Who wants smaller magnetic implants?

edited December 2011 in Magnets
Using magnets smaller than those 3mm diameter stir elements might be a good idea, for several reasons. A smaller magnet will fit more easily in the finger, require a smaller incision to insert, and be less likely to damage the finger if it gets crushed or hit. Because it produces a weaker magnetic field, it would 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. Hopefully these two effects would balance out, making the smaller magnet about as sensitive as the larger one (I could try to do calculations to verify that, if people want).

Unfortunately, I haven't found any smaller, off-the-shelf magnets that are coated in parylene - we'd have to get a custom order, and that will be more expensive. I talked to a company about getting magnets with a 2mm diameter and .7mm thickness. 

Here's some comparisons with the 3mm diameter, .7mm thickness stir elements: the smaller magnet's field is 52% as strong as the original's, but it only weighs 44% as much. It's got a better magnetic field strength to mass ratio than the original. 

We could get 50 of these magnets for about $13 each. This is a significant amount of money, but if enough people are interested maybe we can work something out. So, who's interested in smaller magnets? What are your thoughts? 

(We could also look into getting 1mm diameter magnets, which have an even better field strength to mass ratio. I have a spreadsheet comparing different magnet sizes, let me know if you want a copy.)



  • Please, send me a copy of the spreadsheet. 
  • Pass it on to me too, please? Also, how much mass would coating add?
  • The parylene coatings on the magnets I've asked about are 20 microns thick. I guess we could find out the density of parylene and calculate how much mass it would add based on the surface area of the magnet, but for now I'm willing to ignore that added mass.

    As an update: I like the idea of tiny, bioproofed magnets that could be injected using a hypodermic needle. Something <0.5mm in each dimension might work nicely. Unfortunately it looks like that would also have to be a custom order, so we'd need to have an organized group-buy or something.
  • First off, 
    Nice to meet you all.

    Second off,
    This link apparently sells magnets as small as .25mm, pre-biocoated.  I'm a martial artist and string bassist/bass guitarist, so I've been loath to get multi-millimeter implants in my fingertips for a while now, but as was written, this could make installation and healing time to full implementation much easier/faster, in the range of weeks instead of months.  We'd have to e-mail them for a quote, though.
  • Welcome!

    I've been in touch with that company - they don't have any suitable magnets in stock, but we could place a custom order. I'd rather not contact them again (I think I used up their patience by asking stupid questions), but maybe if @PsynFyr or someone else wants to email them and ask for a quote, we could get a sense of how much this might cost.

    I think I'll email the other company that gave me the quote for the 2mm diameter magnets, and ask for another quote for 0.5mm diameter, 0.5mm thick magnets.

  • As another guitarist I'm also highly interested in this. If others are still intrested I would like to take part in the buy in.  
  • Depending on the price I would think about another implant as well
  • edited January 2012
    They (BJA Magnetics) are currently working on a quote for me.
    150 or more 1mm (d) X .5mm (h) parylene-coated n52 magnets, axially (diametrically) magnetized.  Their custom magnet facility has apparently been on holiday, but they said that they should respond sometime soon.  

    I figured axial magnetization would allow the magnet to sit on its side, causing less interference with the finger-pads while having a pole facing parallel to the palm when the fingers were outstretched.  

    I went ahead with 150 of them mostly so that I would be seriously considered, and because if it works out well I plan to have a several in me.  If anyone wants to jump in on the order, that would be awesome.  Officially, they are being purchased through my ministry.
  • the given dimensions sounds a lot easier to implant with a needle. if the price is reasonable, i'd be in for a bunch.
  • I'd be in for a dozen. Post a group buy.
  • That's great! Thanks for contacting them. 

    I was thinking that one potential problem with tiny magnets is that if they're small enough, one could be accidentally injected into the bloodstream and that would be bad. However, I did a bit of research and I THINK the blood vessels in the fingertips are all at least slightly narrower than 1mm, so these 1mm magnets should be safe. We may want to verify this.

    About the group buy - it would be awesome if we could use a service like kickstarter, so that people could pledge money and it would be held in escrow until the magnets were purchased. I don't think this particular project would be allowed on kickstarter, but does anyone know of a similar service that would allow group buys and not just creative projects?

  • all you need is a trusted person. in simplest case, the person buying the magnets. for the last group buy we know that magnets aren't terribly expensive. so the loss for any party would be small , if any.
    depending on the price i would be in for up to 20 magnets, if they are cheap, even more.
  • I'd be interested in 10.
  • Depending on the price I'd take 10 to 20 as well.
  • Can I get a price? 
  • Does anyone know the gauge of rfid implant kits like this one?  

    I can't help but think that these could make for far, far easier implantation.
  • edited January 2012
    those have about 2mm inner. and 2.5mm outer diameter. so they probably are gauge12. from personal experience, they are big, a lot bigger than the magnets in question here. you probably want to go with 15 or 16 (for a 1mm diameter magnet), if the magnets fit inside.  and gauge 20 for a 0.5mm diameter.

    implantation with those applicators is very fast. maybe not on the fingertips. but my rfid in the back of my hand took bout one second, might have been even less.

    btw. any chance to get cylindrical instead of disk-shapes? like 0.75mm thick and 2mm long? that would work a lot better with hypodermic needles as the magnet wont flip inside the needle.
  • Darn.  I had hoped they were no bigger than 18.
    Yeah, I think 15 would be perfect for this.  It would leave a little bit of leeway for tolerances.
    I wonder if I could rig up something similar to the rfid implanters with the smaller needles.  Probably so.  

    The magnets I've been looking at would be custom-made anyway, so I guess we could ask for another quote, but .75mm diameter is a little under the average diameter for ulnar arterioles in the middle finger, if I recall.  That could potentially be a problem.  

    I just figured I'd take one of my electromagnets and hold my fingers up to it soon after injection in order to orient it how I wanted.  
  • Umm... Hi

    Have been lurking around for a little while now but little time at present for personal projects.

    However this is an excellent looking opportunity to pick up resources for later in the summer when I will have more time.

    So yeah, put me in for the group buy if you may - I'm not sure how you all work these kinds of things here but hopefully we can work something out.  I guess 10 is a relatively reasonable figure given that I'm sure to screw it up and/or want spares for monkeying around with.

    Haven't really had much time to research details on sizes etc so I'll leave those decisions with the many more wiser heads available.
  • Also depending on the price I'm up for about 15.
  • Hi, I'm another lurker and I'd also be interested in taking part in the group buy. Something like 5-10, depending on the price as well.
  • I'd be up for 15-20.

    Nice to meet you all by the way.
    This place seems pretty amazing.
  • Bad news, guys.

    I've received a quote from BJA Magnetics, and they want $6.16 per magnet, which is about three times what I expected and five times what I was hoping for.  I could forward the quote to any person wanting it, but I can't front that kind of money right now.  

    Anyone know any other companies to contact?  
  • hm.. for 150 magnets minimum order i guess?
  • There are a few ways we can make this work.

    1) Someone who is willing to front the money could order the magnets, and then resell as many of them as possible (without a guarantee they'll all be bought).

    2) A small group of people could split the cost of the magnets, and then try to resell them to others. This would require good organization and trust.

    3) We can use a kickstarter-like crowdfunding service that will allow people to pledge money for a certain number of magnets. If enough money is eventually pledged, the order can be placed. fundageek.com might be appropriate. A lot of other crowdfunding sites accept only creative projects, so unless we can find some way to make this sound like a legitimate, not-dangerous art project, there aren't too many options. (maybe the "reward" for pledging money could be some kind of craft item that uses the magnets?)
    This option is the least risky for everyone involved, as long as the person making the purchase can be trusted.

  • I think everyone here would prefer option number three. It makes sure I won't get ripped off and that the people who are kind enough to supply the magnets won't run into the same problems as last time. 

    Does anybody have websites we could use to start fronting money? There could also be a combination of one and three where we could supply the bulk of the money and any left over we could help try and sell. If we all work as a group this is still doable. 
  • once again. what's the total ammount of money we are talking about here? 6 bucks on 150 magnets would be quite a alot.
  • That's ~80 bucks each, if all eleven people in the thread want to do it. Get more people in on it and that's really a pretty good price. 
  • Though 6$ per magnet is way more than I expected (extrapolating from last time) so I wouldn't do it, I guess. Sorry, but for a little comparing experiment that is to much...
  • Since I don't have any implants yet, I'd still be very interested. 
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