For SEM imaging there are a number of considerations when preparing sample.
Materials need to be able to withstand the vacuum inside the specimen chamber. Thus samples need to be dry and have sufficient strength/rigidity. Particular care need be taken with biological samples in this regard (see additional notes).
Samples need to be electrically conductive in order to prevent the negatively charged electrons from building up on the sample. Where material is not conductive a fine layer of a conductive medium is first coated on the surface (typically gold).
Sample size should be kept to a minimum especially where coating is required.
AAC staff can help/advise on all aspects of sample preparation.