Dr Sergei Rouvimov, Associate Research Professor in the Department of Electrical Engineering and Transmission Electron Microscopy Program Director for the Notre Dame Integrated Imaging Facility passed away on May 29, 2020 after battling ALS for over a year. Sergei earned a PhD in physics from A. F. Ioffe Institute (St-Petersburg, Russia) and held research positions in Germany and Russia before moving to the Lawrence Berkeley National Laboratory, in California, USA. His long and productive career in the USA included periods in industry (SUMCO Phoenix Corporation) and academia (Portland State University). He was recruited to the University of Notre Dame in 2012, where he created a world class, multimillion dollar Transmission Electron Microscopy research facility that solved a wide range of research problems in advanced materials, nanotechnology and metrology. As a world recognized expert in Transmission Electron Microscopy he founded the annual Midwest Imaging and Microanalysis Workshop, a meeting of regional leaders in the field, and the Notre Dame Electron Microscopy Club, which catered to graduate students and early career researchers. Sergei was a brilliant and rigorous researcher and an expert on all matters concerning electron microscopy. He collaborated with a large number of campus engineering and science research groups and he was the author or co-author of many outstanding international research publications and book chapters. He was passionate about teaching and student training, and one his many legacies is a large number of superbly trained electron microscopists who are now pursuing independent careers. His technical expertise, passion for microscopy research, sense of humor, and warm collegiality will be greatly missed. Deepest condolences are offered to his wife, Maria Mikhailova and daughter, Anastasia Ruvimova. In lieu of flowers, please consider a donation to the ALS Association.