First Look at Bifur-circuits, MIT’s 3D-Printed Blocks That Fold Into New Objects and Know Which Shape They’re In

Chairs stay chairs. Tables stay tables. Anything that needs to become both usually grows hinges, motors, and a tangle of wires that quit the first time you twist the thing the wrong way. Researchers at MIT’s Computer Science and Artificial Intelligence Lab spent years looking for a quieter option, and they landed on Bifur-circuits: a kit of 3D-printed blocks that snap together, fold into new stable poses, and keep an electrical map of whatever form they just became.

Each printed unit is one of these smart auxetic lattices, which are repeating designs that widen when stretched rather than pinched inwards. You can find one unit in three different positions. When you link a couple of these devices with some connector pieces, a new behavior emerges. Pushing or twisting past a specific point causes the entire assembly to snap into a new stance and lock it in place. That rapid change is identical to the mechanical ‘bifurcation’ that occurs when a weak plastic ruler finally gives way under strain. When you combine more and more blocks, the number of viable stable positions skyrockets, far beyond the three fixed shapes employed by the same scientists in their previous shape-shifting antenna research.

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Conductive filaments for the connectors are built into the units as you print the flexible plastic, and they remain linked even if the entire structure is stretched, squished, rotated, or bent whatever you wish. When neighboring blocks meet in different orientations, contact pads at the joints close in a unique circuit, giving each position its own electrical signature. Then, a small controller at the assembly’s root pokes about the connections, asking the units who they are and where they are in respect to one another, and creates a map of the entire thing, all without the need for any further wire between the units.

The difficult part was finding a filament that could flex back and forth thousands of times without losing the signal. The units have stretchy TPU hinges, stronger PLA connectors, and a unique conductive flex filament for the actual electrical connections. If you need a specific position to be locked in tightly, you may even insert tiny magnets into the pockets during the print. After 10,000+ compression cycles, we discovered that the electrical contact remained firm. Larger assemblies take longer to scan; twenty units or so can take a few seconds to generate a comprehensive map.

A tool in Fusion 360 allows you to specify the size, thickness, and stiffness of each joint before exporting the file to be printed on one of those multi-material machines. There is also some companion software that allows you to preview the assembly, detects the finished pose when it occurs, and then creates code so that another app can react to that pose. Parts come out the printer ready to clip together, and all you need to do using heat and solder is add a little board to the end that communicates with the rest of your system.

One functioning model became a piece of furniture with twenty-four units, expanding into a tea table, folding up into a chair with a storage hole, and collapsing flat to store itself. While the geometry changed, the item communicated with a display to determine its new position. A second piece was a game controller that could be folded one way to launch a racing game, another way to launch a washing game, and a third way to launch a balloon-inflating game. You can simply add or delete units, and that controller will evolve into something else entirely.
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