TEM Vacuum Transfer Assembly for Ice-Free Cryosample Handling
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Solution Overview
Problem
Current cryotransfer systems in microscopy are expensive, user-unfriendly, and prone to specimen degradation due to ice formation, with limited capability for in-situ experiments and poor vacuum maintenance, especially when handling air-sensitive samples and large samples.
Innovation Solution
A redesigned vacuum transfer assembly with a sample holder stage and vacuum housing that allows for controlled, vacuum-sealed transfer of samples, maintaining ultra-high vacuum conditions and enabling in-situ experiments at low temperatures, featuring a wider sample rod for better cooling and additional stimuli application, and an integrated α-tilt system within the holder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complete cryotransfer system with integrated TEM and permanently fitted sample holder is used, then cryotransfer capability is achieved, but the system becomes expensive and lacks versatility for in-situ experiments
Solution Approach 1:
The system is divided into separate functional modules: a removable sample holder that can be transferred between different microscopes, a vacuum housing that maintains ultra-high vacuum, and a coupling unit that enables versatile connections. This segmentation allows the same sample holder to be used for cryotransfer in TEM and for in-situ experiments in other microscopes, achieving both reliability and versatility without requiring a permanently integrated expensive system.
2Weight of moving object
If a small valve is used in the Dewar to keep holder weight acceptable, then weight is reduced, but vacuum pumping speed becomes limited
Solution Approach 1:
Instead of increasing valve size in the traditional vertical direction which would increase weight, the system adds a second valve at a different location (another dimension in the holder structure). This allows dual-path vacuum pumping capability without significantly increasing the weight of individual components, thereby achieving high pumping speed while maintaining acceptable holder weight.
3Object-affected harmful factors
If a sliding mechanism with airtight seal is used to push sample into sealed space, then sample protection is achieved, but the sealed area becomes small and cannot accommodate sensors
Solution Approach 1:
The sealed space is segmented into multiple zones with multiple airtight seals at different locations. This creates several smaller sealed compartments rather than one large sealed area, allowing sensors and other components to be placed in specific zones while maintaining protection for the sample in other zones. The coupling unit further segments the connection interface to accommodate various sensor types.
4Ease of operation
If the sample holder is transferred through air to allow insertion into TEM, then accessibility is improved, but vacuum conditions deteriorate and ice formation occurs on sample
Solution Approach 1:
The sample holder is pre-cooled to cryogenic temperatures before transfer, and the vacuum housing is pre-evacuated to ultra-high vacuum conditions. During transfer through air, the sample remains protected inside the pre-cooled holder with minimal exposure. The rapid insertion into the pre-prepared vacuum environment minimizes ice formation and maintains sample integrity, achieving both ease of operation and reliability.
5Temperature
If a wider sample rod is used for better cooling and additional stimuli application, then cooling capability and experimental capability are improved, but the holder diameter increases affecting vacuum maintenance
Solution Approach 1:
The holder structure is segmented into the sample rod and the outer housing. The sample rod can be optimized for cooling capability with appropriate diameter, while the outer housing provides the vacuum seal. This segmentation allows the sample rod to be wider for better cooling and stimuli application without proportionally increasing the overall holder diameter, thereby maintaining better vacuum conditions.
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
Facilitates easy cryotransfer of cryosamples without ice formation, maintains ultra-high vacuum in the TEM, and allows for longer experimental durations with improved mechanical stability and resolution, enabling larger sample handling and additional experimental capabilities.
Implementation Method 1
maintaining ultra-high vacuum conditions
Implementation Method 2
a cooling rod inside the holder, which transports 'coldness' to the tip of the rod
Data Source
AI summary
The present invention is in the field of a vacuum transfer assembly, such as for cryotransfer, and specifically a TEM vacuum transfer assembly, which can be used in microscopy, a sample holder, a vacuum housing, a sample holder stage and a sample holder coupling unit for use in the assembly, and a microscope comprising said assembly as well as a method of vacuum transfer into a microscope.