Semiconductor Junction Orientation in MR Magnetic Fields
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Solution Overview
Problem
Semiconductor components in cryogenic MR systems face challenges such as charge carrier deflection in strong magnetic fields, freezing of charge carriers at low temperatures, dissipation issues, and signal modulation due to cooling mediums, leading to reduced conductivity and increased noise, especially in high-field MRI applications.
Innovation Solution
The semiconductor components are mounted directly on a substrate with good thermal conduction properties, such as ceramic aluminum oxide or sapphire, with their junctions oriented so that the average direction of charge carrier motion is parallel to the magnetic field lines, eliminating the need for magnetizable housings and minimizing thermal and electrical disruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If semiconductor components are cooled to cryogenic temperatures to reduce thermal noise, then noise reduction is achieved, but charge carriers freeze out and conductivity decreases
Solution Approach 1:
The patent applies parameter changes by carefully selecting the operating temperature range (above 77K when using liquid nitrogen cooling) to maintain charge carrier mobility while achieving noise reduction. This temperature parameter optimization prevents complete freezing of charge carriers while still providing significant thermal noise reduction compared to room temperature operation.
Solution Approach 2:
The patent introduces an intermediary cooling system using liquid nitrogen as a cooling medium. The liquid nitrogen provides a controlled thermal environment that mediates between the need for low temperature (noise reduction) and the need to maintain sufficient thermal energy (charge carrier mobility). The cooling system acts as an intermediary that enables operation in the optimal temperature window.
2Adaptability or versatility
If semiconductor components are placed in strong magnetic fields to enable high-field MRI applications, then imaging capability is improved, but charge carriers are deflected and conductivity decreases
Solution Approach 1:
The patent addresses the magnetic field effect by optimizing semiconductor material selection and geometric configuration. By changing parameters such as material type (e.g., using materials with higher mobility) and junction orientation relative to the magnetic field, the system maintains conductivity in high-field environments (1T and above) while enabling high-field MRI applications.
3Strength
If semiconductor components are mounted in magnetizable housings to protect them, then mechanical protection is improved, but magnetic field distortion and noise increase
Solution Approach 1:
The patent extracts the magnetizable housing material from the system by specifying non-magnetizable materials for the housing and mounting structure. This removal of the harmful magnetic material eliminates field distortion and noise while maintaining mechanical protection through alternative non-magnetizable structural designs.
Solution Approach 2:
The patent changes the material parameter of the housing from magnetizable to non-magnetizable materials. This material substitution eliminates the harmful interaction with the magnetic field while preserving the protective function through carefully designed non-magnetizable structural alternatives.
4Temperature
If cooling mediums are used to cool semiconductor components, then temperature control is improved, but signal modulation occurs due to the cooling medium
Solution Approach 1:
The patent uses an intermediary approach by selecting liquid nitrogen as a remote cooling medium rather than placing the semiconductor directly in contact with the cooling agent. The liquid nitrogen cools the housing and mounting structure indirectly, which then conducts heat away from the semiconductor. This intermediary cooling path minimizes direct interaction between the cooling medium and the semiconductor, reducing signal modulation effects.
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 configuration ensures undistorted semiconductor characteristics and effective cooling, reducing noise and increasing the reliability of semiconductor components in strong magnetic fields and low temperatures, enhancing the performance of MR systems.
Implementation Method 1
mounted directly on a substrate with good thermal conduction properties
Implementation Method 2
charge carrier deflection in strong magnetic fields
Data Source
AI summary
An electrical circuit with one or more semiconductor components (10) is characterized in that at least one semiconductor junction of at least one of the semiconductor components of the electrical circuit is disposed such that the average direction of motion of the charge carriers in the semiconductor junction is essentially parallel to the lines of force of the magnetic field B0, wherein the corresponding semiconductor component is disposed directly on a substrate (12), which is made of a material with good thermal conduction properties. In this way, undistorted characteristics of the semiconductor component used can be ensured despite the very strong magnetic field and the low operating temperatures.