Ear-Wearable In-Canal Sensor Layout for Core Temperature Accuracy
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Solution Overview
Problem
Existing technologies face challenges in obtaining accurate and continuous core body temperature measurements from within the ear canal due to the narrow and angular geometry of the ear canal, which obstructs a direct field of view for temperature sensors.
Innovation Solution
An ear-wearable electronic device with a flexible circuit board housing two thermistors in a trough configuration, positioned between the first and second bends of the ear canal, measures conductive and convective heat to calculate core body temperature using a heat balance equation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a handheld IR sensor is used to measure ear canal temperature, then non-contact temperature measurement is achieved, but accurate measurement is hindered by the narrow and angular ear canal geometry obstructing the field of view
Solution Approach 1:
The invention extracts the temperature measurement function from a handheld external device and integrates it into an in-canal wearable device, allowing the sensor to be positioned directly within the ear canal where temperature measurements are taken via conduction from the ear canal walls rather than through line-of-sight infrared measurement
Solution Approach 2:
The invention replaces the infrared optical measurement system with a thermal conduction-based measurement system, where thermistors measure temperature through direct thermal contact with the ear canal tissue, eliminating the need for line-of-sight access through the angular ear canal
2Measurement precision
If temperature sensors are positioned deep in the ear canal for accurate core body temperature measurement, then measurement accuracy improves, but thermal resistance increases and consistent sensor spacing becomes difficult to maintain
Solution Approach 1:
The invention transitions from a single-point temperature measurement approach to a distributed multi-sensor array approach, using multiple thermistors positioned at different locations within the ear canal to capture temperature gradients and enable more accurate core body temperature calculation through heat balance equations
Solution Approach 2:
The invention employs a flexible circuit board to mount the temperature sensors, allowing the sensor array to conform to the curved and angular geometry of the ear canal while maintaining consistent relative spacing between sensors, thereby ensuring reliable thermal contact across varying anatomical configurations
3Measurement precision
If multiple temperature sensors are used to calculate core body temperature through heat balance equations, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The invention integrates multiple temperature sensing functions into a single flexible circuit board module, where the same physical structure supports multiple thermistors and the associated signal processing circuitry, thereby reducing overall device complexity while maintaining the capability for accurate multi-point temperature measurement and core body temperature calculation
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
Enables accurate and continuous core body temperature monitoring by reducing thermal resistance and maintaining consistent sensor spacing, facilitating precise temperature calculations and alerts based on thermal gradients.
Implementation Method 1
measuring, using a distal temperature sensor disposed in a trough of an enclosure of the device, a first temperature indicative of one or both of conductive heat and convective heat
Implementation Method 2
measuring, using a distal temperature sensor disposed in a trough of an enclosure of the device, a first temperature indicative of one or both of conductive heat and convective heat
Data Source
Figure 1
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Figure 2B
AI summary
Embodiments are directed to an electronic device configured to measure temperature from within an ear canal having a first bend, a second bend, and a tympanic membrane. The device comprises an enclosure comprising an in-canal section dimensioned for deployment in the ear canal. The in-canal section comprises a trough extending axially along at least a portion of the in-canal section and arranged to be positioned between the first bend and the tympanic membrane when the in-canal section is fully deployed in the ear canal. A temperature sensor is disposed in the trough. The temperature sensor comprises a flexible circuit board, a distal temperature sensor disposed on the flexible circuit board, and a proximal temperature sensor disposed on the flexible circuit board and situated proximal of, and spaced apart from, the distal temperature sensor in an outer ear direction.