Increasing the versatility of an EMscope SP2000A sputter cryo system on a Hitachi S‐570 scanning electron microscope

Abstract

AbstractThe EMscope SP2000A Sputter Cryo System provides biologists with a quick and reproducible procedure to freeze, fracture, etch, and sputter coat biological samples, which are then transferred to a cold stage for scanning electron microscopic (SEM) observations. The standard specimen holder, which is supplied with the unit and referred to as a “stub,” will accommodate most specimens; however, fabricating a variety of additional holders to perform more specialized functions considerably increases the versatility of the cryounit and the resolution that can be achieved. For example, the adaptation of small hinged or hingeless gold holders, which are used in the freeze‐fracture technique, produces clean fractures, allows for storage of samples in liquid nitrogen and permits samples to be frozen much more rapidly than the large standard holder. A short working distance holder has been designed, which allows samples to be inserted into the final objective lens, thereby resulting in a negative working distance up to −3 mm. Use of this holder with the upper detector in the Hitachi S‐570 SEM, enhances the secondary electron signal and thereby increases resolution of frozen samples severalfold. Another specimen holder has been designed, which allows conventional SEM stubs to be observed without removal of the cryostage. This modification permits use of the EMscope stage and specimen transfer device at room temperature without any further alteration or adjustment. These and other types of modified holders allow investigators to store, manipulate, fracture, and observe biological samples at resolutions not normally attainable with a standard SEM cryostage.