Tympanic Thermometer Sensor Can Thermal Isolation
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Solution Overview
Problem
Existing tympanic thermometers face inaccuracies due to ambient temperature changes affecting the thermopile sensor, leading to temperature measurement errors, especially when transitioning from room temperature to a human ear environment.
Innovation Solution
A tympanic thermometer design featuring a heat sensing probe with a nozzle and a thermally insulated sensor can, where the sensor can is in thermal contact only with the nozzle, minimizing heat transfer and reducing temperature gradients across the sensor, thus enhancing measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the thermopile sensor is exposed to ambient temperature changes during transition from room temperature to human ear environment, then the sensor responds quickly to temperature changes, but measurement accuracy deteriorates due to temperature gradients across the sensor
Solution Approach 1:
The sensor assembly is segmented into distinct thermal zones: the thermopile sensor element is isolated from the main sensor can body through thermal isolation structures, creating separate thermal pathways. This segmentation allows the sensor element to respond quickly to ear canal temperature while the sensor can body remains thermally stable, resolving the contradiction between fast response and measurement accuracy
Solution Approach 2:
A thermal isolation structure acts as an intermediary between the sensor can body and the thermopile sensor element. This intermediary component selectively blocks heat transfer pathways, allowing the sensor element to be thermally coupled to the ear canal environment for rapid response while preventing unwanted heat transfer from the sensor can body that would create measurement errors
2Stability of the object's composition
If thermal contact between sensor can and surrounding structures is increased, then mechanical stability improves, but temperature measurement accuracy worsens due to additional heat transfer paths
Solution Approach 1:
The thermal and mechanical connections are segmented into separate pathways. Mechanical support structures provide structural stability without creating thermal contact, while thermal isolation structures prevent heat transfer. This segmentation allows independent optimization of mechanical stability and thermal performance
Solution Approach 2:
Different regions of the sensor assembly have different thermal properties: the sensor can body has high thermal mass and is thermally isolated for stability, while the sensor element mounting region has low thermal mass and is thermally coupled to the ear canal for accurate measurement. This local differentiation of thermal quality resolves the contradiction between overall stability and local measurement accuracy
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 design significantly reduces temperature measurement errors, maintaining accuracy over time and across varying ambient temperatures, providing more reliable core body temperature readings.
Implementation Method 1
Tympanic thermometers measure temperature by sensing infrared emissions from the tympanic membrane (eardrum) in the external ear canal
Implementation Method 2
Known tympanic thermometers typically include a probe containing a heat sensor such as a thermopile
Implementation Method 3
a heat sensing probe with a nozzle and a thermally insulated sensor can, where the sensor can is in thermal contact only with the nozzle, minimizing heat transfer
Implementation Method 4
when a tympanic thermometer at room temperature is placed in the human ear, heat transfers to the thermopile sensor and other portions of the tympanic thermometer
Implementation Method 5
The thermopile sensor includes sensor optics and a sensor can. The sensor optics and can temperature are caused to increase very rapidly and thus emit radiation back to the membrane inside the thermopile sensor
Data Source
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AI summary
A tympanic thermometer includes a thermally conductive nozzle (100) extending from a distal end of the thermometer. A base of a sensor can (102) is thermally connected to the nozzle to define a path of conductive heat transfer from the nozzle to the base of the can thereby minimizing a thermal gradient between proximal and distal ends of the sensor can when temperature is measured in the ear.