Many biological events occur at a small number of specific sites within a very large volume. It has recently been shown that focused ion beam (FIB) technology is useful for exposing biological structures for examination. In addition, it has been shown that biological material can be removed using FIB without detectable collateral damage beyond 100Å in fixed, dehydrated, critically point dried tissue.The next step in determining the practical utility of FIB for removal of material from a representative tissue block is to demonstrate that relevant biological structure can be exposed at a selected site. A cross sectioning technique, commonly used for analysis of semiconductor devices, was employed to demonstrate this capability on a block of rat liver prepared as above for SEM. A contiguous-series of successively deeper rectangles are cut into the material using a relatively large, high current beam (0.18μm diameter, 1nA), removing a wedge of material and leaving a large exposed face perpendicular to the surface. The exposed face can then be examined by tilting the sample and viewing with either the FIB or by SEM.
High brightness inductively coupled plasma source for high current focused ion beam applications