Cryo-EM Sample Support Foils With Auxetic Slots for Stress Relief
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Solution Overview
Problem
Current cryo-electron microscopy sample preparation and handling methods are fraught with issues such as grid and foil damage, imprecise sample thickness control, biomolecule denaturation, and beam-induced sample motion, which limit resolution and throughput.
Innovation Solution
Innovative sample support designs and cooling devices for cryo-electron microscopy, including grids with solid gripping regions, mechanically isolated interior areas, stress-relieving foil patterns, and automated grid handling tools, to reduce grid and foil damage and beam-induced motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual handling of grids and foils is used, then ease of operation is maintained, but grid damage and reliability deteriorate
Solution Approach 1:
The grid is segmented into distinct functional zones: a sample preparation area with the foil and a separate gripping area with solid metal regions. This segmentation allows automated grippers to handle the grid by its edges without contacting the fragile foil, eliminating manual handling while preventing grid damage and maintaining reliability.
2Ease of operation
If conventional sample dispensing and blotting is used, then ease of operation is maintained, but manufacturing precision deteriorates
Solution Approach 1:
The manual mechanical process of dispensing and blotting is replaced with an automated mechanical system. A blotting paper is automatically positioned and pressed against the grid to remove excess sample, providing controlled and repeatable film thickness without requiring manual skill, thus improving manufacturing precision while maintaining ease of operation.
3Speed
If rapid plunge cooling is used, then cooling rate is improved, but sample motion and information loss worsen
Solution Approach 1:
The grid is pre-cooled to cryogenic temperatures before sample application. This preliminary cooling action establishes a cold baseline that reduces thermal gradients during subsequent plunge cooling, minimizing sample motion and information loss while maintaining the necessary rapid cooling rate for vitrification.
Solution Approach 2:
A support film or mesh is introduced as an intermediary between the sample and the grid structure. This intermediary provides mechanical stability to the sample during rapid plunge cooling, reducing beam-induced motion and information loss while allowing the rapid cooling rate to be maintained for proper vitrification.
4Reliability
If solid gripping regions are added to grids, then reliability improves, but device complexity worsens
Solution Approach 1:
The solid gripping regions serve multiple functions: they provide structural reinforcement to the grid, create dedicated zones for automated gripper contact, and define the boundaries of the sample preparation area. This multi-functionality improves reliability without significantly increasing device complexity, as the gripping regions are integrated into the existing grid structure.
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
Enhances sample cooling rates, reduces grid and foil damage, and facilitates more controlled sample preparation and automated storage, thereby improving imaging resolution and throughput in cryo-EM.
Implementation Method 1
foil stress in those interior areas created during assembly of the foil and the grid/manufacturing and that may arise due to differential contraction of foil and grid during cooling to cryogenic temperatures
Implementation Method 2
auxetic patterns
Implementation Method 3
To vitrify the buffer for the best imaging, the sample-containing foil-and-grid assembly is plunged at 1-2 m/s into liquid ethane at T ̃90 K
Implementation Method 4
the sample-containing foil-and-grid assembly is plunged at 1-2 m/s into liquid ethane at T ̃90 K
Implementation Method 5
liquid ethane at T ̃90 K (produced by cooling gas in a liquid-nitrogen-cooled cup)
Data Source
AI summary
Presented are sample-supporting foils and grids for cryo-electron microscopy (cryo-EM) systems, methods for making/using disclosed cryo-EM foils, grids, devices, and/or systems, and cryo-EM systems equipped with disclosed foils, grids, and/or devices. A sample-support grid assembly may include a grid body with opposing first and second grid surfaces and multiple grid holes extending through the grid body from the first grid surface to the second grid surface. A foil sheet is seated against the first surface and covers at least a subset of the grid holes in the grid body. The foil sheet includes multiple foil regions filled with foil holes and separated from each other by multiple elongated slots. These elongated slots enable the foil regions to move with respect to each other when the grid assembly is under load. The slots of the foil sheet may be arranged in an auxetic pattern.