How it began
Humberto Fernández-Morán, a physician born in Maracaibo in 1924, trained in Munich and Stockholm, where he began to conceive of a diamond blade for ultramicrotomy. He returned to Venezuela in 1953 and promoted the Venezuelan Institute for Neurological and Brain Studies, funded in 1954, which began research in December 1955 and included a diamond blade workshop. A biographical paper dates the knife to 1953, when he published it, while the U.S. National Library of Medicine, which holds his papers, dates the invention to 1955.
Before it existed
Thin sectioning for the electron microscope relied on glass. In 1950 Harrison Latta and Francis Hartmann found that the edge of broken glass could cut thin sections. Glass edges dulled quickly, and hard specimens such as bone, plants, thick-walled spores, metals and ceramics were difficult to cut even with a good glass knife.
How it works
The knife has an edge made from diamond that is extremely sharp and free of imperfections, so it produces ultrathin sections of regular thickness and keeps its edge. Fernández-Morán designed an ultramicrotome to take advantage of it. The instrument advances the specimen past the fixed knife in very small steps, and in 1957 he combined the two with cooling in a cryo-ultramicrotome. The thin sections improved resolution and focus in the transmission electron microscope.
How it spread
For many years diamond knives produced in Venezuela were supplied free of charge to any researcher in the world who asked for them. Fernández-Morán left Venezuela in 1958, after the fall of the government in which he had served as minister of education, and worked at the University of Chicago. In 1967 he received the John Scott Award for the diamond scalpel. He used diamond knives to make ultrafine cuts in lunar samples for NASA's Apollo program.
Where it stands today
Diamond knives are used in medicine and science wherever a very sharp and long-lasting edge is needed. They are common in eye surgery, where they leave smoother incisions, and remain standard tools for preparing sections for electron microscopy. They are expensive and must be resharpened professionally as the edge dulls. The institute Fernández-Morán founded became the Venezuelan Institute for Scientific Research (IVIC).
