Wearable Core Temperature Estimation Using Heat Flux and Perfusion
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Solution Overview
Problem
Compact wearable devices face challenges in measuring core body temperature due to limited space, making it difficult to incorporate multiple sensors needed for accurate estimation.
Innovation Solution
An electronic device with a first temperature sensor for skin surface measurement, a second temperature sensor inside the device, and heating elements to estimate heat flux and blood perfusion rate, using a processor to calculate core body temperature based on these measurements and a human heat model.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensors are used to collect various data points for core body temperature measurement, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple measurement functions (skin temperature, internal device temperature, heat flux, and blood perfusion rate) into a single integrated sensor system. The first temperature sensor measures skin surface temperature, the second temperature sensor measures internal device temperature, and heating elements work together with these sensors to derive multiple physiological parameters, reducing the need for separate specialized sensors for each measurement type.
Solution Approach 2:
The temperature sensors and heating elements serve multiple functions: the first temperature sensor measures skin temperature for both direct temperature monitoring and heat flux calculation; the second temperature sensor measures internal temperature for thermal contact resistance assessment; the heating elements generate controlled heat for blood perfusion rate estimation while also serving as temperature sources for the sensors.
2Measurement precision
If multiple sensors are used to collect various data points for core body temperature measurement, then measurement precision is improved, but ease of manufacture worsens
Solution Approach 1:
The patent integrates multiple sensing and heating functions into a compact arrangement where the first temperature sensor, second temperature sensor, and heating elements are positioned in close proximity on the contact surface. This merged design reduces the number of separate components that need to be manufactured and assembled, simplifying the manufacturing process while maintaining the capability to collect multiple data points for accurate core body temperature estimation.
3Measurement precision
If heating elements are added to estimate blood perfusion rate and heat flux, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The heating elements operate in periodic cycles rather than continuously, applying controlled heating pulses to estimate blood perfusion rate and heat flux. This periodic operation reduces overall energy consumption compared to continuous heating, while still gathering sufficient data points for accurate core body temperature estimation through the thermal response measurements during and after heating phases.
Solution Approach 2:
The heating elements apply controlled, localized heating to specific regions rather than heating the entire device or body surface. This partial action approach uses minimal energy to generate the necessary thermal signals for blood perfusion rate and heat flux estimation, achieving the measurement precision goal with reduced energy expenditure compared to comprehensive heating approaches.
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
Accurately estimates core body temperature in a compact form factor by reducing the number of sensors required, enhancing estimation accuracy through heat flux and blood perfusion rate calculations.
Implementation Method 1
a first temperature sensor configured to measure a first temperature of a skin surface of a user when the user comes into contact with a main body of the electronic device
Implementation Method 2
a second temperature sensor spaced apart from the first heating element by a second predetermined distance and configured to measure a second temperature inside the main body
Implementation Method 3
a first heating element spaced apart from the first temperature sensor by a first predetermined distance
Implementation Method 4
estimate heat flux based on the first temperature and the second temperature
Data Source
AI summary
An electronic device may include: a first temperature sensor configured to measure a first temperature of a skin surface when a user comes into contact with a main body of the electronic device; a first heating element spaced apart from the first temperature sensor by a first predetermined distance; a second temperature sensor spaced apart from the first heating element by a second predetermined distance and configured to measure a second temperature inside the main body; and a processor configured to: estimate heat flux based on the first temperature and the second temperature; estimate a blood perfusion rate of the user based on a temperature of the first heating element and the first temperature, and estimate a core body temperature of a user based on the first temperature, the estimated heat flux, and the estimated blood perfusion rate.