Induction Sensor for Absorbent Articles
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Solution Overview
Problem
Existing absorbent articles, such as diapers and feminine hygiene products, face challenges in detecting wetness or fullness without increasing costs or altering their construction, especially when worn by young users who produce small amounts of body exudate, and existing sensors require direct contact with the body or have limited effectiveness.
Innovation Solution
A non-contact, passive induction-type sensor system using an induction coil and an electrical double-layer capacitor that measures impedance changes due to conductive liquids, allowing for remote detection of wetness without physical contact or additional cost, utilizing an exciter coil and sensor electronics to indicate the presence of body exudate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional resistive, capacitive, inductive or optical sensors are placed at insult locations to monitor wetness, then measurement precision is improved, but device complexity and manufacturing cost increase due to required electronic circuits and direct contact components
Solution Approach 1:
The patent replaces conventional mechanical/electrical contact sensors (resistive, capacitive, inductive sensors requiring direct contact and electronic circuits) with a magnetic field-based induction sensor system. The sensor coil detects changes in magnetic flux caused by conductive liquids, eliminating the need for direct electrical contact and complex circuitry while maintaining detection accuracy.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the sensor and the conductive liquid. Instead of direct contact between sensor electrodes and liquid, the magnetic field generated by the sensor coil interacts with the conductive liquid indirectly, enabling detection without physical contact and simplifying the device structure.
2Measurement precision
If sensors require direct contact with the body or conductive liquids to measure resistance, capacitance or impedance changes, then measurement precision is improved, but ease of operation and reliability decrease due to contamination risks and limited effectiveness in intimate contact products
Solution Approach 1:
The patent replaces direct-contact electrical measurement methods with non-contact magnetic field sensing. The sensor coil detects conductive liquids through magnetic flux changes without requiring physical contact, eliminating contamination risks and improving ease of operation for intimate hygiene products.
Solution Approach 2:
The magnetic field serves as an intermediary that enables detection of conductive liquids without direct contact between the sensor and the liquid or body surfaces, resolving the conflict between measurement precision and ease of operation/hygiene.
3Ease of operation
If alarm devices with visual or audible signals are added to assist parents in identifying wet conditions, then ease of operation is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces complex electronic alarm devices with a simple magnetic field-based sensor system that can be integrated into the absorbent article without adding significant complexity. The sensor coil and detection circuitry provide wetness indication through changes in magnetic flux, offering a simpler alternative to traditional visual or audible alarm systems.
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 and non-invasive monitoring of absorbent article status, providing meaningful signals to caregivers without altering the article's construction or increasing costs, with improved sensitivity and practicality for various absorbent products, including tampons.
Implementation Method 1
A noninvasive induction type sensor measures electrical conductivity at some depth within an absorbent article. A useful approach is an induction coil conductivity sensor, which can be attached to an appropriate target zone on or in the absorbent article. The induction coil, forming part of a resonant circuit, experiences an impedance change when conductive liquid is placed nearby.
Implementation Method 2
an electrical double-layer capacitor disposed on or in the article and in electrical communication with the sensor coil, wherein the capacitor is in fluid communication with the absorbent member
Data Source
AI summary
An absorbent article facilitating sensing the presence of a body exudate in the absorbent article includes an absorbent member; a sensor coil disposed on or in the article; and an electrical double-layer capacitor disposed on or in the article and in electrical communication with the sensor coil, wherein the capacitor is in fluid communication with the absorbent member. An absorbent article system also includes a detector circuit including an exciter coil configured for electromagnetic communication with the sensor coil, and sensor electronics configured to indicate the presence of a body exudate based on changes in the electromagnetic communication between the exciter coil and the sensor coil.