Ceramic and Sapphire Knives

Created by Karen Darley, Modified on Fri, 24 May 2024 at 03:21 PM by Kathleen Patrick

Ceramic Zirconium blade

Sapphire blade

Ceramic and sapphire micro‐dissection knives (non‐metallic scalpels) were developed during the 1970s, subsequent to Fernadez Moran's invention of the first diamond knives (~1965) for ultramicrotomy and viewing specimens in electron microscopes. These diamond knives are used to produce flawless sections 60nm thick. This technology paved the way for hand‐held ceramic and sapphire micro‐knives for finest dissection and microsurgery. These knives were first used in ophthalmology, but they have proven useful in cosmetic surgery and microsurgery as well as in the biomedical sciences, whenever finest cuts, without reactive metal ions, and least adjacent cell damage are required.

Ceramic versus sapphire knives: Our ceramic knives are produced from black, sintered zirconium dioxide. This material is of similar hardness to sapphire, but it is not transparent and more flexible. Both the ceramic and sapphire blades are very hard, and considering how fine and acute the cutting edges are, they are surprisingly durable. The ability to see through a knife sometimes is an advantage, and the sapphires are glass‐clear. Sharpened edges usually reflect light away and so appear black with either blade. However, sapphire knives, when used near horizontal (the 'round blades' are particularly suitable) are excellent for cutting in that plane with perfect vision of structures below the knife.

Handling, cleaning and sterilising: Diamond (Mohs hardness scale 10), sapphire (9) and ceramic zirconia (8.5) are among the hardest substances known. Harder materials keep a sharp edge better. However, such hard materials may be brittle and lateral pressure on the knife can snap the stone. These knives must be handled with care and the cutting edge should only ever gently touch tissues to be cut and no other solid ‐ don't test the sharpness of our knives with a finger! If a blade is perfectly handled is can give years of good service, rough, but non 'fatal' handling of a knife will fracture microscopic particles off the knife's edges resulting in bluntness well before time.

After use rinse the knife under running water. If serious contamination occurred, the knife may be soaked in weak household detergent solution and placed in an ultrasonic bath for 2 minutes. Rinse in tap and then distilled water at least 3 times. The knives may be wet autoclaved. During these procedures make sure the actual knife never touches anything solid.

To prolong the life of this edge, never touch it with any solid object. Use the following guidelines: 

  1.  Avoid touching the edge when inserting or removing the knife. 
  2. Don't contact the edge with any tools when operating your microtome. 
  3. Safely store the blade in its box when not in use. 

The best sections come from a clean environment. Keep your knife clean by: 

  1. Using clean water, buffers or reagents in your microtome. 
  2. Rinsing and wiping the reservoir and stage of your microtome between use. 
  3. Preventing sections from drying on the knife. 

Sectioning problems usually come in three forms: 

Chatter, compression and knife marks. As a general rule, vibratome sectioning with a sapphire knife is done with high amplitude, slow approach speed and a knife angle setting of about 23°. You should spend some time learning the effects that changes in these operating parameters have on section quality. 

Chatter is the result of vibration during cutting and appears as regularly spaced thick and thin lines on the section perpendicular to the direction of cut. Too low a clearance angle, too fast an approach and too hard a specimen are several causes of chatter. 

Compression is a crushing of the section as it is cut, resulting in a section that is shorter than the original block face and thicker than the microtome setting. Too high a clearance, too soft a specimen and a dull knife can cause compression. 

Knife marks are lines that appear on the section parallel to the direction of cut. A dirty or damaged knife edge causes knife marks. 

If you have sectioning problems, especially knife marks, a dirty knife may be one of the causes. Clean the edge using a Diamond Knife Cleaning Tool, Product No. 122-10, following the steps on next page. This PVA spear tip wicks liquids instantaneously to make a safe and sure cleaning tool. The spear does not expand with alcohol so it can be used in its rigid form by dipping in reagent alcohol only: or it can be expanded using clean water and then dipped in reagent alcohol. The expanded spear can be allowed to dry and stiffen, then dipped in reagent alcohol. Dipping the expanded spear in alcohol can speed up the drying time.

  1. Premoisten the spear with clean water and dry if desired to achieve the desired shape and stiffness. 
  2. Dip the spear in reagent alcohol. 
  3. Gently drag the tip of the spear along the side of the knife, parallel to the edge. 
  4. Repeating on the other side of the blade and allowing to air dry.

Alternatively view the knife edge under a dissecting microscope and press the spear tip against the edge of the knife as though to split the tip. DO NOT USE DRY. Dip an expanded and dried spear into reagent alcohol and shake or blot on filter paper to remove excess.

Using little force, wipe the spear tip parallel to the cutting edge, never obliquely or at a right angle. Move across the entire length of the knife edge, then use a fresh part of the spear and repeat in the opposite direction.

ProSciTech's black ceramic zirconia scalpels are sometimes called "black diamond" scalpels because they are hard and durable, but unlike diamond, these scalpels have a modicum of flexibility which extends their life on occasions. All blades are made to most exacting standards; our photos are not retouched and demonstrate these knives' perfection. At the same time we are able to supply them at one‐third the price of similar scalpels. We don't offer a re‐sharpening service since, without even considering shipping and handling, our new scalpels are cheaper than resharpened scalpels from other suppliers. Oz and NZ customers may use our shopping cart or place an order by email or phone. Overseas customers please email enquiries ‐ we will then advise of shipping charges and produce an invoice, which can be paid via our secure link to the bank.

All handles are made of titanium and the blades are retractable.

Keep the open end free of obstructions when you push out the blade!

Telling sapphire and ceramic zirconia blades apart without a label is easy: the ceramic zirconia is black and comes with a blue titanium handle; sapphire is glass‐clear and comes with a silver‐coloured titanium handle.

Angled and large knives are in a larger diameter sheath.

All lancets are double edged, meaning the the underside and the upper side of the blade are sharpened to the edge and the profile is arrow shaped.

  • Single edge blade = the upper side is sharpened to the edge, the underside is flat.
  • Double edge blade = the underside and the upper side are sharpened, arrow shaped profile.
  • Measurements given in the name of the knives are the width of the blade and the angle at which the tip is cut. 
  • The thickness of the blade is given in the text.
  • Angled and straight refers to the mounting of the blade.

Scope of Application: Ophthalmic, microsurgical, neurological, plastic surgery, urological, ENT surgical, fine dissections and microsurgery in the biomedical sciences.

Physical & Chemical Characteristics of Sapphire Surgical Knives

  • The sapphire knife provides a superb cut, far exceeding that of a finely honed steel knife. An incision made by a sapphire knife results in significantly less damage than from a conventional steel knife, and no metal particles are left behind in the tissue, so wounds heal faster with less scarring.
  • High stability of physical and chemical properties, good biocompatibility, little effect on neural excitability, small astigmatism, neat incision, wounds healing faster with less scarring, non‐infiltration by acid and blood, corrosion resistance, effortless sterilisation.

Physical & Chemical Characteristics of Nano‐Crystalloid Ceramic Zirconia Surgical Knives

  • High hardness, density, sharpness and toughness
  • Black blade, no reflection ensures good visualisation
  • Good biocompatibility
  • Non‐infiltration by acid and blood, corrosion resistance, effortless sterilisation.
  • No metal particles left in the tissue

SpecificationsDiamondCeramic ZirconiaSapphireStainless Steel
Mohs hardness108.596.5
Viscosity (Mpa/M)610‐123‐4 
Curvature 1200‐1600300‐500 
Frictional coefficient (Kr)0.350.10.44 

Note: The dimensions in the diagrams are given in mm.

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