this post was submitted on 19 Feb 2025
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MIT Demonstrates Fully 3D Printed, Active Electronic Components (hackaday.com)
submitted 1 day ago by cm0002 to c/3dprinting
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[–] IMALlama 17 points 1 day ago (2 children)

This is pretty cool.

This is the how-they-done-it paragraph. Essentially, they printed mechanical logic gates by taking advantage of a conductive filament that grows/shrinks as it heats and cools. Cool!

The conductive filament the researchers used is Electrifi by Multi3D, which is PLA combined with copper micro-particles. A segment printed in this filament is normally very conductive due to the densely-packed particles, but as temperature increases (beginning around 40° C) the polymer begins to soften and undergoes thermal expansion. This expansion separates the copper particles, causing a dramatic increase in electrical resistance as electrical pathways are disrupted. That’s pretty neat, but what really ties it together is that this behavior is self-resetting, and reversible. As long as the PLA isn’t straight up melted (that is to say, avoids going over about 150° C) then as the material cools it contracts and restores the conductive pathways to their original low-resistance state. Neat!

[–] [email protected] 3 points 18 hours ago

So this is a 3D printed PTC thermistor. Very cool and potentially extremely useful for measuring temperatures within a housing which has never before been able to be done to my knowledge. This is potentially awesome for embedding in medical devices which by regulations cannot be above a specific temperature while in contact with the body.

That said, there is nothing "active" about it. Thermistors are, by definition, passive electronic components. Actives amplify, rectify, or supply electric energy while passives consume, store, and release supplied energy.

[–] SpaceNoodle 6 points 1 day ago (1 children)

$2.15/g, oof ouch owie

[–] papalonian 5 points 1 day ago (1 children)

Of course that's insanely expensive compared to our economy packs of standard PLA, but consider how much conductive filament one would need in comparison to normal filament for a project.

I'm aware that everything is in the realm of hypotheticals and prototypes, but even if the final product is significantly more expensive than standard filament, it's not like you'll need to be able to print entire parts out of it, just the electric traces.

[–] IMALlama 4 points 1 day ago (2 children)

I don't see this being practical beyond a "neat" any time soon. Because it relies on thermal expansion and contraction it won't be very fast to cycle. It's also physically pretty long/wide, so a more traditional IC or microcontroller would likely be a better choice unless it's super thin.

This is still cool, but I am failing to see a practical application.

If/when they're able to print transistors it will be a lot more interesting.

[–] Sgarcnl 2 points 1 day ago* (last edited 1 day ago)

What if you just put some fans on it to keep it below 40? It could become more reliable at the expense of requiring a bit more cooling.

[–] papalonian 2 points 1 day ago

Oh, I agree completely. I don't think the tech as-is should be being priced at all. What I'm saying is, even if this product does come to fruition, it likely will still be incredibly expensive compared to normal filament, but the amount one would need to use in a project is very small comparatively.