Sample holder for electron microscopy
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Solution Overview
Problem
Current electron microscopy cooling methods using liquid nitrogen suffer from temperature drift, vibration due to nitrogen bubbles, and limitations in sample rotation/angle, with slow cool-down and warm-up times, and high operational costs.
Innovation Solution
A Joule-Thomson refrigerator is thermally coupled to a sample holder via a flexible conductor, integrated with a vacuum pump system and high-pressure gas source, allowing for precise temperature control and minimizing vibrations, using a thermally insulating holder and body parts for efficient cooling within an electron microscope.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If liquid nitrogen is used for cooling, then cooling effect is achieved, but temperature drift and vibration occur
Solution Approach 1:
The patent changes the cooling mechanism from liquid nitrogen phase change to Joule-Thomson effect in a controlled gas expansion system, enabling precise temperature regulation without the temperature drift inherent in liquid nitrogen cooling
Solution Approach 2:
The patent replaces the mechanical liquid nitrogen cooling system with a gas-based Joule-Thomson refrigerator system that uses controlled gas expansion through a throttle valve, eliminating the vibration and instability associated with liquid nitrogen
2Temperature
If liquid nitrogen is used for cooling, then cooling is provided, but vibration due to nitrogen bubbles occurs
Solution Approach 1:
The patent replaces the liquid nitrogen cooling system with a gas-based Joule-Thomson refrigerator that uses controlled expansion of high-pressure gas through a throttle valve, eliminating the bubble formation and associated vibration
Solution Approach 2:
The patent changes from liquid phase cooling to gas phase cooling with controlled expansion, transforming the cooling mechanism to eliminate harmful vibrations while maintaining effective temperature reduction
3Temperature
If liquid nitrogen cooling system is used, then cooling is achieved, but sample rotation and angle adjustment are limited
Solution Approach 1:
The patent divides the cooling system into a separate Joule-Thomson refrigerator unit that can be independently positioned and adjusted, allowing the sample holder to be rotated and angled without being constrained by a fixed liquid nitrogen cooling apparatus
Solution Approach 2:
The patent introduces dynamic adjustment capabilities to the sample holder and cooling system, enabling rotation and angle changes while maintaining thermal coupling through the flexible conductor design
4Temperature
If liquid nitrogen cooling system is used, then cooling is provided, but cool-down and warm-up times are slow
Solution Approach 1:
The patent changes the cooling medium from liquid nitrogen to high-pressure gas with controlled Joule-Thomson expansion, enabling faster heat transfer and quicker response times for both cooling and warming cycles
Solution Approach 2:
The patent enables rapid periodic adjustment of the cooling gas flow and pressure to quickly respond to temperature changes, achieving fast cool-down and warm-up cycles
5Temperature
If liquid nitrogen cooling system is used, then cooling is achieved, but operational costs are high
Solution Approach 1:
The patent changes from expensive liquid nitrogen consumption to a reusable high-pressure gas system with Joule-Thomson cooling, eliminating the need for continuous purchase and replacement of cryogenic liquid
Solution Approach 2:
The patent creates a self-sustaining cooling system where the Joule-Thomson refrigerator uses the expansion of stored high-pressure gas to generate cooling, reducing external resource requirements and operational costs
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 solution provides stable cryogenic conditions with minimal temperature drift and vibration, fast cooling/warming times, and low operational costs, enabling high-resolution imaging without the limitations of liquid nitrogen-based systems.
Implementation Method 1
a Joule-Thomson refrigerator disposed within the cavity and thermally-coupled to the holder part, the refrigerator being coupled in use to the source of high pressure gas to maintain the sample at about a predetermined temperature
Implementation Method 2
a body part defining a cavity, the cavity being evacuated by the vacuum pump system for use
Implementation Method 3
using a thermally insulating holder and body parts for efficient cooling
Data Source
AI summary
The apparatus is for use with an electron microscope, a sample, a source of high pressure gas and a vacuum pump system. The apparatus includes a holder part a body part and a Joule-Thomson refrigerator. The holder part is adapted to receive the sample and adapted to present the sample to the microscope for inspection in use. The body part defines a cavity, the cavity being evacuated by the vacuum pump system for use. The refrigerator is disposed within the cavity and thermally-coupled to the holder part, the refrigerator being coupled in use to the source of high pressure gas to maintain the sample at about a predetermined temperature.