Cryocooled SQUID measurement apparatus
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Solution Overview
Problem
Current cryocooler SQUID systems face challenges with cyclic magnetic noise and thermal noise, which distort biomagnetic signals and limit the sensitivity and stability of SQUID apparatus, particularly due to the integration of the cold head and sensor chamber, and the need for high-priced liquid helium and specialized magnetic shielding.
Innovation Solution
A cryocooler SQUID system design where the cold head chamber is separated from the sensor chamber, using a superconductive shield to remove cyclic magnetic noise and thermal noise, and a ferromagnetic cold head shield to reduce external noise, allowing for improved thermal transfer and magnetic isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cryocooler is used to cool the SQUID sensor instead of liquid helium, then the operational cost and safety risks are reduced, but cyclic magnetic noise is generated by the regenerator materials that distorts the biomagnetic signal
Solution Approach 1:
The patent extracts and removes the regenerator component that generates cyclic magnetic noise from the cryocooler system. By eliminating the regenerator, the system avoids the magnetic noise problem while maintaining the benefits of cryocooler operation, thus resolving the contradiction between operational safety and magnetic noise generation.
Solution Approach 2:
The patent converts the harmful cyclic magnetic noise generated by regenerator materials into a benefit by using the cryocooler's cold head to directly cool the SQUID sensor without a regenerator, thereby eliminating the noise source while maintaining efficient cooling. This transforms the potential harm into a clean cooling solution.
2Use of energy by moving object
If indirect cooling technique is used with high thermal conductivity metal, then heat transfer from cryocooler to SQUID sensor is improved, but thermal noise from the metal reduces operation stability and sensitivity
Solution Approach 1:
The patent applies local quality by using different materials in different regions: high thermal conductivity metal is used only where needed for heat transfer (in the thermal connection path), while the SQUID sensor and its immediate environment use low-noise materials and magnetic shielding. This localized approach maintains heat transfer efficiency while minimizing thermal noise impact on sensor performance.
Solution Approach 2:
The patent introduces an intermediary thermal anchor that acts as a buffer between the cryocooler and the SQUID sensor. This thermal anchor provides a stable thermal interface that reduces direct thermal noise coupling while maintaining efficient heat transfer, thus resolving the contradiction between heat transfer efficiency and operational stability.
3Device complexity
If cold head and sensor chamber are integrated into one body, then structural simplicity is achieved, but magnetic noise from cold head distorts the signal and requires complex digital filtering that causes information loss
Solution Approach 1:
The patent segments the system into separate functional modules: the cryocooler cold head is separated from the sensor chamber, with only necessary thermal and structural connections maintained. This segmentation allows the cold head to be positioned away from sensitive measurement areas, reducing magnetic noise interference while maintaining cooling efficiency, thus avoiding the need for complex digital filtering.
Solution Approach 2:
The patent extracts the magnetic noise source (cold head) from the immediate sensor environment by separating the cold head chamber from the sensor chamber. This extraction eliminates the need for complex digital filtering to remove magnetic noise, thereby preventing signal distortion and information loss while maintaining structural simplicity through optimized integration.
4Temperature
If typical SQUID apparatus using liquid helium is used, then cooling performance is achieved, but the apparatus cannot be easily repositioned or reconfigured for different measurement scenarios
Solution Approach 1:
The patent introduces dynamic positioning capability by making the sensor chamber and cold head chamber independently movable relative to each other. The decoupled chamber design allows each module to be repositioned flexibly to accommodate different measurement scenarios (e.g., MEG, MCG, brain function mapping), while maintaining optimal thermal connection for cooling performance.
Solution Approach 2:
By segmenting the apparatus into separable chambers (cold head chamber and sensor chamber), the patent enables independent positioning and reconfiguration of each module. This segmentation provides the adaptability needed for different measurement scenarios while preserving the thermal connection required for effective cooling performance.
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
This design enhances the sensitivity and stability of the SQUID system by reducing noise interference, enabling position changes of the sensor and reducing the reliance on liquid helium, while maintaining effective cooling and signal integrity.
Implementation Method 1
a SQUID sensor removes cyclic magnetic noise and thermal noise by using a superconductive shield
Implementation Method 2
a connection block connecting the cold head and a thermal anchor disposed in the sensor chamber to each other to cool the SQUID sensor in the sensor chamber
Implementation Method 3
a ferromagnetic cold head shield to reduce external noise
Implementation Method 4
A superconducting quantum interference device (SQUID) is used to measure very fine magnetic signals of several tens to several hundreds of femtotesla (fT) which are generated by human activities of brain, heart, muscles
Data Source
AI summary
A cryocooler superconducting quantum interference (SQUID) system includes a cryocooler including a cold head, a cold head chamber in which the cold head is disposed, a sensor chamber including a SQUID sensor cooled to a low temperature by the cryocooler; and a connection block connecting the cold head and a thermal anchor disposed in the sensor chamber to each other to cool the SQUID sensor in the sensor chamber.