Optical Sensing System for Body Water Content
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Solution Overview
Problem
Accurately determining body water content outside of clinical settings is challenging due to variations among individuals based on factors like age, weight, and height, and existing technologies struggle to provide reliable measurements in real-world scenarios.
Innovation Solution
An electronic device with light emitters and detectors configured to emit light at different wavelengths, measuring the decay constant of light as it interacts with the user's tissue to calculate a water content metric, which can be correlated to body water content, using multiple light paths to increase accuracy and reduce measurement sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple light detectors at different separation distances are used to measure light return, then measurement precision of body water content is improved, but device complexity increases
Solution Approach 1:
The system divides the measurement function into multiple independent light detector channels, each operating at a different separation distance from the light emitter. Each detector measures light return independently, and the processor combines these segmented measurements to calculate the decay constant and determine body water content, thereby improving measurement precision while maintaining manageable device complexity through modular architecture
Solution Approach 2:
The system transitions from single-point measurement to multi-dimensional measurement by positioning light detectors at different separation distances (spatial dimension) from the light emitter. This creates a spatial gradient of light return measurements that provides additional information about tissue optical properties, enabling more accurate determination of body water content through decay constant calculation
2Reliability
If light interaction measurements are taken at multiple separation distances, then reliability of body water content determination is improved, but manufacturing precision requirements increase
Solution Approach 1:
The system incorporates feedback by having the processor calculate the decay constant from the measured light return values at different separation distances. This decay constant serves as a feedback parameter that characterizes the tissue's optical absorption properties, which is then used to determine body water content. The feedback mechanism compensates for variations in absolute separation distances, reducing the impact of manufacturing tolerances on measurement reliability
Solution Approach 2:
The system changes the measurement parameter from absolute light intensity to decay constant, which is derived from the rate of change of light return with respect to separation distance. This parameter transformation makes the measurement less sensitive to absolute positioning accuracy, as the decay constant reflects the relative change in light attenuation across different distances, thereby improving reliability while tolerating broader manufacturing variations
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 enables precise and repeatable determination of body water content, accounting for individual variations and skin pigmentation, allowing for effective hydration monitoring in wearable devices.
Implementation Method 1
measuring a first return of the emitted light that has interacted with the tissue of the user
Implementation Method 2
measuring a second return of the emitted light that has interacted with the tissue of the user
Data Source
AI summary
Embodiments are directed to an electronic device that includes a housing, a light emitter, a first detector positioned at a first separation distance from the light emitter, and a second detector positioned at a second separation distance from the light emitter. The electronic device can include a processor that is configured to cause the light emitter to emit light toward a user, receive a first measurement from the first detector based on a return of the emitted light from tissue of the user and receive a second measurement from the second detector based on a return of the emitted light from the tissue of the user. The processor can determine a decay constant of the emitted light using the first measurements and the second measurements, and determine a water content metric of the user using the determined decay constant.