Cryo-electron microscopy (CryoEM) has become an essential tool for determining the structures of small biomolecules, such as proteins, viruses, and DNA. Despite the advancements in CryoEM, the design of the sample carrier (grid) has remained largely unchanged. However, microfabrication techniques, driven by the semiconductor industry, have made significant progress. In this abstract, we present a silicon-based sample carrier using microfabrication techniques to address the limitations of traditional grids.
Conventional grids are made from soft metals like copper or gold, typically covered with a holey carbon film. While these materials have desirable thermal conductivity, they are fragile and prone to bending, requiring careful handling during clipping and loading into autogrids. Furthermore, their surfaces are often uneven, making sample preparation challenging, particularly in cryo-tomography. The carbon film often leads to inconsistencies in surface properties even within the same batch. Similarly, these sample carriers are typically suffering from very long lead times.
Our silicon-based carriers use nanotechnology and microfabrication techniques to overcome these limitations. These carriers consist of a silicon frame, a holey silicon nitride membrane, and a monolayer graphene layer. Silicon provides a rigid and robust frame, making handling and sample preparation easier. The carriers are fully autoloader compatible, allowing users to seamlessly integrate them with conventional metallic rings and C-clips. The growth of silicon nitride on a silicon substrate results in a highly reproducible, atomically flat surface, and microfabrication allows precise control of material properties, enhancing robustness. Furthermore, our developed microfabrication process ensures that the Graphene covers the entire wafer, enabling a high level of scalability and reproducibility.