A balding man in a blue suit and tie sits behind rows of plants on tables. A bright yellow watering can is close to the camera and out of focus.

Phytoremediation To Clean The Environment And Mine Critical Materials

February 28, 2025 by Navarre Bartz 10 Comments

Nickel contamination can render soils infertile at levels that are currently impractical to treat. Researchers at UMass Amherst are looking at how plants can help these soils and source nickel for the growing EV market.

Phytoremediation is the use of plants that preferentially hyperaccumulate certain contaminants to clean the soil. When those contaminants are also critical materials, you get phytomining. Starting with Camelina sativa, the researchers are looking to enhance its preference for nickel accumulation with genes from the even more adept hyperaccumulator Odontarrhena to have a quick-growing plant that can be a nickel feedstock as well as produce seeds containing oil for biofuels.

Despite being able to be up to 3% Ni by weight, Odontarrhena was ruled out as a candidate itself due to its slow-growing nature and that it is invasive to the United States. The researchers are also looking into what soil amendments can best help this super Camelina sativa best achieve its goals. It’s no panacea for expected nickel demand, but they do project that phytomining could provide 20-30% of our nickel needs for 50 years, at which point the land could be turned back over to other uses.

Recycling things already in technical cycles will be important to a circular economy, but being able to remove contaminants from the environment’s biological cycles and place them into a safer technical cycle instead of just burying them will be a big benefit as well. If you want learn about a more notorious heavy metal, checkout our piece on the blessings and destruction wrought by lead.

Continue reading “Phytoremediation To Clean The Environment And Mine Critical Materials” →

Building An Interferometer With LEGO

February 28, 2025 by Lewin Day 14 Comments

LEGO! It’s a fun toy that is popular around the world. What you may not realize is that it’s also made to incredibly high standards. As it turns out, the humble building blocks are good enough to build a interferometer if you’re so inclined to want one. [Kyra Cole] shows us how it’s done.

The build in question is a Michelson interferometer; [Kyra] was inspired to build it based on earlier work by the myphotonics project. She was able to assemble holders for mirrors and a laser, as well as a mount for a beamsplitter, and then put it all together on a LEGO baseboard. While some non-LEGO rubber bands were used in some areas, ultimately, adjustment was performed with LEGO Technic gears.

Not only was the LEGO interferometer able to generate a proper interference pattern, [Kyra] then went one step further. A Raspberry Pi was rigged up with a camera and some code to analyze the interference patterns automatically. [Kyra] notes that using genuine bricks was key to her success. Their high level of dimensional accuracy made it much easier to achieve her end goal. Sloppily-built knock-off bricks may have made the build much more frustrating to complete.

We don’t feature a ton of interferometer hacks around these parts. However, if you’re a big physics head, you might enjoy our 2021 article on the LIGO observatory. If you’re cooking up your own physics experiments at home, don’t hesitate to drop us a line!

Thanks to [Peter Quinn] for the tip!

A dark walnut table sits in the sun in what appears to be a field. Voids in the natural wood slab have been filled with shiny bronze, and a bundle of copper wire sits upon the edge of the table in a jaunty artistic fashion.

A Different Take On The River Table Does It In Bronze

February 28, 2025 by Navarre Bartz 6 Comments

River tables are something we’ve heard decried as a passé, but we’re still seeing some interesting variations on the technique. Take this example done with bronze instead of epoxy.

Starting with two beautiful slabs of walnut, [Burls Art] decided that instead of cutting them up to make guitars he would turn his attention to a river table to keep them more intact. Given the price of copper and difficulty in casting it, he decided to trim the live edges to make a more narrow “river” to work with for the project.

Since molten copper is quite toasty and wood likes to catch on fire, he wisely did a rough finish of the table before making silicone plugs of the voids instead of pouring metal directly. The silicone plugs were then used to make sand casting molds, and a series of casting trials moving from copper to bronze finally yielded usable pieces for the table. In case that all seems too simple, there were then several days of milling and sanding to get the bronze and walnut level and smooth with each other. The amount of attention to detail and plain old elbow grease in this project is impressive.

We’ve seen some other interesting mix-ups of the live edge and epoxy formula like a seascape night light or this river table with embedded neon. And if you’re looking to get into casting, why not start small in the microwave?

Continue reading “A Different Take On The River Table Does It In Bronze” →

Cheap Fiber Optic Wand Toy Becomes Tiny Weird Display

February 28, 2025 by Lewin Day 11 Comments

If you’ve ever seen those cheap LED fiber optic wands at the dollar store, you’ve probably just thought of them as a simple novelty. However, as [Ancient] shows us, you can turn them into a surprisingly nifty little display if you’re so inclined.

The build starts by removing the fiber optic bundle from the wand. One end is left as a round bundle. At the other end, the strands are then fed into plastic frames to separate them out individually. After plenty of tedious sorting, the fibers are glued in place in a larger rectangular 3D-printed frame, which holds the fibers in place over a matrix of LEDs. The individual LEDs of the matrix light individual fibers, which carry the light to the round end of the bundle. The result is a tiny little round display driven by a much larger one at the other end.

[Ancient] had hoped to use the set up for a volumetric display build, but found it too fragile to be fit for purpose. Still, it’s interesting to look at nonetheless, and a good demonstration of how fiber optics work in practice. As this display shows, you can have two glass fibers carrying completely different wavelengths of light right next to each other without issue.

We’ve featured some other great fiber optic hacks over the years, like this guide on making your own fiber couplings. Video after the break.

Continue reading “Cheap Fiber Optic Wand Toy Becomes Tiny Weird Display” →

Low-Resolution Fluid Simulation On An ESP32

February 28, 2025 by Lewin Day 2 Comments

Fluid simulations are a key tool in fields from aerospace to motorsports and even civil engineering. They can be three-dimensional and complicated and often run on supercomputer clusters bigger than your house. However, you can also do simple two-dimensional fluid simulations on very simple hardware, as [mircemk] demonstrates.

This build is almost like a simple toy that displays particles rolling around and tumbling as you turn it one way or the other. Behind the scenes, an ESP32 is running the show, simulating a group of particles responding to gravity in a fluid-like manner. The microcontroller is hooked up with an 3-axis gyroscope and accelerometer, which it uses to track motion and influence the motion of the particles in turn. The results of the simple fluid simulation are displayed on a screen made up of a 16 x 16 matrix of WS2812B addressable RGB LEDs, which add enough color to make the build suitably mesmerizing.

There’s something compelling about turning the display and watching the particles tumble and flow, particularly when they’re all set to different colors. [mircemk] also gave the build the ability to operate in several different modes, running “sand,” “liquid” and “gas” simulations and with dynamic coloring to boot.

We’ve seen some great videos from [mircemk] before, too, like this sensitive metal detector rig. Continue reading “Low-Resolution Fluid Simulation On An ESP32” →

Tech In Plain Sight: Shopping Cart Locks

February 28, 2025 by Al Williams 48 Comments

Shopping carts are surprisingly expensive. Prices range up to about $300 for a cart, which may seem like a lot, but they have to be pretty rugged and are made to work for decades. Plastic carts are cheaper, but not by much.

And carts have a way of vanishing. We’ve seen estimates that cart theft costs hundreds of millions of dollars worldwide annually. To stem the tide, stores sometimes pay a reward to people to round up carts off the street and return them to the store — it’s cheaper than buying a new one. That led [Elmer Isaacks] to patent a solution to this problem in 1968.

The [Isaacks] system used lots of magnets. A cart leaving the store had a brake that would be armed by running over a magnet. Customers were expected to follow a path surrounded by magnets to prevent the brake from engaging. If you left the track, a rod passing through the wheel locked it.

A third magnet would disarm the brake when you entered the store again. This is clever, but it has several problems. First, you have to insert magnets all over the place. Second, if someone knows how the system works, a simple magnet will hold the brake off no matter what. Continue reading “Tech In Plain Sight: Shopping Cart Locks” →

Hackaday Podcast Episode 310: Cyanotypes, Cyberdecks, And The Compass CNC

February 28, 2025 by Kristina Panos 4 Comments

This week, Hackaday’s Elliot Williams and Kristina Panos met up in a secret location with snacks to bring you the latest news, mystery sound, and of course, a big bunch of hacks from the previous week.

First up in the news, and there’s a lot of it: we announced the Hackaday Europe 2025 workshops and a few more speakers, though the big keynote announcement is still to come. In case you missed it, KiCad 9 moved up into the pro league, and finally, we’re hiring, so come join us in the dungeon.

On What’s That Sound, Kristina didn’t get close at all, but at least had a guess this time. That’s okay, though, because nobody got it right! We’re still giving a t-shirt away to [Dakota], though, probably because Elliot has a thing for using random number generators.

Then it’s on to the hacks and such beginning with a beautiful handheld compass CNC and cyanotype prints made with resin printer’s UV light. After that, we take a look at open-source random numbers, a 3D-printed instant camera, and a couple of really cool cyberdecks. Finally, we discuss whether DOOM is doomed as the port of choice in this day and age, and kvetch about keyboards.

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Download in DRM-free MP3 and savor at your leisure.