Diaper Loading Detection Through Color Sensing and Activity State

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Solution Overview

Problem

Existing methods for determining the level of bodily exudate in absorbent articles, such as diapers, are inaccurate due to reliance on temperature or humidity sensors that may not be representative of the article's overall condition and are prone to errors from wearer movement.

Innovation Solution

A system using a color detection method with a pulsed light source and photodetector to measure the color change of a color-changing indicator in a diaper, combined with an activity classification system via inertial sensors to determine the activity state of the wearer, improving accuracy by filtering out ambient light and correcting for movement-related errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If temperature or humidity sensors are used to detect bodily exudate level, then the detection can be implemented with simple sensors, but the measurement accuracy deteriorates due to sensor location not being representative and errors from wearer movement

Engineering Contradiction:

Improvesensor implementation simplicityVSAvoidbodily exudate level detection accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent replaces mechanical/physical sensors (temperature and humidity sensors) with an optical detection system using a light source and photodetector. This optical system measures light absorption or reflection properties of the absorbent article, which directly correlate to the amount of bodily exudate absorbed, thereby improving measurement accuracy while maintaining ease of implementation

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes color-changing indicators within the absorbent article that change color based on the level of bodily exudate absorption. The optical detection system detects these color changes by measuring light absorption or reflection at different wavelengths, providing accurate real-time monitoring of exudate levels without being affected by wearer movement or sensor positioning issues

Inventive Principle:

Principle #32Color changes

2Productivity

If ambient light is not filtered out, then the photodetector can continuously measure light reflected from the absorbent article, but the measurement accuracy deteriorates due to ambient light interference

Engineering Contradiction:

Improvecontinuous measurement capabilityVSAvoidlight reflection measurement accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent employs periodic pulsing of the light source rather than continuous illumination. The light source is pulsed at specific intervals, and the photodetector synchronously measures light reflection during these pulses. This periodic action allows the system to distinguish between light from the source and ambient light, enabling accurate measurements while maintaining continuous monitoring capability

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system incorporates ambient light sensing capability that provides feedback to the control mechanism. By measuring ambient light levels and using this information to adjust or compensate for ambient light interference in the main measurements, the system maintains high measurement accuracy while operating continuously in varying ambient light conditions

Inventive Principle:

Principle #23Feedback

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

Accurately determines the volume of bodily exudate in diapers by accounting for ambient light and wearer activity, enhancing the reliability and precision of diaper change timing.

Implementation Method 1

obtains a second measurement from the photodetector while the light source is transmitting light on the absorbent article. The second measurement includes a measurement of the ambient light and the transmitted light reflected from an absorbent article

Methodology Applied

Scientific EffectLight reflection: Reflection

Implementation Method 2

determining a volume of bodily exudate present in an absorbent article and more specifically relates to determining a volume of urine in a diaper based on a changing color of a color changing indicator the diaper

Methodology Applied

Scientific EffectColor change indication: Photochromism

Data Source

PatentUS12458543B2Determining diaper loading using color detection or activity state

Publication Date: 2025.11.04 VERILY LIFE SCIENCES LLC

AI summary

Systems and methods for detecting determining a volume of urine in an absorbent article such as a diaper. A diaper loading application obtains a first measurement of ambient light received from a photodetector while a light source is off and a second measurement from the photodetector while the light source is transmitting light on an absorbent article. The application determines a normalized measurement of light reflected from an absorbent article by removing an ambient light signal from the second measurement based on the first measurement. The application determines, from the normalized measurement, a presence of urine in the absorbent article. The application further determines an estimated volume of urine in the absorbent article, wherein the determining is based on an elapsed time since the presence of urine and an activity state of an infant wearing the absorbent article.