Fast Sample Switching Mechanism for Atmospheric Scanning Electron Microscopy and Electron Beam Irradiation Systems of Living Cells

Abstract

Atmospheric scanning electron microscopy is a technique that enables high-resolution imaging of living specimens and targeted irradiation of specific regions of interest in the sample. To produce a highly focused electron beam, a high vacuum is required inside the electron gun column. However, living specimens need to be maintained at atmospheric pressure to survive. To enable interaction between the sample and the electron beam, the sample is placed on a thin silicon nitride window, which forms the barrier between the vacuum and the atmosphere with minimal scattering of the electron beam. This allows for the imaging of the specimen through the window surface. We have developed a mechanism that allows for fast switching between the samples while the system is under operational pressure. Timing is crucial in the case of living specimens because wet samples undergoing a lengthy preparation process may dry prematurely. Typically, changing between samples can take around one hour or longer because each time, the electron gun column has to be re-pressurized and evacuated again. Our system allows for changing between samples within seconds with excellent pressure stability. We have successfully introduced and tested a hand-operated, low-cost, and scalable solution by utilizing a rotary turret system with a customized bearing arrangement and an innovative approach to standard O-ring seals.