The aim of this program is to develop an inexpensive, durable, ultra- sharp knife blade for use in microtomes. The knife will be 5 mm long and made of silicon. It will be made with the same basic approach used in semiconductor chip manufacturing with selected process steps researched and developed as needed. This type of processing/manufacturing results in product with very low unit cost. The technological innovation of this proposed device lies in the degree of sharpness, durability and low cost of the knife compared with existing microtome technology using glass, diamond or steel blades. The sharpness is the maximum possible since the edge is expected to consist of only a few atoms with a "radius of curvature" less than 0.5 nm, and a smaller radius is essentially meaningless. The durability derives from both the hardness and the room-temperature diffusion characteristics of silicon: silicon, steel and glass have comparable hardness, and silicon does not exhibit the type of surface flow that dulls a newly-formed glass knife after a few days. The combination of properties expected in this technologically innovative knife (ultra-sharp, durable, disposable, very low manufacturing costs) are expected to have positive impact on a wide spectrum of health-related programs dependent on microscopic examination of tissue. The advantages offered by these same properties together with the known use of the microtome as a standard instrument in clinical and research laboratories worldwide argue for its development and commercial exploitation.Proposed commercial application:Application as an ultra-sharp knife for microtomes and surgical blades.National Institute fo General Medical Sciences (NIGMS)