Bio safe materials

Just a curiosity. What materials are longterm safe in the human body?

Off the top of my head:

Glass (certain grades)
Stainless Steel (VERY specific grades)

Assuming of course all these materials are smoothly polished so as not to give an infection a place to start.

What else is there?

I would say that this list is difficult because there are specifics attached to lots of materials, and there are also use case issues to cover. For example, PLA (that stuff you can print with) is also generally considered “biosafe”, but it also dissolves in the body. Teflon has other issues, and gold both physically abrades as well as “dissolves” in the body (bodily fluids basically etch it away slowly).

To give you an idea of all the different potential issues, check out the ISO10993 in all it’s parts… that will give you an idea just how complex “safe in the human body” can get.


Have to make sure its surgical steel, I have seen people put safety pins in as earing and never take them out and have them dissolve completely

Stainless steel - of any kind, even surgical - isn’t an inert material by any means. It’s very easy to degrade, even outside the body. People think it is because their stainless steel cutlery stays shiny. But resistance to mild atmospheric conditions is a simple requirement. Also, it contains chromium and nickel, and those metals tend to leach out of the material. Many people are allergic to chromium and nickel.

As for the other materials, I don’t know anything about their biocompatibility - apart from two: I have a bunch of titanium hardware in my knee, and my meat and it seem to have pretty much ignored each other’s presence for the past 35 years :slight_smile: As for glass, well… implants. They seem okay.

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Teflon is used in replacement joints. I’m assuming then that it takes 10+ years to do damage? Assuming of course, that friction doesn’t wear it out first.

Does PLA generally follow the same timeline?

So, is titanium better in terms of degradation?

It goes pretty fast actually… well under a year for most parts, that’s why it’s approved only for"limited" and “prolonged” devices but not permanent contact.

The issue with Teflon is monomer elements tend to slough off and basically float around the body for a long long time afterward. It also has such a high working temperature that basically anything sensitive you want to put inside of it get blasted. It’s ok for forming like solid rods and machining what you need from it out of solid teflon, but as a biohacking material it’s not all that awesome.

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I still have my leg, so I guess so :slight_smile: Although the bits I have in me are in my bones, and last I checked - or the radiologist, rather - they’ve been pretty thoroughly encased in even more bone produced by my body over the years to isolate the foreign objects. It’s called osseointegration, and it’s a pretty fabulous process: it’s the principle behind dental implants and advanced limb prostheses that attach directly to the skeleton. Check out that guy:

I sure don’t want an amputation, but I kind of dig the gadgetry aspect of it :slight_smile:

Another material that should be pretty safe is medical grade silicone - at least a lot of people keep that inside their bodys for quite a long time. Additionally, it’s lightweight and - to a certain degree - flexible, so it’s more comfort compared to titanium and other metal stuff.
Honestly, I have no idea if it is great for biohacking, simply because it makes the implants a lot thicker and might reduce the possible reading distance and all that…

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Well, many people have many things inside their body that aren’t necessarily safe, but just end up staying there without ill effects. For instance, I have a small lead pellet in my back. I don’t really know how or when it got there, but it’s clearly a bird shot, so probably during a hunt. It was discovered one day when I passed an X-ray. When I asked the doc what to do, he said to just leave it there if it doesn’t hurt, because apparently it’s been “contained” by my body or something.

I wouldn’t really call lead bio safe though. Encapsulated or not, it’s gonna leach a litle over time.

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It probably ain’t. However, I have none of the symptoms of lead poisoning. My point is, the body can be a pretty accommodating machine in the right circumstances.

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