A step toward fully 3D-printed active electronics

Reading the article, it looks like so far they only have a working resettable fuse (a passive device), and only hypothesize that a transistor was possible with the copper-infused PLA filament. So no actual working active electronics.

And from the paper linked in the article[1], it seems the actual breakthrough is the discovery that copper-infused PLA filament exhibits a PTC-effect, which is noteworthy, but definitely not "3D-Printed Active Electronics" newsworthy.

[1] https://www.tandfonline.com/doi/full/10.1080/17452759.2024.2...

Hang on, can you explain why this is passive and not active?

> Harnessing the described phenomenon, we created the first semiconductor-free active electronic devices fully 3D printed via material extrusion. We demonstrate this breakthrough through the implementation of monolithically 3D-printed logic gates.

They've created a Polymeric Positive Temperature Coefficient (PPTC) device. As it heats up the resistance gets very high very abruptly.

While it is non-linear, diodes are also considered passive devices[2], as active is taken to mean electrical control of current flow.

In this case one could induce current control through thermal means, ie an adjacent heating element, and if you potted that in a box I guess you could argue the box is an active device. But not the PPTC itself.

[1]: https://m.littelfuse.com/~/media/electronics/technical_paper...

[2]: https://wiki.analog.com/university/courses/electronics/text/...

> active is taken to mean electrical control of current flow

Is a transformer an active device? Asking because current in one loop can control current in the other loop.

From there, are two copper wires an active device?