Sample supports and sample cooling systems for cryo-electron microscopy
The invention is directed to a sample support design and sample cooling devices for single-particle cryo-electron microscopy that simplify sample preparation and handling, dramatically reduce errors and improve outcome reproducibility, and dramatically reduce overall costs. A system includes a grid based sample support system, grid handling tools, grid blotting tools, a plunge cooling system, and jet cooling systems.
1. A sample support device, comprising:
a grid having a first surface, a second surface, a grid thickness, an inner portion, and an outer portion, the inner portion including a plurality of grid bars defining a plurality of holes through the first and second surfaces in between the grid bars, the plurality of holes having a first diameter; and
a sample support film in contact with the first surface of the grid, the sample support film having a film thickness less than the grid thickness, the sample support film also defining a plurality of apertures extending through the sample support film and including a second diameter smaller than the first diameter of the plurality of holes in the grid,
wherein the grid includes a first metallic material having a first thermal conductivity and a first electrical conductivity, and the sample support film includes a second metallic material having a second thermal conductivity and a second electrical conductivity less than the first thermal conductivity and the first electrical conductivity, respectively, such that, during cooling of the sample support device with a cryogenic fluid, the second thermal conductivity of the sample support film inhibits heat transfer from the grid bars to the sample support film while allowing the sample support film in the holes defined by the grid bars to cool faster than the grid bars.
2. The sample support device of claim 1 , wherein the second metallic material includes a metal alloy of chromium and gold with a chromium content of between 0.1% and 10%.
3. The sample support device of claim 1 , wherein the second thermal conductivity of the second metallic material is 1/10 the first thermal conductivity of the first metallic material.
4. The sample support device of claim 1 , wherein the grid thickness is between 10 micrometers and 25 micrometers.
5. The sample support device of claim 1 , wherein the film thickness is between 10 nanometers and 100 nanometers.
6. The sample support device of claim 1 , wherein the grid bars form a mesh with 200 to 400 cells per linear inch.
7. The sample support device of claim 1 , wherein the second diameter of the apertures in the sample support film is between 0.5 micrometers and 2.0 micrometers.
8. The sample support device of claim 1 , wherein the sample support film has a solid overlap region having no through-holes and overlapping the grid bars and within a region adjacent to the grid bars.
9. The sample support device of claim 8 , wherein the solid overlap region of the sample support film includes a region adjacent to the grid bars with a width of about 5% of a grid bar width or at least two times the first diameter of the holes in the grid.
10. A sample support device, comprising:
a grid having a first surface, a second surface, a grid thickness, an inner portion, and an outer portion, the inner portion including a plurality of grid bars defining a plurality of holes through the first and second surfaces in between the grid bars, the plurality of holes having a first diameter; and
a sample support film in contact with the first surface of the grid, the sample support film having a film thickness less than the grid thickness, the sample support film also defining a plurality of apertures extending through the sample support film and including a second diameter smaller than the first diameter of the plurality of holes in the grid, wherein the sample support film further includes a first film region with a first film thickness and a second film region with second film thickness distinct from the first film thickness.
11. The sample support device of claim 10 , wherein the first and second film regions of the sample support film both include the apertures.
12. The sample support device of claim 11 , wherein an outer periphery of the sample support film is thicker than an inner region of the sample support film.
13. The sample support device of claim 12 , wherein the outer periphery of the sample support film is aperture-free.
14. The sample support device of claim 10 , wherein the first thickness of the first film region is between about 10 nm and about 100 nm.