If you ever wished electrons would just behave, this one’s for you. A team from Tohoku, Osaka, and Manchester Universities has cracked open an interesting phenomenon in the chiral helimagnet α-EuP₃: they’ve induced one-way electron flow without bringing diodes into play. Their findings are published in the Proceedings of the National Academy of Sciences.

The twist in this is quite literal. By coaxing europium atoms into a chiral magnetic spiral, the researchers found they could generate rectification: current that prefers one direction over another. Think of it as adding a one-way street in your circuit, but based on magnetic chirality rather than semiconductors. When the material flips to an achiral (ferromagnetic) state, the one-way effect vanishes. No asymmetry, no preferential flow. They’ve essentially toggled the electron highway signs with an external magnetic field. This elegant control over band asymmetry might lead to low-power, high-speed data storage based on magnetic chirality.

If you are curious how all this ties back to quantum theory, you can trace the roots of chiral electron flow back to the early days of quantum electrodynamics – when physicists first started untangling how particles and fields really interact.

There’s a whole world of weird physics waiting for us. In the field of chemistry, chirality has been covered by Hackaday, foreshadowing the lesser favorable ways of use. Read up on the article and share with us what you think.

If you think shorting a transformer’s winding means big sparks and fried wires: think again. In this educational video, titled The Magnetic Bypass, [Sam Ben-Yaakov] flips this assumption. By cleverly tweaking a reluctance-based magnetic circuit, this hack channels flux in a way that breaks the usual rules. Using a simple free leg and a switched winding, the setup ensures that shorting the output doesn’t spike the current. For anyone who is obsessed with magnetic circuits or who just loves unexpected engineering quirks, this one is worth a closer look.

So, what’s going on under the hood? The trick lies in flux redistribution. In a typical transformer, shorting an auxiliary winding invites a surge of current. Here, most of the flux detours through a lower-reluctance path: the magnetic bypass. This reduces flux in the auxiliary leg, leaving voltage and current surprisingly low. [Sam]’s simulations in LTspice back it up: 10 V in yields a modest 6 mV out when shorted. It’s like telling flux where to go, but without complex electronics. It is a potential stepping stone for safer high-voltage applications, thanks to its inherent current-limiting nature.

The original video walks through the theory, circuit equivalences, and LTspice tests. Enjoy!

One can 3D print with conductive filament, and therefore plausibly create passive components like resistors. But what about active components, which typically require semiconductors? Researchers at MIT demonstrate working concepts for a resettable fuse and logic gates, completely 3D printed and semiconductor-free.

Now just to be absolutely clear — these are still just proofs of concept. To say they are big and perform poorly compared to their semiconductor equivalents would be an understatement. But they do work, and they are 100% 3D printed active electronic components, using commercially-available filament.

How does one make a working resettable fuse and transistor out of such stuff? By harnessing thermal expansion, essentially.

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!

So where does the heat required come from? Simply passing enough current through the junction will do the job. By carefully controlling the size and shape of traces (something even hobbyist filament-based 3D printers are very good at) this effect can be made predictable and repeatable.

The simpler of the two test components uses the resistance spike as a self-resetting fuse. The printed component is designed such that current above a threshold triggers a surge in resistance, preventing damage to some theoretical circuitry downstream. As long as the component is not destroyed by heating it to the point that it melts, it self-resets as it cools.

The transistor is a bit more interesting. By designing two paths so that they intersect each other, one can be used as a control path and the other as a signal path. Applying a voltage to the control path electrically controls the resistance of the signal path, effectively acting as a transistor. Researchers combined these basic transistors into NOT, AND, and OR gates. One is shown here.

This whole system is scalable, low-cost, and highly accessible to just about anyone with some basic equipment. Of course, it has some drawbacks. The switching speed is slow (seconds rather than nanoseconds) and being thermally-driven means power consumption is high. Still, it’s pretty nifty stuff. Check out the research paper for all the nitty-gritty details.

We’ve seen 3D printed triboelectric generators so it’s pretty exciting to now see printed active electronic components. Maybe someday they can be combined?