A wet stage modification to a scanning electron microscope

Area of Science:

• Materials Science
• Microscopy
• Biology

Background:

• Traditional scanning electron microscopy (SEM) requires samples to be dehydrated, limiting the study of biological specimens in their native states.
• Observing hydrated biological samples necessitates specialized techniques to maintain sample integrity under vacuum conditions.

Purpose of the Study:

• To modify a JSM2 scanning electron microscope (SEM) to accommodate hydrated specimens within its vacuum system.
• To enable high-resolution surface topography imaging of biological samples in a water vapor environment.

Main Methods:

• A modification was made to the vacuum system of a JSM2 SEM to introduce water vapor up to 1.3 kPa (10 Torr).
• Hydrated specimens were placed inside the specimen chamber and surrounded by water vapor.
• Surface topography was observed using a wide-angle backscattered electron detector in normal scanning mode.

Main Results:

• The modified SEM successfully imaged hydrated biological specimens partially immersed in water.
• A resolution of approximately 0.2 µm was achieved for biological specimens at temperatures just above 0°C.
• The technique retained the characteristic depth of focus of SEM imaging.

Conclusions:

• The vacuum system modification allows for the examination of hydrated biological specimens in a SEM.
• This method provides high-resolution surface topography imaging of wet samples, preserving their natural state.
• The technique is suitable for studying biological samples under near-physiological conditions.