Location: Medical Sciences Building, E-5B
|UIC Cost||$15.30 (per hour)||$61.20 (per hour)|
|Other Academic||$24.60 (per hour)||$96.60 (per hour)|
|Non-Academic;||$85.20 (per hour)||$190.20 (per hour)|
There are many ways of preparing specimens for electron microscopy. The EMS staff are available to help investigators determine the best way of getting the information they need from their specimens. The following is intended only as a general guideline.
The size of the SEM specimen depends on which instrument you need for your analysis. The Hitachi S-3000N is able to accept specimens up to 150mm in diameter (although parts of the specimen cannot be accessed). The JEOL JSM-6320F can accept specimens up to 30mm in diameter and 10mm high. In general, however, the amount of material should be kept as small as possible, especially if it is non-conducting. Conducting specimens can be imaged in both SEMs without any further specimen preparation. Non-conducting specimens may need coating with a conducting film in order to reduce charging at high vacuum in all microscopes. The EMS is able to coat with either carbon, platinum/gold, platinum/palladium or, for high resolution imaging, chromium. In low vacuum mode (S-3000N only) it is not necessary to coat any specimen and some non-conducting specimens can be imaged without charging at low voltage (S-3000N, JSM-6320F).
All EMS TEMs take standard size specimens (3mm in diameter). The maximum thickness of the specimen depends on the density of the specimen. The EMS has extensive specimen preparation facilities to convert bulk material into transmission thin samples of the correct diameter. Life Science Specimens are supported on a grid or a slotted 3mm washer. Life Science specimens are typically prepared using an ultra-microtome to cut slices less than 100nm thick which can then be supported on a grid.
All life science specimens (for SEM or TEM) need to be processed to remove the water from the specimen and replace it with a plastic resin without introducing artifacts. Typically, for TEM, this is a multistage process involving
- Fixation - to halt degradation of tissue
- Dehydration - to replace water with ethanol and then a transitional solvent
- Infiltration - to impregnate the specimen with resin
- Embedding - to enclose the resin impregnated specimen in more resin
- Ultramicrotomy - to cut transmission thin slices from the specimen
- Staining - to increase the contrast of the images obtained by staining parts of the structure with a heavy metal stain (eg uranyl acetate)
Equipment available in the EMS-W prep lab includes:-
- Sputter coaters for depositing metal films (Cressington 208HR (Cr) and Polaron E5100 (Pt/Pd & Au/Pt)).
- Carbon Coater (Edwards E306A)
- Tissue Rotator (EMS), Centrifuge (Spectrafuge 6C)
- various Ovens
- Glass Knife Maker (LKB 7801B)
- Ultramicrotomes (Leica Ultracut UCT and Reichart Ultracut E)
- Leica Automatic Freeze Substitution (AFS)
- Reichart Metal Mirror Cryofixation System (MM80E) and Universal Cryofixation System (KF80)