic wetness-sensing absorbent article and related methods. The electronic wetness-sensing absorbent article includes a flexible waterproof thin film; at least two mutually separated and insulated flexible electrodes disposed on one surface of the flexible waterproof thin film; a water-permeable braided fabric layer; and an absorbent layer disposed on the other surface of the flexible waterproof thin film, located between the flexible waterproof thin film and the water-permeable braided fabric layer, and adapted to absorb a liquid entering from the water-permeable braided fabric layer. The flexible waterproof thin film, the flexible electrodes, and the liquid contained in the absorbent layer form a non-polar variable electrolytic capacitor. The wetness state of the electronic wetness-sensing absorbent article is obtained by detecting the capacitance value of the variable electrolytic capacitor and change thereof.