Cryo-EM Sample Support Foil for Uniform Film Thickness
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Solution Overview
Problem
Current methods for preparing samples for cryo-electron microscopy face challenges in achieving uniform and controlled film thicknesses over a substantial area of the grid, leading to poor image quality and high costs due to manual handling issues, damage to grids and foils, and imprecise sample deposition.
Innovation Solution
The design of sample supports with regions of different thicknesses and the use of pillar arrays for controlled liquid deposition and removal, where the foil has step edges to pin contact lines and prevent surface-tension driven contraction, allowing for uniform film formation within the holes of the grid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manual blotting and evaporation methods are used to remove excess sample, then sample preparation can be performed with simple equipment, but film thickness control is imprecise and varies across the grid area
Solution Approach 1:
The invention changes the physical parameter of the support foil by creating regions of different thicknesses (e.g., 10 nm, 20 nm, 50 nm, 100 nm) to control the final film thickness. This allows precise control of sample film thickness without complex blotting procedures, as the varying foil thicknesses directly determine the ice layer thickness after vitrification.
Solution Approach 2:
The support foil is segmented into multiple regions with different thicknesses, each region producing a different final film thickness. This segmentation allows simultaneous preparation of multiple samples with different optimal thicknesses on a single grid, improving both precision and versatility.
2Manufacturing precision
If uniform film thickness is achieved across the grid, then image quality improves, but sample preparation time and cost increase due to complex procedures
Solution Approach 1:
The support foil structure performs the thickness control function automatically through its varying thickness regions. When sample is deposited and excess is removed by simple blotting, the foil thickness itself determines the final film thickness, eliminating the need for complex controlled procedures. The system serves itself by using the foil geometry to enforce uniform thickness within each region.
Solution Approach 2:
The thickness control is built into the support foil before sample deposition. The varying thickness regions are pre-formed on the foil, so when sample is applied, the final thickness is predetermined by the foil structure rather than requiring precise control during the deposition and blotting process.
3Ease of operation
If complex manual handling procedures are used for sample preparation, then sample deposition can be performed, but grids and foils are frequently damaged
Solution Approach 1:
The invention uses a support foil that can be manufactured at low cost with varying thickness regions. Even if the foil is damaged during handling, replacement is economical. The foil is designed to be consumed or replaced rather than preserved, allowing simple manual handling procedures without concern for damaging expensive components.
4Quantity of substance
If thicker sample films are used to ensure adequate particle distribution, then particle coverage improves, but particle image overlap increases reducing data quality
Solution Approach 1:
Different regions of the support foil have different thicknesses, allowing different particle concentrations to be optimized for different experimental needs. Some regions can be thicker for low-abundance samples, while other regions are thinner for high-abundance samples, with each region having locally optimized quality.
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 enables the production of uniform liquid films with controlled thicknesses between 10-150 nm over a significant area of the grid, reducing sample preparation time and costs, and improving the quality and throughput of cryo-EM data collection.
Implementation Method 1
the receding contact line of a liquid drop deposited on the foil is pinned by the step edge
Implementation Method 2
a pillar array is brought into contact with a foil of a cryo-electron microscopy sample support and withdrawn, thereby depositing liquid on the foil
Data Source
AI summary
Presented are systems, methods, and devices for provisioning sample support, controlled liquid deposition, and/or desired sample thicknesses during cryo-electron microscopy processes. A sample support for a cryo-electron microscopy process includes a support grid with multiple grid faces. The grid may be substantially rigid, flat and circular, may have a diameter of between about 2.9 and 3.1 mm, and may have a thickness of about 10 to 25 μm. A foil covers at least one of the grid faces and includes multiple foil regions that each has a distinct thickness. The foil may be a thin and flexible metal or carbon foil. At least one of the foil regions contains an array of through-holes. A boundary between the foil regions with distinct thicknesses forms a step edge that pins thereto a receding contact line of a liquid drop deposited on the foil.