Concentric Thermopile Layout for Compact Body Temperature Sensing
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Solution Overview
Problem
Existing temperature sensing systems, particularly in compact devices like smartwatches, face integration challenges due to the height difference between thermopiles, which complicates design and affects accuracy in measuring internal body and ambient temperatures.
Innovation Solution
A dual heat flux sensor with concentrically arranged thermopiles of uniform height and processing circuitry that accounts for thermal resistance variations in skin and air to accurately determine internal body and ambient temperatures using temperature gradients and absolute temperature sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermopiles with height difference are used to measure temperature gradients, then temperature measurement capability is improved, but device complexity and integration difficulty increase due to space considerations in compact housing
Solution Approach 1:
The patent transitions from vertical temperature gradient measurement (requiring height difference between thermopiles) to lateral temperature gradient measurement (using side-by-side thermopiles with different heat paths). This dimensional change allows temperature sensing in compact housing without vertical space constraints, resolving the contradiction between measurement capability and integration difficulty.
2Device complexity
If single thermopile is used for temperature measurement, then device complexity is reduced, but measurement precision deteriorates due to inability to account for thermal resistance variances
Solution Approach 1:
The patent divides the temperature measurement function into multiple independent thermopiles, each measuring temperature gradient along different heat paths. This segmentation allows the system to capture thermal resistance variances by comparing measurements from multiple thermopiles, thereby improving measurement precision without requiring a single complex sensor.
Solution Approach 2:
The patent makes the temperature sensing system multi-functional by using multiple thermopiles to simultaneously measure temperature gradients along different heat paths, enabling the system to account for both internal body temperature and ambient temperature variations, as well as thermal resistance characteristics of skin and air.
3Adaptability or versatility
If thermopiles with large height difference are used, then temperature gradient measurement range is improved, but manufacturing precision and integration accuracy deteriorate
Solution Approach 1:
The patent replaces vertical height differential with lateral spatial arrangement of thermopiles. Instead of controlling precise height differences in the vertical dimension, the system uses thermopiles positioned side-by-side with different heat path lengths, achieving temperature measurement range without the manufacturing precision challenges of vertical alignment.
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 measurement of thermal resistance and temperature by compensating for individual variations in skin and air properties, enhancing accuracy and compactness in temperature sensing systems.
Implementation Method 1
a thermopile can include a series-connected thermocouples and output a voltage measurement that is directly proportional to a temperature gradient and/or heat flux
Implementation Method 2
Temperature gradient measurements of the thermopiles can be used for determining heat flux (e.g., through an electronic device)
Implementation Method 3
an absolute temperature sensor configured to measure an absolute temperature at the front crystal
Data Source
AI summary
A temperature sensing system includes absolute temperature sensor(s) and/or thermopiles that form concentric geometries and are uniform in height. In some examples, the temperature sensing system can determine internal body temperature and/or ambient temperature based at least on a thermal gradient associated with the inner thermopile, a thermal gradient associated with the outer thermopile, a lateral temperature difference between the inner and the outer thermopiles, and an absolute temperature. In some examples, the temperature sensing system can determine the internal body temperature and/or ambient temperature using at least four absolute temperature sensors forming a concentric structure.