HDPE Casing?

The big challenge with HDPE coating implants seems to be deposition and securing it in realistic quantities; has anyone considered 3d printing? What about printing an HDPE sheath around a magnet? The bulk would be considerable but the bioproofing couldn't be beat.


  • edited May 2014
    Hm, from a quick google, it seems that the average 3D printer, can print a layer of
    0.1 millimeters, so it wouldn't make it too much thicker. Although, how would you fully encase the magnet in the coating?

    (From what I understand you can't 3D print around an object, I could be wrong though.)

    "Printer resolution describes layer thickness and X-Y resolution in dpi (dots per inch), or micrometres. Typical layer thickness is around 100 µm (250 DPI), although some machines such as the Objet Connex series and 3D Systems' ProJet series can print layers as thin as 16 µm (1,600 DPI).[16]
    X-Y resolution is comparable to that of laser printers. The particles
    (3D dots) are around 50 to 100 µm (510 to 250 DPI) in diameter."
  • the bioproofing would actually not be that great from printing. on a micro level, the surface would be extremely irregular. this would cause a lot of fouling.

    deposition of PE is just as difficult or easy as any other deposition.  Anything that is done properly, at this particular point, is not something you don in your garage. Which isn't to say that you can't get it done. I'm personally not keen on the PE polymers, but if it's done right, it would be better than what people use now.

  • Glims, out of curiosity, do you have a magnet? If so what type of coating?
  • Printing around the magnet could be as simple as letting the printer get halfway done with a hollow shell and drop the magnet in. It wouldn't be a tight casing but it would be something. The surface would be super rough but a good scrub and soak in quat for a few hours and it'd be sterile. Skin growing on and around it, though... I'd imagine getting it out would be painful at best and highly damaging at worst.
  • I do not have a magnet as I am not currently comfortable with the coating methods available. I work in a chem eng lab and we specifically been working on implantable materials for a few years. I have awkwardly high standards....

    Cassox and I have been working on a new method and I have been testing the coatings in my lab.. When that comes out, I will implant.
  • I've just implanted a paralene coated one a two days ago, and depending when you guys release your new ones, I might re-implant with one of those. From what I understand at least, after a couple years it's advisable to take out the paralene coated magnets, due to possible breaking down of the coating?
  • AFAIK parylene itself doesn't degrade on a <5 year timescale, but physical coating segregation from every day impacts can cause cracks or sloughing off. I defer to films though; IANAChemist.
  • s/films/glims
  • Nah, you pretty much got it right. The parylene itself isn't breaking down per se, however, as it is mechanically bound to the surface (no xlinking, no ionic binding) it will eventually flake and peel off from impact. 

    The samples that we have tested show that this can happen even from just casual handling. The coating is very thin, and highly irregular. Thin is good, irregular not so much.
  • Realistically, what would happen to an exposed neodymium magnet subdermally? If my parylene coat breaks down, will I know before I start having deleterious health issues? From what I read, the oxidation will be visible (indicating it will be super brittle) before I have big issues, at which time I would need to quickly remove and flush. What do you think/is your experience.
  • Click here to see photos of Shannon Larratt's ruptured first-gen magnet being removed: http://www.zentastic.com/blog/2006/11/20/magnetic-implant-removal-part-ii/
  • Yeah, I've seen the pictures - finger surgery is crappy, but frankly I'd be more concerned about heavy metal poisoning, which he doesn't discuss... I don't know if that concern is warranted or not, though.
Sign In or Register to comment.