Capacitive Diaper Content Sensing With Reusable Outer Coupling
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Solution Overview
Problem
Existing diaper sensing technologies face challenges with expensive silver-based conductive inks that pose environmental risks and carbon-based inks that are less conductive, making inductive or RF coupling difficult, while direct galvanic connections are cumbersome and prone to errors.
Innovation Solution
A system comprising a diaper with an inner circuitry layer using carbon-based conductive ink for tracks and capacitor plates, coupled capacitively with an outer reusable layer, allowing for passive content sensing without galvanic connections, using resistive and capacitive coupling for signal transformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver-based conductive inks are used, then conductivity is improved, but cost and environmental risk increase
Solution Approach 1:
The patent uses carbon-based conductive ink instead of silver-based conductive ink for the disposable inner circuitry layer. Carbon-based ink is cheaper and environmentally friendly, and since the inner layer is disposable, the lower conductivity is acceptable as it only needs to function during the diaper's use period.
Solution Approach 2:
The patent introduces an outer reusable circuitry layer that acts as an intermediary. This outer layer uses high-conductivity materials and handles the high-conductivity requirements for inductive or RF coupling, while the inner disposable layer uses low-cost carbon-based ink.
2Ease of manufacture
If carbon-based conductive inks are used, then cost and environmental friendliness are improved, but conductivity deteriorates
Solution Approach 1:
The patent introduces an outer reusable circuitry layer that acts as an intermediary. This outer layer uses high-conductivity materials and handles the high-conductivity requirements for inductive or RF coupling, while the inner disposable layer uses low-cost carbon-based ink.
Solution Approach 2:
The circuitry is divided into two separate layers: an inner disposable layer with carbon-based ink for basic functionality, and an outer reusable layer with high-conductivity materials for signal coupling. This segmentation allows each layer to be optimized for its specific function.
3Reliability
If direct galvanic connection is used, then coupling is achieved, but device complexity and error proneness increase
Solution Approach 1:
The patent uses capacitive coupling as an intermediary method between the inner and outer circuitry layers. This eliminates the need for direct physical connections through probes or clips, reducing complexity and error proneness while maintaining reliable signal transfer.
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 effective diaper content sensing with low-cost, environmentally friendly materials, avoiding direct connections and reducing signal loss, while minimizing external disturbances for accurate moisture detection.
Implementation Method 1
The coupling capacitors are formed by the inner plates within the diaper and by the outer plates of the outer coupling layer provided on the outside of the diaper wherein the diaper material between these layers serves as dielectric.
Implementation Method 2
tracks arranged to provide a resistive coupling between the inner capacitor plates dependent on the diaper content
Data Source
AI summary
A system for sensing diaper content includes a diaper, an outer coupling layer and a sensing circuitry. The diaper has a circuitry layer having inner input capacitor plates, tracks arranged to provide a resistive coupling between the inner capacitor plates dependent on the content, and inner output capacitor plates in galvanic contact with the respective inner input capacitor plates. The outer coupling layer contains outer input- and output capacitor plates arranged to form respective input- and output capacitors with the inner input- and output capacitor plates in the diaper when the outer coupling layer is provided onto the outside of the diaper. The sensing circuitry is arranged to apply an input signal onto the outer input capacitor plates, and to measure an output signal from the outer output capacitor plates resulting from the input signal and the resistive coupling thereby sensing the content.