The 2026 environmental transmission electron microscope roadmap

Abstract

Environmental Transmission Electron Microscopy (ETEM) has emerged as a powerful technique for real-time atomic-scale observation of materials under reactive gas or liquid environments, overcoming the vacuum limitations of conventional TEM. However, reconciling high-resolution imaging with the maintenance of realistic environmental conditions around the sample remains a fundamental challenge. Two primary technological pathways, differential pumping systems (DPS) and windowed cells, have been developed to address this trade-off, each with distinct advantages and limitations in terms of achievable pressure and resolution. Despite significant advances, including the use of spherical aberration correctors and two-dimensional material-based windows, challenges such as the “pressure gap”, electron beam effects, and the complexity of multi-physical field integration persist. Research in this field is extremely active, focusing on next-generation reactor designs, artifact mitigation, and correlation with advanced spectroscopy and machine learning. With the myriad of technologies and their associated challenges, we were motivated to assemble this roadmap to outline a comprehensive framework for ETEM development.