A diamond knife is a very sharp knife in which the edge is made from

diamond Diamond is a Allotropes of carbon, solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Another solid form of carbon known as graphite is the Chemical stability, chemically stable form of car ...

, invented by Humberto Fernández-Morán in 1955. Diamond knives are used for medical and scientific applications where an extremely sharp and long-lasting edge is essential. The knives are very expensive to purchase, depending on the quality and size of the knife; in addition the knives must be professionally sharpened as the edge dulls.

Eye surgery

Diamond knives are used in

eye surgery Eye surgery, also known as ophthalmic or ocular surgery, is surgery performed on the eye or its adnexa, by an ophthalmologist or sometimes, an optometrist. Eye surgery is synonymous with ophthalmology. The eye is a very fragile organ, and requ ...

, specifically in

refractive surgery Refractive eye surgery is optional eye surgery used to improve the refractive state of the eye and decrease or eliminate dependency on glasses or contact lenses. This can include various methods of surgical remodeling of the cornea (keratomileu ...

. In particular they are the main tool, together with the microscope, for the radial keratotomy invented by

Svyatoslav Fyodorov Svyatoslav Nikolayevich Fyodorov (; August 8, 1927 – June 2, 2000) was a Russian ophthalmologist, politician, professor, full member of the Russian Academy of Sciences and Russian Academy of Medical Sciences. He is considered to be a pioneer of ...

to correct myopia and for the Mini Asymmetric Radial Keratotomy (M.A.R.K.), invented by Marco Abbondanza to correct astigmatism and cure the first and second stages of keratoconus.

Ultramicrotomy

Metal microtome knives or razor blades are too soft and dull to cut ultrathin sections. In 1950, Latta and Hartmann discovered that the edge of broken glass could be used to cut thin sections of specimens for

transmission electron microscopy Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a g ...

. Glass knives are used in

ultramicrotomy Ultramicrotomy is a method for cutting specimens into extremely thin slices, called ultra-thin sections, that can be studied and documented at different magnifications in a transmission electron microscope (TEM). It is used mostly for biological spe ...

for trimming specimen blocks and cutting thin and ultrathin sections. A skilled operator can cut a small number of ultrathin sections with a glass knife, while the same operator can use a diamond knife to cut thousands of sections on one area of knife. Some hard specimens, such as bone, plants, thick-walled spores, metals and ceramics are difficult to cut, even with a good glass knife, because the edge dulls too quickly. Humberto Fernández-Morán discovered that a gem-quality diamond, the hardest known material, could be used to fabricate a more durable knife for use in the ultramicrotomy. Diamond knives are both delicate and expensive, usually costing several thousand dollars. Natural gemstones used to produce diamond knives are usually pale yellow, of regular crystal structure and of the greatest possible purity. The grinding process usually reduces the stones to 50% of their original weight. The diamond blade is then mounted into a soft metal shaft (

Wood's metal Wood's metal, also known as Lipowitz's alloy or by the commercial names Cerrobend, Bendalloy, Pewtalloy and MCP 158, is a metal alloy that is useful for soldering and making custom metal parts, but which is toxic to touch or breathe vapors from. ...

) and finally polished to a very sharp edge. The knife's edge is extremely sharp and free of imperfections, which helps produce ultrathin sections of very regular thickness to get views of specimens at high magnifications with the

transmission electron microscope Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a gr ...

(TEM).Micro Star Technologies, diamond knives
The shaft containing the final edge is then mounted in a metal trough, or "boat", and cemented, usually with an epoxy plastic. Diamond knives are also used for specimen preparation in

atomic force microscopy Atomic force microscopy (AFM) or scanning force microscopy (SFM) is a very-high-resolution type of scanning probe microscopy (SPM), with demonstrated resolution on the order of fractions of a nanometer, more than 1000 times better than the op ...

Types

There are many styles and types of diamond knives. For the most part, they can be made for use dry or wet. Blade angles of diamond knives vary from 35 to 60 degrees. The smaller angled knives are used for finer cutting, but these knives are prone to damage. Wide angle knives have better life expectancy.

References

{{Reflist Knives Diamond

Eye surgery

Ultramicrotomy

Types

See also

References