Incontinence Detection Using Through-Thickness Resistance Measurement
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Solution Overview
Problem
Incontinence detection devices face challenges with inaccurate liquid detection due to varying trace spacing, leading to false negatives or positives, and are not well-suited for detecting liquid penetration depth.
Innovation Solution
A system with a layer of material having uniformly distributed electrically resistive elements, an RFID tag, and a processor that responds to deviations in electrical resistance between dry and wet states, allowing for accurate detection of liquid presence and penetration depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If trace spacing is increased to reduce false positives, then detection accuracy improves, but false negatives increase
Solution Approach 1:
The pad is divided into multiple discrete trace pairs, each with its own RFID tag and resistance measurement circuit. This segmentation allows independent monitoring of different regions, so that liquid detection can be localized to specific areas rather than requiring uniform detection across the entire pad surface.
Solution Approach 2:
The invention transitions from in-plane trace spacing considerations to through-thickness resistance measurement. By measuring resistance between the top and bottom surfaces of the pad rather than between laterally separated traces, the system detects liquid penetration depth in the vertical dimension, eliminating the trade-off between trace spacing and detection accuracy.
2Measurement precision
If trace spacing is decreased to detect smaller liquid volumes, then sensitivity improves, but false positives increase
Solution Approach 1:
Multiple discrete trace pairs are distributed throughout the pad, each capable of independent liquid detection. This allows the system to monitor several locations simultaneously, improving overall sensitivity without requiring closely spaced traces in any single location.
Solution Approach 2:
The measurement approach shifts from lateral trace spacing to vertical penetration depth measurement. Liquid must penetrate through the entire pad thickness to create a conductive path, providing a clear threshold that distinguishes true incontinence events from minor surface contamination or perspiration.
3Ease of manufacture
If uniform trace spacing is used across the pad, then manufacturing simplicity improves, but detection accuracy varies at different locations
Solution Approach 1:
The pad is divided into multiple independent sensing zones, each with its own trace pair and RFID tag. This segmentation allows uniform manufacturing processes to be applied to each module while maintaining consistent detection performance across all locations through modular assembly.
Solution Approach 2:
By measuring resistance through the pad thickness rather than across lateral distances, the system eliminates location-dependent variations in detection accuracy. The vertical measurement path is consistent regardless of horizontal position on the pad.
4Device complexity
If traditional trace-based detection is used, then device complexity remains low, but liquid penetration depth cannot be detected
Solution Approach 1:
The invention introduces through-thickness resistance measurement capability while maintaining compatibility with existing RFID tag technology. Leads extend from the RFID tag through the pad structure to contact the bottom surface, enabling vertical resistance measurement without requiring completely new detection electronics.
Solution Approach 2:
The pad material itself serves as the intermediary that translates liquid penetration depth into measurable resistance changes. As liquid penetrates through the absorbent layers, it creates a conductive path that reduces resistance between the top and bottom surfaces, providing depth information through the pad's inherent structure.
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 system provides improved accuracy in detecting incontinence events by ensuring consistent resistance measurements across the pad, reducing false positives and negatives, and effectively distinguishing between different liquids and their penetration depths.
Implementation Method 1
Each layer has a baseline electrical resistance and an actual electrical resistance... The tag is responsive to deviations of the actual resistance from the baseline resistance... The wet electrical resistance is less than the dry electrical resistance
Data Source
AI summary
An incontinence detector includes a layer of material having uniformly distributed electrically resistive elements which impart a baseline electrical resistance to the layer. The layer also has an actual electrical resistance. The detector also includes an RFID tag having a first and second leads which extend into the material without contacting each other. The tag is responsive to deviations of the actual resistance from the baseline resistance.