Cryogenic Cooling of Biological Samples for Electron and Optical Microscopy
Cryogenic liquid transfer systems have proven to be the method of choice for most cooling applications for spectrophotometric studies. The application of such methods to biological systems requires a few modifications. The cryogenic systems can operate in any position but most liquid samples must be placed in cuvettes in the vertical position from the top. Temperature control from 77K to room temperature can be accomplished using a liquid nitrogen supply, a 20 ohm strip heater, a silicon diode transducer and an automatic temperature controller.
Various designs are presented with limited test data, where standard cuvettes are mounted on OHFC copper in a vacuum shroud necessary for the low temperature studies. Some suggested approaches to expanding the versatility of the systems are given. A unique application is the use of a vacuum cooled sample plate and injecting the test sample into the chamber through a rubber septum giving instantaneous cooling of the sample.
KeywordsRadiation Shield Cryogenic Cool Cold Finger Liquid Cryogen OFHC Copper
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