Cryogenic Sample Cooling with a Rectangular Nozzle for Uniform Vitrification
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Solution Overview
Problem
Existing methods for preparing cryogenic samples using circular nozzles fail to achieve consistent cooling rates across the entire sample, leading to inadequate vitrification and potential damage from ice crystallization, especially at the edges and centers.
Innovation Solution
A method utilizing a flow device with a first nozzle having a non-circular nozzle opening, where the width is larger than the height, creating a 2D flow profile that bifurcates into two sheets of liquid flow, ensuring consistent cooling rates across the sample without causing foil breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If circular nozzles are used for cryogenic cooling, then the cooling process is simple to implement, but the cooling rate is inconsistent across the sample surface
Solution Approach 1:
The patent applies asymmetry by changing the nozzle opening from a circular (symmetric) shape to a rectangular (asymmetric) shape with width larger than height. This asymmetric geometry creates a 2D flow profile that bifurcates into two sheets of liquid flow, which significantly improves cooling rate uniformity across the sample surface compared to traditional circular nozzles.
Solution Approach 2:
The patent transitions from a point-like circular nozzle opening to a rectangular opening that introduces a dimensional aspect (width larger than height), creating a 2D flow profile. This dimensional change allows the cryogenic fluid to spread more effectively across the sample surface, achieving consistent cooling rates without increasing device complexity.
2Reliability
If high cooling rates are applied to achieve rapid vitrification, then ice crystallization is prevented, but the sample may suffer from thermal stress damage
Solution Approach 1:
The rectangular nozzle opening creates a 2D flow profile that delivers consistent cooling rates across different regions (center and edges) of the sample surface. This local quality improvement ensures that the entire sample undergoes uniform rapid cooling, achieving reliable vitrification while distributing thermal stress evenly to prevent localized damage.
3Manufacturing precision
If multiple nozzles are used to improve cooling uniformity, then cooling rate consistency improves, but device complexity and operational difficulty increase
Solution Approach 1:
The patent merges the cooling function into a single rectangular nozzle opening that produces a 2D flow profile. This single nozzle replaces what would traditionally require multiple nozzles to achieve uniform cooling, maintaining cooling rate consistency while simplifying the device structure and ease of operation.
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 approach achieves rapid and uniform vitrification of the sample, preventing ice crystallization and maintaining the sample in an amorphous state, thereby improving the quality of cryogenic samples for study in charged particle microscopes.
Implementation Method 1
a flow of cryogenic fluid is provided out of said first nozzle in such a way that the sample is cryogenically cooled
Implementation Method 2
achieves rapid and uniform vitrification of the sample, preventing ice crystallization
Data Source
Figure 1A
Figure 1B~2
Figure 3A
AI summary
The invention relates to a method and an apparatus for preparing a cryogenic sample, whereby the sample is subjected to rapid cooling using a cryogen. The method comprises the step of providing a sample, said sample comprising a specimen provided on a substantially planar specimen carrier. The method comprises the step of providing at least one flow device for transporting cryogenic fluid to said sample, wherein said flow device comprises a first nozzle for directing a flow of cryogenic fluid onto said sample. Then, the sample is positioned next to said first nozzle and a flow of cryogenic fluid is provided out of said first nozzle in such a way that the sample is cryogenically cooled. As defined herein, the nozzle opening of the first nozzle has a width, as measured in a first direction, and a height, as measured in a second direction substantially perpendicular to said first direction, wherein said width is larger than said height. Using a non-circular, such as essentially oval or rectangular nozzle opening provides for more improved cooling, so that all parts of the specimen carrier are evenly cooled.