Enabling Tailored In Situ Electron Microscopy Studies at Low Temperature

Journal article, 2025

In situ transmission electron microscopy (TEM) in combination with high-resolution imaging, diffraction, and spectroscopy enables real-time observation of dynamic processes at the atomic scale and the correlation between site-specific atomic structure and properties. The in situ techniques include the application of external stimuli such as temperature, electrical biasing, mechanical strain, and reactive environments. Traditionally, these experiments rely on specialized TEM holders, making the integration of multiple excitations challenging. Recent advancements in micro-electromechanical systems (MEMS) have enabled the development of in situ TEM chips giving access to experiments in both solid and liquid environments. By harnessing MEMS technology, we can design and fabricate chips that not only overcome the limitations of commercial solutions but also enable novel excitations, expanding the scope of in situ experiments. This work presents the principles of our MEMS chipdesign,fabricationanduseof2Dmaterialsemphasizingcustomizabilityto expand experimental possibilities. By leveraging nanofabrication techniques, we develop MEMS chips that allow innovative, multi-modal in situ studies while allowing scalable wafer-level fabrication. 2D materials exhibit intriguing electrical and optical properties that can be tuned through strain engineering. In situ biasing and straining experiments in scanning electron microscopes (SEM) and transmission electron microscopes (TEM) can reveal the mechanisms that are responsible for the changes in properties. The SEM and TEM studies require careful and advanced specimen preparation and manipulation of 2D flakes that are a few nanometers in thickness and extend a few micrometers. In addition, the 2D materials can be used to design the function of MEMS chips used for tailored in situ experiments.