Capacitive Sensor for Absorbent Article Wetness Detection
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Solution Overview
Problem
Conventional absorbent articles with conductive leads for wetness indicators face challenges in mass production and security screening, and pose issues with false positives in metal detectors and wearer safety.
Innovation Solution
A non-invasive capacitive sensor attached to the outer cover of absorbent articles detects changes in electrical capacitance to indicate the presence of body fluids without internal conductive elements, using a capacitive touch sensing system that emits signals when body fluids are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive leads are incorporated into absorbent articles for wetness detection, then wetness indicator functionality is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent removes conductive leads from the interior of the absorbent article and places the capacitive sensor on the exterior surface. This extraction eliminates the complexity of incorporating conductive elements into the article's interior while maintaining wetness detection functionality through non-contact capacitive sensing.
Solution Approach 2:
The patent replaces the mechanical/conductive lead system with a capacitive sensing system. Instead of using physical conductive threads or foils that require integration into the article, the system uses electrical capacitance measurement through a sensor placed on the exterior surface, simplifying the overall system.
2Reliability
If metallic conductive leads are used in absorbent articles, then wetness signaling is enabled, but false positives in metal detectors occur
Solution Approach 1:
The patent extracts metallic conductive elements from the absorbent article by using a non-contact capacitive sensor placed on the exterior surface. This eliminates metal content within the article that would trigger false positives in metal detectors while maintaining the ability to detect wetness through capacitance changes.
Solution Approach 2:
The patent introduces an intermediary sensing mechanism (capacitive sensor measuring electrical field changes) that does not require direct contact with or incorporation of metallic elements into the article. The sensor detects wetness indirectly through changes in capacitance, avoiding the need for metallic conductive leads.
3Reliability
If conductive leads are placed in absorbent articles, then wetness detection is achieved, but production speed is reduced
Solution Approach 1:
The patent extracts the wetness detection function from the article's interior structure and places it on the exterior surface as a separate sensor component. This allows the article to be manufactured at high speed without the complexity of incorporating conductive leads, while the sensor is added separately to provide wetness detection capability.
4Reliability
If conductive elements are added to absorbent articles, then wetness signaling capability is improved, but article cost increases
Solution Approach 1:
The patent removes expensive metallic conductive leads from the article interior and replaces them with a simpler capacitive sensor system placed on the exterior. This extraction and replacement reduces material costs and manufacturing complexity while maintaining wetness detection capability.
Solution Approach 2:
The patent substitutes the expensive mechanical/conductive lead system with a more cost-effective capacitive sensing system. The sensor measures electrical capacitance changes without requiring metallic elements within the article, reducing material costs while providing reliable wetness detection.
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 simplifies the incorporation of wetness indicators into absorbent articles, avoids false positives in security screening, and ensures safe passage through metal detectors while providing effective detection of body fluids without increasing production costs.
Implementation Method 1
A non-invasive sensor measures electrical capacitance at some depth within an absorbent article
Data Source
AI summary
Signaling systems are disclosed that indicate a change in an absorbent article, such as the presence of a body fluid. The various different signaling systems disclosed do not include any conductive elements contained on the interior of the article as were required in the past. Instead, the changes are monitored from the outer cover of the article. In one aspect, for instance, a signaling device is provided for sensing and indicating the presence of a body exudate in an absorbent article, the device including a housing and a capacitive sensor disposed within the housing, the capacitive sensor adapted to sense a change in capacitance due to an insult to the absorbent article. The signaling device can include an attachment mechanism for removably attaching the housing to the absorbent article.