Magnetic Element Temperature Sensors for High-Temperature Closed-Loop Control
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Solution Overview
Problem
Current wireless temperature sensing systems are expensive, unable to operate continuously above 125° C, and fail to transmit information in the presence of metal or conducting materials, lacking the ability to carry data related to the object or heating instructions, and are not suitable for closed-loop feedback heating systems.
Innovation Solution
Development of magnetic temperature sensors with magnetically susceptible elements exhibiting a re-magnetization response to alternating magnetic fields, allowing for temperature-sensitive monitoring and control, using microwires with modified chemistries and ferromagnetic sheaths, and a detector system with a decoding algorithm to determine object temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If RFID temperature sensing systems are used, then wireless temperature sensing is achieved, but the system becomes expensive and cannot operate continuously above 125° C
Solution Approach 1:
The patent changes the physical state and magnetic properties of the sensing element by using amorphous or nanocrystalline metal materials with specific Curie temperatures. These materials undergo reversible magnetic transitions at temperatures above 125° C, enabling continuous operation in high-temperature environments where traditional RFID tags fail.
Solution Approach 2:
The patent employs composite structures combining amorphous or nanocrystalline metal cores with insulating coatings. This composite design allows the metal core to sense high temperatures through magnetic property changes while the insulating coating protects the element, enabling reliable continuous operation above 125° C.
2Loss of information
If RFID tags are embedded within conducting materials, then temperature sensing is possible, but the ability to transmit information is lost in the vicinity of metal
Solution Approach 1:
The patent replaces the traditional RFID electromagnetic coupling mechanism with a magnetic field-based detection system. The detector uses magnetic field perturbations caused by the Curie temperature transition of the sensing element, which can penetrate and function effectively near metal objects where traditional electromagnetic RFID communication fails.
3Ease of manufacture
If magnetic element markers are used, then cost is reduced and high temperature operation is enabled, but the ability to carry data related to object or heating instructions is limited
Solution Approach 1:
The patent designs the magnetic sensing element to serve multiple functions: it acts as both the temperature sensing element and the information carrier. The element can encode temperature data through its magnetic state changes and also carry additional object identification or heating instructions data through its magnetic properties, eliminating the need for separate RFID tags.
4Extent of automation
If traditional temperature sensors are used, then temperature sensing is achieved, but integration with closed-loop feedback heating systems is insufficient
Solution Approach 1:
The patent creates a feedback-enabled system where the magnetic sensing element continuously monitors temperature through its Curie temperature transitions, and this information is fed back to a controller that adjusts heating power accordingly. The detector reads the magnetic state changes in real-time, enabling automated closed-loop temperature control without complex additional 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 solution provides a cost-effective, reliable, and efficient wireless temperature sensing system capable of operating above 125° C, transmitting information near metal, and integrating with closed-loop heating systems to control object temperature accurately.
Implementation Method 1
having a re-magnetization response under the influence of an applied alternating magnetic field which is different below and above at least one set point temperature, such as the Curie temperature of the sensor element
Implementation Method 2
an applied alternating magnetic field which is different below and above at least one set point temperature
Data Source
Figure 1~4A
Figure 3A~3C
Figure 5~8
AI summary
Small, low-cost wireless temperature sensors (26, 64, 96) are provided for sensing the temperature of an object (44). The temperature sensors (26, 64, 96) preferably include a plurality of individual, magnetically susceptible temperature sensor elements (28-34, 66, 92), as well as optional magnetic field-responsive data elements (38, 40, 20) adapted for attachment to object (44) or to a substrate (82) in turn attached to object (44). The temperature sensor elements (28-34, 66, 92) preferably have magnetic bodies (22, 70) exhibiting a re-magnetization response under the influence of an applied alternating magnetic field, which is different below and above a set point temperature, normally the Curie temperature of the magnetic body (22) or an adjacent sheath (74, 94). The temperature sensors (26, 64, 96) are used in conjunction with a detector (46) operable to generate a magnetic field of magnitude sufficient to cause re-magnetization responses of the temperature sensor elements (28-34, 66, 92) and optional data elements (38, 40, 20), to detect such responses, and to use the detected responses to determine the temperature of object (44) by means of a decoding algorithm. The temperature sensors (26, 64, 96) can be used in closed-loop heating systems (98) capable of controlling the heating of an object (114).