Light Guide for Tympanic Temperature Measurement
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Solution Overview
Problem
Existing body core temperature measurement methods through the tympanic membrane face challenges when the ear canal is obstructed, requiring an optical design that allows the sensor to be located less deeply or outside the ear canal while maintaining a clear field of view for accurate readings.
Innovation Solution
A device using a light guide with a reflective interior and optional lens, positioned parallel to the earpiece's sound tube, limits the acceptance angle and minimizes debris entry, allowing for accurate infrared radiation measurement from the eardrum by restricting the field of view and using a hollow reflective tube or optic fiber to direct LWIR radiation to a thermopile sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor is positioned deeper in the ear canal to fill the field of view with the tympanic membrane, then measurement precision is improved, but device complexity and ease of operation worsen due to obstruction by other components and physiological variations
Solution Approach 1:
A light guide is introduced as an intermediary component between the sensor and the tympanic membrane. The light guide transmits infrared radiation from the tympanic membrane to the sensor, allowing the sensor to be positioned outside or at the entrance of the ear canal rather than deep inside, thus resolving the contradiction between measurement precision and ease of operation
Solution Approach 2:
The solution moves the sensor positioning problem from the longitudinal dimension (depth in ear canal) to the transverse dimension (positioning at ear canal entrance with light guide extending in). This dimensional shift allows the sensor to maintain field of view coverage without requiring deep insertion
2Ease of operation
If the sensor is positioned outside the ear canal to improve ease of operation, then ease of operation is improved, but measurement precision deteriorates due to increased standoff distance reducing field of view coverage
Solution Approach 1:
The light guide serves as a mediator that extends the optical path from the tympanic membrane to the externally positioned sensor, maintaining field of view coverage despite the increased physical distance and allowing the sensor to remain accessible outside the ear canal
3Measurement precision
If a light guide with reflective interior is used to direct infrared radiation to the sensor, then measurement precision is improved, but device complexity increases due to additional optical components
Solution Approach 1:
The light guide with reflective interior acts as an intermediary optical component that collects and directs infrared radiation from the tympanic membrane to the sensor, improving measurement precision while adding only a single integrated component rather than multiple complex optical elements
Solution Approach 2:
The light guide performs multiple functions: it serves as the optical path for infrared radiation transmission, provides structural support for sensor positioning, and defines the field of view through its geometry, thereby reducing overall device complexity through functional integration
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
This solution enables accurate and reliable body core temperature monitoring by reducing the impact of debris and ambient thermal gradients, maintaining measurement accuracy even with varying ambient temperatures, and allowing for flexible fiber optic bundles for user comfort.
Implementation Method 1
a light guide with a reflective interior and optional lens, positioned parallel to the earpiece's sound tube
Implementation Method 2
allowing for accurate infrared radiation measurement from the eardrum by restricting the field of view and using a hollow reflective tube or optic fiber to direct LWIR radiation to a thermopile sensor
Implementation Method 3
using a hollow reflective tube or optic fiber to direct LWIR radiation to a thermopile sensor
Data Source
AI summary
An apparatus for measuring body core temperature includes a light guide with an internally reflective tube. The light guide is coupled to an earpiece, and has a lens or an aperture positioned at one of its ends. A sensor is positioned at the other end of the light guide, and a processor is coupled to the sensor. The sensor senses infrared radiation from an infrared source at the end of the light guide, and the processor determines a temperature of the infrared source at the end of the light guide via a transfer function that correlates a measure of the infrared radiation observed by the sensor and an effect of radiation of the light guide.