Flexible Fabric Temperature Sensor for Zero Heat Flux Body Monitoring
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Solution Overview
Problem
Existing core body temperature sensors lack flexibility and comfort, making them unsuitable for applications where the skin is moving, such as in newborns or general use outside the hospital, and are obtrusive due to their design.
Innovation Solution
A flexible temperature sensor integrated into fabric layers with a central heater and thermistors that follow the skin surface, allowing for continuous monitoring through a garment like a cap or patch, with optional wireless transmission and minimal power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If prior art heat flux temperature sensors are used, then measurement accuracy is achieved, but flexibility is insufficient to follow moving skin surfaces
Solution Approach 1:
The temperature sensor is constructed as a fabric patch with flexible printed circuit boards and thin film components, allowing it to conform to moving skin surfaces while maintaining measurement accuracy. The flexible substrate enables the sensor to adapt to curved and dynamic body surfaces without compromising the thermal contact needed for accurate heat flux measurements.
Solution Approach 2:
The sensor design changes the physical parameters of the sensor structure by using flexible materials with specific thermal conductivity, elasticity, and thickness parameters that enable both skin conformity and accurate temperature measurement. The flexible PCB and fabric layers are engineered with specific mechanical and thermal properties to resolve the contradiction between flexibility and measurement precision.
2Measurement precision
If prior art temperature sensors are used for newborns or general use, then measurement function is provided, but comfort and usability are reduced due to obtrusive design
Solution Approach 1:
The temperature sensor is designed as a disposable fabric patch that can be easily applied and removed without causing discomfort or residue. This disposable nature eliminates the need for repeated cleaning and reduces skin irritation, significantly improving comfort and ease of operation for newborns and general use while maintaining continuous temperature monitoring capability.
Solution Approach 2:
The thin fabric construction and flexible components make the sensor nearly invisible and comfortable to wear, eliminating the obtrusive appearance and discomfort associated with prior art sensors. The flexible design allows natural skin movement and breathing without restriction, greatly enhancing usability for newborns and general population.
3Adaptability or versatility
If flexible fabric layers are used, then comfort and skin conformity are improved, but device complexity increases
Solution Approach 1:
The fabric layers serve multiple functions simultaneously: they provide mechanical flexibility for skin conformity, thermal insulation, structural support for embedded components, and even contribute to the thermal management of the sensor. This multi-functionality reduces the need for separate dedicated components, thereby managing device complexity while maintaining high flexibility.
Solution Approach 2:
Multiple functional layers (flexible substrate, insulation layer, circuit board, thermistor mounting) are merged into a single integrated fabric patch structure. The flexible printed circuit board technology allows integration of electrical pathways, component mounting, and mechanical flexibility in a single layer, significantly reducing overall device complexity compared to assembling separate components.
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 flexible sensor provides accurate and unobtrusive body temperature monitoring, enhancing comfort and usability in low acuity settings and outside the hospital, while maintaining accuracy by minimizing air gaps and heat loss.
Implementation Method 1
The at least one third layer is adapted to be in contact to the skin of the surface of the body for conducting the heat escaping from the body through the layers
Implementation Method 2
a second thermistor embedded therein separated from the first thermistor for measuring at least one second temperature value
Implementation Method 3
the heat emitted from central heater is tuned oppositely to the vertical heat flux until a zero heat flux is reached, where the temperature at the at least one second thermistor at zero heat flux indicates the body temperature
Data Source
AI summary
This invention relates to a temperature sensor for body temperature measurements. The temperature sensor is made of several layers, where a first layer has a central heater embedded therein, a second layer which is attached to the first layer has at least one first thermistor embedded therein for measuring a first temperature value, a third layer has at one ore second thermistor embedded therein separated from the first thermistor for measuring at least one second temperature value, but this third layer is adapted to be in contact to the skin of the surface of the body for conducting the heat escaping from the body through the layers. The difference between the first and the second temperature values indicates the heat flux from the body. The heat emitted from central heater is tuned oppositely to the heat flux until a zero heat flux is reached, where the temperature at the at least one second thermistor at zero heat flux indicates the body temperature. These layers are fabric layers.