Capillary Cap Indent for Deformation-Free Sample Exposure
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Solution Overview
Problem
Existing methods for high-pressure freezing of aqueous solutions in capillaries face challenges such as deformation of sample material during capillary opening, low throughput due to metal removal processes, and inefficiencies in sample inspection and preparation, particularly due to ice crystal formation and crystallization issues.
Innovation Solution
A capillary assembly with a cap having an indent and a sharp needle end that fits into the capillary, allowing for the removal of the cap to expose a free-standing pillar of frozen sample material, enabling inspection and machining without deforming the sample, and using a metal or ceramic capillary with a conical recess for efficient cooling and minimal material loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the metal capillary is opened by shaving with a microtome, then the sample material can be exposed for inspection, but the exposed sample material may be deformed due to forces exerted during metal removal
Solution Approach 1:
The invention divides the capillary system into separate components: an inner capillary containing the sample and an outer capillary providing structural support. The inner capillary can be removed independently from the outer capillary, allowing sample exposure without applying mechanical forces to the sample itself. This segmentation resolves the contradiction by enabling sample access (improving ease of operation) while protecting sample integrity (maintaining manufacturing precision).
Solution Approach 2:
The invention extracts the sample-containing inner capillary from the outer capillary structure. By removing only the necessary outer capillary portion or the entire outer capillary while leaving the inner capillary intact, the sample can be accessed without subjecting it to deforming forces. This extraction approach allows sample exposure while preserving sample geometry.
2Manufacturing precision
If the metal capillary is removed using an ion beam, then the sample can be inspected without deformation, but the milling rate of metal is relatively low and it takes long to expose sample material
Solution Approach 1:
By segmenting the capillary structure into removable inner and outer components, the invention eliminates the need for slow ion beam milling of solid metal. The outer capillary can be quickly removed mechanically or by simple machining, exposing the sample rapidly while maintaining precision. This segmentation resolves the productivity bottleneck of ion beam processing.
Solution Approach 2:
The invention replaces the slow mechanical process of ion beam milling with a faster mechanical removal approach. Instead of using ion beams to gradually erode metal, the outer capillary is designed to be easily removed through simple mechanical means, significantly reducing exposure time while maintaining sample integrity.
3Ease of manufacture
If a cellulose or polymer capillary is used inside the metal capillary, then the aqueous solution can be contained, but a large part of the already small volume of the metal capillary is filled with non-sample material
Solution Approach 1:
The invention extracts the inner capillary containing the aqueous solution from the outer metal capillary after freezing. By removing the outer capillary structure, the sample volume is maximized and no longer constrained by the outer capillary's internal volume. This extraction allows the sample to occupy the full available space without being displaced by outer capillary walls.
Solution Approach 2:
The invention uses a nested structure where the inner capillary is placed within the outer capillary during the freezing process. This nesting allows for easy containment and handling during manufacturing and freezing, while the subsequent removal of the outer capillary maximizes the effective sample volume, resolving the contradiction between ease of manufacture and sample quantity.
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 method allows for higher throughput and minimizes sample deformation by exposing the sample material for inspection and machining at cryogenic temperatures, maintaining amorphous state and avoiding crystallization, thus improving the efficiency and quality of sample preparation and analysis.
Implementation Method 1
rapidly cooling a thin sample, but a cooling rate in excess of 10 4 K/s is required
Implementation Method 2
the aqueous solution is frozen at a high pressure to form an amorphous frozen sample
Implementation Method 3
amorphous ice is stable at a temperature below the glass transition temperature of water, which is approximately 135 K
Data Source
Figure 1A~1B
Figure 2a~2b
Figure 3~4
AI summary
Assembly of cooperating capillary (1) and cap (2) for containing an aqueous solution (3) in an inner volume of the capillary, the assembly equipped to be used in a high pressure freezer in which the aqueous solution is frozen at a high pressure to form an amorphous frozen sample at a cryogenic temperature, the inner volume of the capillary having a diameter of less than 500 µm, preferably less than 350 µm, and the cap equipped to form a closure to one end of the capillary, characterized in that the part of the cap that is in contact with the inner volume of the capillary when the cap forms a closure, shows an indent, as a result of which the cap, after freezing the aqueous solution, can be removed from the capillary and a free standing pillar of frozen aqueous material extends from the capillary. As a result of this the metal of the capillary need not be cut and related artifacts are eliminated. Further inspection is preferably done using a focused ion beam forming block-face or lamella and an electron beam for the inspection of the sample.