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100 micron spheres

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I am trying to develop sustained release pharmaceutical formulations (eg injections that would last a month).

If there was a way to print 100 micron spheres of a drug/polymer mixture that would be great - no other good way of getting regular spheres of that diameter with spray drying etc.

I am a complete newbie to 3-D printing but it seems like it could be done. We can produce a 1 mm to 2 mm rope made up of the drug & polymer for the feed.

Does anybody have any experience doing something like this?

Thanks

Tom

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Hi Tom,

Thank you for your post and welcome to the forums!

So.. do you want to print a sphere with a resolution of 100 microns, or are you asking to print a sphere of the size of 100 micron? I will say.. that latter will be a challenge!

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No, you can't print spheres that are 100micron in diameter, which is what it sounds like you want to do since you're talking about injections. Not even an SLA printer will be able to do that.

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The diameter of the (default) nozzle is 0.40mm, there are special nozzles available that go all the way down to 0.1mm, or 100micron. So you can get a nozzle that is the full diameter or the detail you're trying to print at best. But they are very very difficult to use in practice. So you're basically screwed right off the bat.

As for the resolution in the z-axis. You can technically go down to 0.02mm but you will not be able to neatly stack something that tiny on top of each other. The printer simply can't squeeze out such a tiny bead of plastic with that kind of precision. It's like using a tube of tooth paste and then try to build a bead that is 2mm in diameter, it's just going to be a mess.

Going over to SLA you are limited by the spot size of the laser and the slight bit of refraction you get in the liquid. For example, the spot size of the laser in a Form2 printer is 140micron. So again, you're SOL straight out of the box. The minimum diameter of a standing wire is 0.3mm according to the design recommendations from Formlabs:

http://formlabs.com/support/software/design-specs/

And of course, I doubt you'd be able to use SLA in the first place since you'd need to suspend your drug in some form of UV curing resin which wouldn't break down in the body once you inject it.

So, in short, 3d printing is not the right method to use for this type of production.

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If it might be printed in a plate of let's say 1cm x 1cm, and used as a sticker on the skin (like morfine stickers), that would be easier.

But you also need to keep in mind that the stuff needs to be heated to about 210°C (for PLA plastic, biodegradable and food safe, and sometimes also used in medical implants because of that). So the medication should not degrade at that temperature.

However, personally, I wouldn't want to have any particles injected. Never. If they accidentally get into the blood stream, they will block the blood transport to the heart, brains, eyes, organs and whatever else. So, that would make people braindead, blind and cause heart failure. Similar to the side-effect that kids experience when powdering and injecting their Ritalin doses, to experience the cocain-rush (that's why Ritalin is called "kiddy coke").

Any injection system based on particles is inherently unsafe and will cause severe problems in a number of cases.

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Thanks.

As a thought experiment -what would happen if the nozzle squirted (sorry about the amateur terminology) pico to nano ml pulses of polymer into a cold liquid - maybe water. What do you think would happen?

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The plastics we use (PLA, Nylon, ABS) are non-newtonian in that they stick to themselves. Like, hmm, honey? More sticky. Like mucus or snot. So it's hard to get droplets. When water comes out of a faucet at very slow speeds it breaks up into droplets. Not so easy with plastics which stick to themselves much more. You'd need to mix it with pressurized air or something and spray it straight up and have it fall back down maybe. Something like that.

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So, standard inkjects can fire off stacatto droplets because the inks they use are Newtonian?

In current 3D printer nozzles is the output a stream due to the stickiness?

Are there any nozzle configurations that can deliver digital pulses to break a stream into droplets?

Can pressurized air be added to the nozzle input?

Thanks for you patience with what may be dumb questions.

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Inkjet and 3d printers (FDM/FFF in this case) are completely different technologies. You're comparing ejecting tiny droplets of water like ink by heating it up so that it "explodes" out of a tiny pre-filled chamber, to pushing out a hot and highly viscous fluid through a nozzle using pressure.

Now, there are 3d printers that use powder and an inkjet like nozzle to spray a binder onto said powder, but then we're talking machines that are orders of magnitude more expensive than an Ultimaker.

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Inkjet and 3d printers (FDM/FFF in this case) are completely different technologies. You're comparing ejecting tiny droplets of water like ink by heating it up so that it "explodes" out of a tiny pre-filled chamber, to pushing out a hot and highly viscous fluid through a nozzle using pressure.

Now, there are 3d printers that use powder and an inkjet like nozzle to spray a binder onto said powder, but then we're talking machines that are orders of magnitude more expensive than an Ultimaker.

 

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Inkjet and 3d printers (FDM/FFF in this case) are completely different technologies. You're comparing ejecting tiny droplets of water like ink by heating it up so that it "explodes" out of a tiny pre-filled chamber, to pushing out a hot and highly viscous fluid through a nozzle using pressure.

Now, there are 3d printers that use powder and an inkjet like nozzle to spray a binder onto said powder, but then we're talking machines that are orders of magnitude more expensive than an Ultimaker.

 

Thanks. I will see what I can find out about these types of systems,

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