Certifying Magnets - A process
  • ZerbulaZerbula December 2016
    I propose that a regular, repeatable method to test and validate a magnet's integrity be set up. 

    A standard, of sorts, to simply help us identify good from bad. I know this idea has popped up and been kicked around a lot, But we have yet to actually develop any regular system to validate magnets, unless I have missed something. Easily possible. There are snatches here and there of x or y process to test, but can we bring it all together and make it concise? ^^'


    Of course, things such as saline solution exposure and visible inspection should be in this category, but what other tests should be executed? Destructive and non-destructive? 

    Ideas, thoughts? :D

  • tekniklrtekniklr December 2016
    I know everyone brings up salt water soaks all the time, but there has to be a better thing to try soaking in... vinegar? milk? I don't know. The body is way more corrosive than salt water, so it seems we should test magnetic coatings with something more corrosive, too.
  • njmbb8njmbb8 December 2016
    how about lye? i know that i've read that bleach can damage TiN
  • MeanderpaulMeanderpaul December 2016
    I think there's a couple reasons why it's saltwater. One being if there is any defect in the coating then it's a failure and we aren't trying to make a coating fail just trying to find the defects.
  • ZerbulaZerbula December 2016
    Agreed. The solution, or at least the most commonly used one, should be compatible with coatings, and Incompatible with the coated material. Heating salt water may create more reactivity as well, correct? What about agitation?

    What kind of salt water is going to be the most aggressive? Research needs to be done... :3


    @njmbb8 Not sure, but that's an idea! Will look into it. :D


    What other methods can we use to test magnets, Besides just salt water?
  • JoshJosh December 2016
    I'm just wondering what annihilating the coating would be useful for? You can't implant that magnet now, and it seems like a waste of $60 from a consumer standpoint. Mild salt water is used because consumers just want a readily accessible test with results that are easy to read to see if any part of the magnet is exposed. For all I know, the body doesn't even break down TiN (but please correct me if I'm wrong).

    Basically, I just want to know why a more aggressive test is needed :)
  • tekniklrtekniklr December 2016
    The point wasn't to annihilate the coating, but to use a harsher test that better simulates what's going on in the body. If a coating is stable for, like, weeks in say, vinegar, then maybe it would be stable indefinitely in the body.
  • JoshJosh December 2016
    That makes sense. Do we know the kind of stress that the human body places on the coating? It was my understanding that bioinert coatings should be left alone by the body.
  • tekniklrtekniklr December 2016
    Well, so there are two separate things worth testing- coating integrity (if it is doomed to fail because the magnet is exposed already), and coating stability/durability (whether an initially good coating will eventually be broken down by the body). The body puts a lot of stress on coatings, which is why this is such a hard problem. Also, there is still a lot of debate over which coatings are bioproof enough without adding too much thickness. See: every topic where people mention parylene. ;)
  • ZerbulaZerbula December 2016
    Indeed. :D

    The reason I want to push for a more strenuous tests is to validate their integrity. Of course, not to the point of Destruction, nor as mild as a saline solution.

    Saline Solutions are valuable test, though. But is there better ones? Even as simple as using different salts to get better results... :0
  • MeanderpaulMeanderpaul December 2016
    So we are very quickly exiting my knowledge level on this subject but I believe the heated salt speeds up the reaction (I remember reading that some where). I can't remember from bio but was the body acidic or a base? Perhaps a solution that is acidic or base, based on that answer?
  • JoshJosh December 2016
    What kinds of stress does the body put on the coating? Acidic, temperature... ?

    I'm assuming we're trying to mimic the body's response to the magnet, right?
  • MeanderpaulMeanderpaul December 2016
    Coreect
  • mmuyskensmmuyskens December 2016
    why don't we just source some cadavers? lol
  • ZerbulaZerbula December 2016
    This brings up an idea...

    Let's reanimate a single finger and use that to in vivo test magnets! :D



    How hard can it be... A little pump to pump blood... Some tape to stop the blood from coming out... You're onto something, @mmuyskens! :O
  • actiiactii December 2016
    Ask Dr. Frankenstein... Maybe grow a finger on a mouse while we are being fanciful
  • MeanderpaulMeanderpaul December 2016
    Dead critters...
  • MeanderpaulMeanderpaul December 2016
    ANIMAL TRIALS!!
  • mmuyskensmmuyskens December 2016
    I have a few bodies in the back of my work van I can sell you for cheap...
  • misslittymisslitty December 2016
    Cadavers wouldn't be producing any of the factors responsible for foreign body response so you'd have to find a way to account for that.
  • ZerbulaZerbula December 2016
    @misslitty Shhh... >3< 
  • MeanderpaulMeanderpaul December 2016
    Just tossing it out there again....ANIMAL TRIALS
  • Rocco8620Rocco8620 December 2016
    @Zerbula hahahahahaha

    @Meanderpaul are you serious?
  • katzevonstichkatzevonstich December 2016
    Alternately, we could just shove them in all sorts of random environments to see what would happen. Salt water, fish tank, dead fish, etc. Maybe the compost bucket isn't quite a good mimic of the human body, but surely all of it put together would be a decent analogue.

    I say this mostly tongue in cheek as I'm still a bit woozy from Friday's surgery.
  • MeanderpaulMeanderpaul December 2016
    No, not serious I wouldn't want it to possibly hurt an animal. that would be a better long term test then short term.

    I do like the idea of a fish however ( not kidding) fish a very sensitive to changes and you'd see a negative effect VERY fast.
  • mmuyskensmmuyskens December 2016
    I'll vote fish as well - just because they make a tasty treat if they do die.

    mhmmm fish fillet....
  • IvoTheSquireIvoTheSquire December 2016
    Animal trials is always the gold standard.

    It's not just how the coating responds to the acidity (blood is a bit alkaline around pH 7.4 from memory) but also how the coating would respond to the body's response (inflammation, attempts in phagocytosis, all that gist). This is a dynamic process which cannot be simulated statically by a chemical (it will be like trying to find a material that can withstand going from 10,000 degrees to 0 degrees cycles by putting them in 5,000 degree heat). From memory cell cultures are used for in vitro biocompatibility testing (pre-clinical trials), but animal trials (phase I clinical trials) is always the next step before going into a human body.
  • ZerbulaZerbula December 2016
    Would... Culturing a bacteria in a petri dish and having the magnet within the matrix be anything useful in regards to a test? :O


    Also, I think it would be best if there was a distinction made, perhaps two different types of certifying should be in place: 

    - One for the absolute best of the best 'We will fuck your shit up' Judge-o-tron 69,000... 

    - And a test someone with minimal scientific background could preform, with little equipment and training.
  • IvoTheSquireIvoTheSquire December 2016
    I would doubt that bacteria is representative to the human body as they're prokaryotes as opposed to eukaryotes which is what we are.

    I can't remember on top of my head what sort of cell culture they use for biocompatibility testing. We might be able to find something by digging up some papers on biocompatible materials.
  • njmbb8njmbb8 December 2016
    ISO 10993-1 recommends mammalian cell culture media if i've read it right
  • glimsglims December 2016
    Mammalian cell cultures are the closest you're going to get without just implanting. The step down from that is probably complete plasma in a flow chamber.

    Bacteria are good for adhesion testing and fouling testing. They're a bit more aggressive so you have a nice buffer with your results.
  • IvoTheSquireIvoTheSquire December 2016
    Aren't there different types of mammalian cell cultures as well? I would imagine we would need specific ones (no point in using the HeLa cell line now is there?).
  • glimsglims December 2016
    Yes, there are many types of mammalian cell types. I figured using the 3t3 line and the HepaRG line was sufficient. It really covers your bases.
    HeLa per se is not your best bet, but it is the most common. One way or the other tho, you are using immortalized cell lines. Otherwise they just die.
    This is why labs move on to implanting in rats. Because you can't make normal cells happy (easily) in a lab setting. 
  • MeanderpaulMeanderpaul December 2016
    Cough ANIMAL TRIALS cough
  • IvoTheSquireIvoTheSquire December 2016
    Yeah, I know about the animal trials (hence my comment on it being the gold standard. Short of human trials anyway). Just thinking about the in vitro stage that is right before that that's all.

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