In-Ear Dual Temperature Sensing for Accurate Core Body Readings
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Solution Overview
Problem
Existing technologies face challenges in obtaining accurate and direct temperature measurements from the tympanic membrane due to the narrow and angular ear canal, limiting the field of view for infrared sensors, and require a means to compensate for environmental temperature changes while ensuring low power consumption and small device sizes.
Innovation Solution
Positioning temperature sensors at specific locations within the ear canal, such as Location 2, and using a heat balance equation to calculate absolute core body temperature, incorporating thermistors for low power consumption and accuracy, and designing thermistor-to-ear interfaces to minimize temperature variability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a handheld IR sensor is used to measure tympanic membrane temperature, then temperature measurement capability is achieved, but measurement accuracy deteriorates due to limited field of view through the narrow and angular ear canal
Solution Approach 1:
The device divides the temperature sensing function into two separate sensors: a distal temperature sensor positioned near the tympanic membrane to capture radiant heat, and a proximal temperature sensor positioned in the outer ear to measure ambient temperature. This segmentation allows each sensor to operate in its optimal measurement zone, resolving the field of view limitation while maintaining measurement accuracy.
Solution Approach 2:
The patent introduces an intermediary computational approach using a heat balance equation that processes readings from both distal and proximal sensors. This intermediary calculation compensates for the limited direct field of view by mathematically deriving accurate tympanic membrane temperature from the combined sensor data and known thermal properties of ear canal tissues.
2Measurement precision
If multiple temperature sensors are positioned at different locations in the ear canal, then measurement accuracy improves through heat balance calculation, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-establishing the heat balance equation with known thermal properties of ear canal tissues before actual measurement. This pre-computed model allows the device to directly apply the formula using real-time sensor readings, rather than requiring complex real-time simulations, thereby reducing computational complexity while maintaining high measurement accuracy.
3Use of energy by moving object
If thermistors are used for temperature sensing, then power consumption is reduced and accuracy is improved, but device design complexity increases due to interface requirements
Solution Approach 1:
The patent applies local quality by designing the thermistor-to-ear interface with specific thermal coupling characteristics at the measurement location. The interface is engineered to optimize thermal contact between the thermistor and ear canal tissues at the proximal sensor position, ensuring accurate ambient temperature measurement while keeping the overall device design manageable through localized interface optimization rather than system-wide complexity.
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
Achieves accurate core body temperature measurements with an error of +/−0.5°C and rapid response to temperature changes, addressing the limitations of existing ear-based temperature sensing systems.
Implementation Method 1
The distal temperature sensor is configured to sense one or both of conductive heat and convective heat and to produce a first temperature signal
Implementation Method 2
The distal temperature sensor is configured to sense one or both of conductive heat and convective heat and to produce a first temperature signal
Implementation Method 3
The proximal temperature sensor is configured to sense one or both of conductive heat and convective heat and to produce a second temperature signal
Implementation Method 4
The proximal temperature sensor is configured to sense one or both of conductive heat and convective heat and to produce a second temperature signal
Data Source
AI summary
An electronic device comprises an enclosure configured for insertion into the ear canal and comprising a distal end configured to extend at least beyond a first bend of the ear canal. A distal temperature sensor is situated at a location of the enclosure that faces a tragus-side of the ear canal between the first and second bends when the enclosure is fully inserted into the ear canal. A proximal temperature sensor is situated on the enclosure at a location spaced apart from a surface of the ear canal and proximal of the distal temperature sensor in an outer ear direction when the enclosure is fully inserted into the ear canal. A processor, coupled to the distal and proximal temperature sensors and to memory, is configured to calculate an absolute core body temperature using a heat balance equation stored in the memory and the first and second temperature signals.