NMR Temperature Sensor Tube with Gas Flow for Thermal Conduction
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Solution Overview
Problem
Existing NMR measuring configurations face challenges in minimizing the temperature penetration factor, leading to significant differences between sensor and sample temperatures, which affects the accuracy of temperature control and the quality of NMR measurements, especially due to external temperature influences and the need for local calibration across a wide temperature range.
Innovation Solution
The temperature sensor and its supply wires are surrounded by a sensor tube with a temperature-control gas flow that counteracts longitudinal thermal conduction, allowing the temperature sensor to be positioned close to the sample vial, reducing the temperature penetration factor and eliminating the need for local calibration by maintaining a consistent temperature measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the temperature sensor is positioned close to the sample vial to minimize temperature difference, then measurement precision improves, but the temperature penetration factor increases making the sensor sensitive to external temperature influences
Solution Approach 1:
A non-magnetic, thermally conductive intermediary material (such as ceramic or plastic) is introduced between the temperature sensor and the external environment. This intermediary allows thermal equilibrium with the sample while blocking the direct path for external temperature influences and RF interference, thus maintaining measurement precision without increasing temperature penetration factor
Solution Approach 2:
The sensor housing is designed with differentiated thermal properties: the inner portion in contact with the sample has high thermal conductivity to ensure temperature equilibrium, while the outer portion has low thermal conductivity to isolate external temperature influences. This local quality differentiation resolves the contradiction between needing close thermal contact and avoiding external thermal interference
2Object-affected harmful factors
If the temperature sensor is positioned far from the sample vial to reduce temperature penetration factor, then external temperature influence decreases, but the difference between sensor temperature and sample temperature increases
Solution Approach 1:
The temperature sensor is nested within a multi-layered housing structure that provides both thermal isolation from external influences and thermal coupling to the sample. The sensor is positioned within an inner chamber that is thermally coupled to the sample vial, while outer layers provide insulation, effectively nesting the sensing function within a protective thermal environment
3Measurement precision
If calibration is performed across the entire temperature range, then measurement precision improves, but the complexity of calibration procedures increases
Solution Approach 1:
The system performs preliminary automatic calibration actions at predetermined temperature points before actual measurements. The microcontroller pre-loads calibration data for multiple temperature points into memory, and during operation automatically interpolates between these pre-calibrated points, eliminating the need for manual calibration across the entire temperature range while maintaining high measurement precision
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 significantly reduces the temperature penetration factor, allowing for precise temperature control and stable NMR measurements across a wide temperature range without the need for local calibration, ensuring accurate sample temperature setting and minimizing external temperature influences.
Implementation Method 1
The temperature-control gas flow (Vout2) counteracts the longitudinal thermal conduction in the supply wire
Implementation Method 2
a partial flow of the temperature-control fluid flows as the temperature-control flow out of the measurement space into the free space between the temperature sensor and the inner wall of the sensor tube
Implementation Method 3
which is temperature controlled in the supply flow to the measurement space by a closed-loop-controlled heater
Data Source
AI summary
An NMR measuring configuration has a temperature control device for a sample vial (1). The temperature control device has a temperature sensor with supply wires which are both surrounded by a sensor tube (15). The sensor tube (15) is connected to a measurement space via a sensor flow inlet (26) in such a way that a partial flow of a temperature-control fluid flows as a temperature-control flow (16) into a free space (17) between the temperature sensor and the inner wall of the sensor tube along the supply wires and flows out of the sensor tube via a sensor flow outlet (18) at the opposite end of the sensor tube. This minimizes both the temperature penetration factor and the difference between the sensor and sample temperatures (ΔTp).