Mind the Bend: Curved and Corrugated Cryo-Lamella for Improved Mechanical Resilience
Preparing electron-transparent cryo-lamellae is inherently a serial, low-throughput process. During sample handling, milling, and transfer, cryo-fixed cells and their supporting films are subjected to mechanical forces as well as thermal stresses caused by temperature fluctuations. After milling, these extremely thin lamellae remain vulnerable to both mechanical and thermal stress, often leading…
Preparing electron-transparent cryo-lamellae is a laborious, step-by-step process susceptible to mechanical forces and thermal stresses. These forces often result in lamellae cracking or disintegrating, leading to the loss of valuable specimens. Typically, these fragile lamellae are flat, making them prone to bending during the milling process. This unintentional bending complicates the final polishing step for uniform thinning.
To tackle this issue, researchers propose creating lamellae with a pre-bent arch shape instead of the usual flat design. The arch geometry is inherently more stable and less likely to fail under mechanical stress. Furthermore, pre-bent milling patterns allow for more uniform thinning of bent lamellae, a challenge with traditional flat milling methods.
The researchers also explore corrugated lamellae, characterized by a sinusoidal variation around the flat lamella plane. This design offers increased mechanical stability compared to traditional flat lamellae.
The team fabricated a series of lamellae with both arches and corrugations. Using high-resolution cryo-TEM imaging, they demonstrated that non-flat geometries do not hinder cryo-electron tomography performance. To gain further insight into stress distributions within bent and corrugated lamellae, they conducted finite element method (FEM) simulations.
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