Slotted Sensor for Diaper Moisture Detection
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Solution Overview
Problem
Existing diaper moisture sensors often generate false alarms due to detecting moisture retained by the absorbent layer after urine absorption, and require structural modifications to ordinary diapers, leading to high manufacturing costs and inconvenience.
Innovation Solution
A disposable moisture sensor strip with electrodes on its bottom surface, attached to the top permeable layer of the diaper via a support structure that maintains a gap to prevent contact with retained moisture, allowing for accurate detection of urine without false alarms and enabling reuse of the alerting device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor strip is placed in direct contact with the absorbent layer to detect moisture, then the detection sensitivity is improved, but false alarms occur due to detecting retained moisture after urine absorption
Solution Approach 1:
The sensor strip is divided into multiple sensing zones with electrodes arranged in segments along its length. Each segment can independently detect moisture at specific locations, allowing the system to distinguish between retained moisture (which remains in one area) and fresh urine flow (which moves across multiple zones), thereby reducing false alarms while maintaining detection sensitivity.
Solution Approach 2:
A hydrophobic barrier layer is introduced between the sensor strip and the absorbent layer. This intermediary layer allows urine to reach the electrodes while preventing direct contact with retained moisture in the absorbent core, enabling accurate detection of fresh urine without triggering false alarms from absorbed moisture.
2Ease of manufacture
If the sensor strip is made detachable from the alerting device, then manufacturing cost is reduced and device reuse is enabled, but connection reliability between sensor and alerting device may be compromised
Solution Approach 1:
The system is segmented into two independent parts: a disposable sensor strip and a reusable alerting device. The sensor strip contains all necessary sensing elements and can be manufactured separately at lower cost, while the expensive alerting device with battery and processing electronics can be reused across multiple sensor strips, reducing overall manufacturing cost while maintaining functional reliability.
Solution Approach 2:
The sensor strip is pre-assembled with electrodes, conductive traces, and adhesive layers during manufacturing. This preliminary preparation ensures that when the sensor strip is attached to the alerting device, the electrical and mechanical connections are already optimized, maintaining connection reliability despite the detachable design.
3Area of stationary object
If the sensor strip covers a large detection area to monitor the entire diaper, then detection coverage is improved, but the sensor strip becomes more complex and expensive
Solution Approach 1:
The large detection area is divided into multiple smaller sensing zones with discrete electrode pairs arranged along the length of the sensor strip. Each zone is relatively simple in structure, but collectively they provide comprehensive coverage of the entire diaper area, reducing the complexity of individual components while maintaining overall detection coverage.
Solution Approach 2:
The sensor strip is designed with a universal structure that can detect moisture at multiple locations simultaneously. The same basic electrode pattern is repeated across different zones, allowing the sensor to monitor the entire diaper area using a standardized, cost-effective design rather than requiring complex custom sensors for each zone.
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
The solution effectively prevents false alarms by detecting only fresh urine and allows the sensor strip to be used with standard diapers, reducing manufacturing costs and improving user convenience.
Implementation Method 1
The sensing elements can detect moisture when body fluid is excreted by a wearer of the diaper
Implementation Method 2
the support structure causes a gap to be maintained between the sensor strip and the absorbent layer, such that capillary action does not cause the absorbed moisture to come in contact with the sensor strip
Data Source
AI summary
A system for sensing wetness in an ordinary diaper includes a disposable sensor unit which has a sensor strip and support structure. The sensor strip has electrical circuit with conductive elements as wetness sensors printed on the bottom surface of the strip, wherein a closed electrical circuit is formed when an amount of body fluid is present that subsequently triggers an alerting device. The support structure has multiple slots cut out on it to expose conductive elements to urine and also keeps the conductive elements at a specific height from the diaper's padding such that urine content retained by a soaked diaper do not raise alarms.