Group buy: high grade PTFE-coated cylindrical magnets

edited February 2015 in Everything else
Hi all!  I'm new here.  A friend of mine asked me to host a group buy for teflon coated Alnico 5 magnets from BOLA, as they don't sell to individuals (I have a registered company).

Several people on the IRC have already said they want some, so I was wondering if anyone else here was interested.  The price is about 1.53 euro each for 5x2 magnets (length x dia, in mm), or 1.23 euros per 7x2 magnet, excluding the shipping to you (which will probably be less than 3 euros per person).  The magnets are FDA conform and have excellent universal chemical resistance.  They are sold as stirring bars, which means they are made to endure a lot of mechanical stress.

We picked these because they would be easy to implant by injecting them using a hypodermic needle, removing the need for scalpels or suturing.  The cylindrical shape should also significantly reduce the chance of the magnet flipping around inside the finger.

There are also other sizes available.  8x2 costs 1.44, 6x3 costs 1.20.  There's a minimum order amount of 10 for sizes other than 5x2, unless others are interested in the same size too.

Let me know if anyone is interested in a bunch of these.  I accept wire transfer, PayPal and Bitcoin.


  • When will you place the order? I'd like to buy some of 5x2, 5 maybe :D
  • What's the needle size? Are you also willing to send to the United States, if so how do you want to handle the Dollar to Euro conversion? I'm guessing you are the friend ThomasEgi was referring to in the other thread, so welcome to the forum.
  • rdbrdb
    edited April 2012
    I'll place the order sometime next week, when I have the details and confirmed amounts of everyone who's interested.

    I can send the magnets to anywhere in the world.  I'm fine with a PayPal transfer, which automatically does the conversion.  Bank transfer works for me too, or Bitcoin.
    I can calculate the amount of dollars or bitcoins for you if you wish to pay using dollars/bitcoins.

    As for the needle size; the magnets are 2 mm in diameter, so needle size #12 should probably work.  I have never tried it, so I can't recommend a particular method though.  Alternatively, you might be able to find an RFID tag applicator.

    There are several people interested in the 7x2 magnets too, so the minimum order amount of 10 does not apply for that size anymore.
  • As discussed in IRC, consider me in for 12 of the 5x2's.
  • I'd like three 5x2 and three 7x2 if possible, I'd like to do some experimenting with the different types. PM me the payment details when you're ready. 
  • I'd be interested in picking up five of the 5x2's as well.  Thanks!
  • How do these compare to the n50s in strength?  
  • That's hard to say.  The intensity of the magnetic field depends on the size of the magnetic core.  Alnico 5 does produce a weaker field than neodymium, but it's hard to compare as there are many factors involved.

    Keep in mind that there's no way to predict how strong the magnetic vibrations will be once implemented.  There are too many factors involved - which way the magnet is oriented, the exact nerve density around the magnet, how the procedure is performed, how well the tissue around it heals; etc.
    Since (as far as I know) nobody has used these magnets before, there's really no way to tell how well they will work.
  • Can you stick me down for 5 5x2's, please?
  • edited May 2012
    @cerasi made a strong argument for smaller magnets: as small as 1mm x .5mm. There are exponential gains in field strength in relation to size the smaller the magnets.

    I would caution waiting to commit to a size until we're sure how small these can be made viably.
  • I agree that these are NOT the best magnets to use, because they are bulky and weak.

    Here's the argument for smaller magnets (such as 1mm diameter x 0.5 mm radius): 
    "A smaller magnet will fit more easily in the finger, and be less likely to damage the finger if it gets crushed or hit. It can be injected with a small hypodermic needle, which is simpler and less traumatic than making an incision. Because it produces a weaker magnetic field, it will be less likely to interfere with electronic devices - but because it has less mass than a larger magnet, it should move more in response to outside fields."

    The key here is the ratio between the magnet's strength and its mass. A high field strength to mass ratio should mean better sensitivity. There are other factors that affect sensitivity too, but this is a good place to start. 

    I made a graph that shows how the strength/mass ratio changes with the size and shape of the magnet:

    Small magnets have a much higher strength/mass ratio, so small magnets should be more sensitive! 

    The magnets people are talking about buying here have a pretty terrible strength/mass ratio. They're made of alnico, which is weaker than neodymium. They're big, and they're coated in teflon which adds extra weight and bulk. We can do better than that.

    Back in the "Who wants smaller magnetic implants?" thread, we were talking about placing a custom order with BJA Magnetics for some very small and powerful magnets (1mm diameter x 0.5 mm length, N50-grade neodymium, parylene-coated). We can get 150 of them for about $6 each.  (We could get even smaller magnets, but if they're too tiny, I'd start to worry about accidentally injecting one into a blood vessel.) I suggest that we plan a group-buy for these magnets (or similarly small ones), instead of the big teflon-coated ones above.

    PS.  Here's a spreadsheet with the data that was used to make the graph, if you're interested.

    Small magnets are more sensitive than big magnets: . These magnets are big and weak, so you should buy smaller, neodymium ones instead.

  • edited May 2012
    @cerasi BJA Magnetics had a few samples I requested in a somewhat larger size than our target but refused to deal with me after extensive talks. Why not go to the source? China. There are a number of suppliers on Alibaba.

    And it could help reading this handy guide to purchasing things from China.
  • edited May 2012
    about all that sensitivity discussion (which is not part of the group buy anyway).
    as rdb pointed out. it is very hard to predict the final preceived sensivity.

    the field strength itself is by far the least concern. it falls off extremly rapid if you move away from the magnets surface. if anything about fields would be of importance, then it is the strength and size of the field you want to feel.
    this will also determin the overall magnetic flux that'll be flowing. and that in turn will give you the forces that occur at the magnet. and those , depending on the magnet's shape and size, will press/vibrate/rotate against the surrounding tissue. which would be the end of the mechanical sensory chain.

    piking a stronger magnet will do very little, compared to moving your magnet a bit closer into the field.
    having a bigger magnet will give you a bigger force, but that distributes over a bigger area so there is less pressure to be sensed. while having a long thin magnet will give you a higher angular force ,but at thesame time the shape is a longer lever so the tissue can counteract with less force to be sensed.
    one thing about smaller magnets is their smaller mass, which means less inertia, which does allow them to move faster given weak fields.

    long story short: impossible to squeeze into a spreadsheet with just a few squareroots. if you want to calculate, you wont get around a lot of really nasty math. not counting mathematical models that could give you a number on preceived magnet motion.

    to sum up a few points from above.
    compared to most of the magnetic disks people implanted in the past, these magnets are quite a bit smaller already.
    compared to N50, these magnets arent quite as strong, but they are still pretty strong and on top of it, alcino is very very long-term stable when it comes to its magnetic properties.
    compared to some magnets from some factory somewhere in china with unknown quality standards, these magnets are lab-grade FDA approved quality.
    compared to the smaller parylencoated neodymmagnets, these have a pretty thick coating which makes them more robust(biologically and mechanically). (besides PTFE wont connect to the tissue so it'll be easier in case you want them removed)
    last but not least they cost only a fraction of the smaller neodym-parylene ones (and can be ordered in lower quantities).

    there is no garuentee for excellent performance. so the biggest risk is that they wont work, but chances of breaking, poisoning etc are very low with these.
    so they are well worth to be tried out. we are still experimenting after all, otherwise we wouldn't be searching for the "perfect" magnet to implant.
  • rdbrdb
    edited May 2012
    I also respectfully disagree with the assessment that "smaller is better and therefore we need to all buy these even tinier ones".

    First of all, the magnets that we're buying are already quite small compared to the ones already used in magnetic implants.  They can be implanted using a hypodermic needle, so no incision is required.

    I also think that there is a limit to how sensitive we'll want the magnets to be.  At one point, I think most of the experiences with it will feel painful rather than like a light buzzing.  Since parylene bonds to the tissue around it, having one flip over inside your finger when you hold a fridge magnet near it would certainly be quite painful.

    In the end, there are simply too many factors involved with the effectivity of these magnets (some of which Thomas laid out above).  The only way to find out is for somebody to actually try them out.  This effort is supposed to be an experiment - if it works, we know what works, if it doesn't, we know what doesn't.  Given the fact that these magnets are relatively cheap and available in low quantities, I don't see a reason not to try.  They should be relatively easy to remove due to the fact that they are coated in PTFE.

    I agree that there are certainly merits to smaller magnets, but both should be experimented with to see which works better in the end.

    Anyway, this is not really the place to hold a discussion about the type of magnet; this discussion is about the group buy.  I'm going to be sending out e-mails and messages to the people who are interested for a final confirmation and the payment details.
  • Well, I would be interested in eight of the 5x2s and eight of the 7x2s, though I'll try and compare them to the neodymiums once I get my hands on some (or some in my hands).  
  • edited May 2012
    I did not intend to turn this into a broader discussion, only to open the discussion to the consideration of smaller sizes. That said, I'm in for 5.
  • I'd be in for 10, 100% keen.
  • When is this expected to go ahead?
  • rdbrdb
    edited May 2012
    As soon as I have confirmations from most of the people who were interested.  iPaaaLmad, Unqualified and Rasputin have not replied to my private messages yet.  PsynFyr and SovereignBleak have confirmed, but not yet paid.
  • Ok, I replied to you.
  • Replied :D
  • New here. I'd be down for 10 as long as having them shipped to Las Vegas is cool.
  • All right, I'm about to close up the group buy.  I'll be placing the order with the manufacturer next week.

    Could everyone who indicated their interest be sure to check their messages and everyone who hasn't yet paid be sure that the payment is made this weekend?  Thanks!
  • rdbrdb
    edited May 2012
    Update: I just got a call from their Dutch distributor.  It will take max one and a half weeks for them to receive the magnets from the manufacturer.  When I receive them, I will put up a picture, and I will start sending them out to everyone who has paid for their magnets.

    I still don't have all of the payments in.  Regardless, I have covered the expenses for the people who haven't paid yet, but I would appreciate if those people could still do so.
  • Just confirming that you received my payment through Paypal.
  • Yes, thank you.  I have received payments from everyone but PsynFyr and Bish.
  • It is true that there are a number of other factors involved in magnet sensitivity. I look forward to discussing these factors more and improving our theoretical model (at another time and thread), and seeing how different magnets perform. Best of luck with the group buy, and the procedures!
  • I'd like to thank you Cerasi, within a public forum, for taking the efforts to improve our current limited understanding of sensitivity with the mathematical data you provided. Here's to you and the forum, may the best model improve us all!

    I also look forward to discussing the magnet's performance. I plan on putting both in separate hands as a comparison. Good luck with implanting these magnets everyone, be sure to sterilize. 
  • rdbrdb
    edited June 2012
    The 5x2 magnets just came in.  The 7x2 ones are still on backorder.
    Here are the pictures as promised (sorry for the poor picture quality, I don't have access to a good camera at the moment):

  • When you planning on implanting one? We'll want details and updates on sensitivity.
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