Exciting baby-saving technology! Boring 3D printing.

By now you may or may not have heard how a 3D printed tracheal splint saved the life of an infant on the verge of having a collapse of the trachea. There are so many kinds of awesome in this story! (TIME writeup here; original paywalled writeup here.) 

The stent was custom designed and printed at the University of Michigan for the specific anatomy of the baby and served (as far as I can tell) as a sort of last ditch Hail Mary for fixing the problem. Digital designs of the trachea and splint were assembled, a biocompatible polymer was printed from those blueprints, and a life was saved.


Image from Dr. Zopf and team’s report in the New England Journal of Medicine, linked above. Not just printing splints, but tracheas too!

For the baby (and for the rest of us who may need some custom-fit medical TLC), this is an amazing use of 3D printing. It’s a perfect example of why every medical institute and hospital should have a 3D printer. But as a posterchild for the technological potential of 3D printing?  I can’t help but feel it’s kind of lame.

See, the stent was printed from a single semi-rigid material – polycaprolactone. Yawn, been there. Printing a single polymer ain’t that impressive anymore. Hell, folks have been doing this since before the marketers ever started calling it 3D printing (just one example: http://www.sciencedirect.com/science/article/pii/S0378517397001658). 

Popular internet disclaimer here: I am not a doctor. But here’s what I imagine the priorities are for a splint:

  1. Mechanical stability (“Hey splint, hold my trachea open please? Got it? Not gonna drop it on your toe in a few seconds? Great!”)
  2. Bio-compatibility (Cells aren’t exactly the sharpest cards in the deck. They may not realize that crazy thing which was just jammed in your neck is actually saving your life instead of, say, being any other number of things that are not so beneficial when jammed in a neck which require immediate removal please.)
  3. Degradability (Remember as a kid outgrowing your favorite t-shirt but trying to squeeze into it anyway, often with dramatic seam-rippage? Now imagine a stent squeezing down on your trachea like that after it grows. No thanks.)

We’ve been doing stents and splints for a long time. We’ve figured out how to hit those priorities quite well. The real exciting news here is time and customizability. The fact that the doctors have access to a 3D printer which could print a stent exactly matching the infant’s anatomy faster than they could get one traditionally made is awesome! Tech with a low barrier to entry (cost, complexity, etc.) having a significant societal impact is always a good thing.

But just printing a biodegradable plastic splint is not terribly impressive. There’s not a whole lot technologically interesting here. More often than not, the rallying cry I hear around 3D printing centers around printing any object you could conceivably want. And that’s simply not achievable now. What makes something a table or a sponge or a computer isn’t just a shape (I would be remiss not to mention cargo cults). It’s the materials used to make them. 3D printing has great control over shape. It has terrible control over materials.

Cago cult plane

“Pilot to tower: I feel like I’m flying a bundle of wood up here!”

Maybe this is just the jealous materials scientist in me talking.  “Guys, there are all these crazy wild materials and composites you could start printing!  Pretty pretty please?” Making, say, a squishy stretchable biocompatible doodad with integrated electronic components is really hard from a conventional manufacturing standpoint. It requires at least three different classes of materials needing to be combined and assembled in intricate ways with high spatial fidelity. We’ve got all of these materials, and we know they can be 3D printed. So why are we still stuck with simple rigid mechanical scaffolds and hobbyist parts? The hard science is done. All (ok, maybe most) of the details you could likely want about the print-ability are already out in the scientific literature right now. Further studies on the fundamental science are going to be few and far between. “It’s an engineering issue,” I can hear the NSF respond to your 3D printing grant proposal as they decline funding.

I’ve read a lot and interviewed with some 3D printing companies, often in job hunting mode (yes 3D printing dudes and dudettes, I’ve asked some of you for jobs). None of them seem to be thinking about materials in any meaningful way, as far as they’re willing to talk about. Which is a shame, because the platform is itching for it. “Yeah, we want to make squishy things and electronic things and biological things!” they say. But then you ask how, and they get fuzzy on the specifics. And by fuzzy, I mean THERE ARE NO MATERIAL SCIENTISTS ON YOUR TEAM WITH THE LEEWAY TO DO ANYTHING INTERESTING. There are one or two exceptions. Stratasys, for example, seems like they’ve got their heads on right for the long term. The other guys? Unless they really start thinking about composites, and multi-material printing, and moving away from ABS, there’s going to be a long slide into stagnation and exclusive appearances on Etsy jewelry sites.

Make it so, Number One!

Captain Picard would probably replicate a whole lot less Earl Grey if it came out as a cup full of plastic.


Anyway, all of the above is small potatoes: a bit of nitpicking and cynicism about the reporting around 3D printing I’ve seen. Because I absolutely do not want to overshadow the real fantastic headline here: Science – Now saving babies faster and better! If the worst 3D printing can do is save lives, I think we’re in pretty great shape.


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