The scalpel: From flint to zirconium-coated steel (2018) | Hacker News Reader

The scalpel: From flint to zirconium-coated steel (2018)

facs.org

32 pointsaccrual9 comments

Anyone else found it odd that the article says "For all the improvements evident in contemporary surgical technology, electron microscopic images actually confirm that the edge of Neolithic obsidian blades exceed today’s steel scalpels in sharpness" and then cites a paper about obsidian blades from 1982?

Has there been no improvement in sharpness in 42 years? Or are Neolithic obsidian blades just that much sharper?

apparently yes. Broken glass (which obsidian is, a volcanic glass) have edges a few atoms wide beating anything manmade.

Yes but it is not very durable and the blade dulls quickly, hence all the effort on fancy steel blades.

They are fragile I've heard, and quite likely they dull quickly (don't know), but I'm not saying they're 'better' than steel; it's not a competition. Horses/courses.

From a pure sharpness perspective, you can't actually get any sharper, but it turns out there are many other physical properties (toughness, ease of sterilization, repeatability of manufactured tolerances at-scale, etc.) of a practical cutting edge where steel overwhelmingly beats amorphous ceramics.

FWIW, many surgical operations done today that require a very high-precision cut use numerically controlled lasers. Unfortunately, lasers will never work for certain procedures where cauterization would hamper healing or tissue reintegration.

There are glass fractured blades that form the same edges and diamond scalpels too, all of them show brittleness issues to lateral moves especially. The physics of steel cutting edges get very complicated in general as can be shown by an example of how human hair can damage steel here: https://www.reddit.com/r/EngineeringPorn/s/6xHn8TQEtK

I tend to geek out over the topic of cutting as it’s endlessly complex from biological matter all the way to cnc.

I thought this was pretty neat:

> Some archeological specimens are still sharp enough to incise skin.

I do kinda wish the article spent more time on modern implements too though, this is all there really was:

> Recent technological improvements include zirconium nitride, diamond, and polymer coating that enhance the cutting edge.

I went and found interesting one that looks like it's had some enhancements made. It has a color coded blade size system, and has a clear, retractable cover. The edge of the blade is also coated with zirconium nitride.

> https://www.jaisurgicals.com/diamantine-safety-scalpel.html#...

https://www.medtronic.com/covidien/en-us/products/electrosur...

Zirconium nitride, not plain zirconium.

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