A decades-old patent from MIT Professor Bill Freeman inspired the new “Y-zipper,” a three-sided fastener that can snap gear, robots, and art into shape with the push of a button.
Long before shape-shifting robots and self-assembling structures became engineering goals, one MIT professor had already imagined a zipper that could transform floppy materials into rigid forms on demand. The problem? In 1985, the technology needed to build it simply didn’t exist.
That year, the Innovative Design Fund placed an ad in Scientific American offering up to $10,000 for inventive ideas in clothing, textiles, and home design. William Freeman PhD ’92 — then an electrical engineer at Polaroid and now an MIT professor — responded with an unusual concept: a three-sided zipper that could make objects instantly switch between soft and stiff states. Instead of fastening jackets or pants, Freeman envisioned it helping items like tents, chairs, and bags collapse flat for transport and then lock themselves into sturdy 3D structures when zipped together.
His prototype looked like a triangular version of a conventional zipper. Three flexible strips lined with narrow wooden “teeth” could be drawn together by a sliding mechanism, forming a rigid triangular tube. The idea was rejected, but Freeman patented the invention and stored the prototype in his garage, convinced it might someday find a purpose.
Nearly four decades later, researchers at MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) returned to the idea as they looked for ways to create objects with “tunable stiffness.” Earlier methods for changing stiffness were either difficult to reverse or required assembly by hand. CSAIL responded by creating both an automated design tool and an adaptable fastener called the “Y-zipper.”
The software lets users design customized three-sided zippers, which are then fabricated automatically with plastics in a 3D printer. The resulting fasteners can be attached to or built into camping equipment, medical devices, robots, and art installations to make assembly easier.
“A regular zipper is great for closing up flat objects, like a jacket, but Freeman ideated something more dynamic. Using current fabrication technology, his mechanism can transform more complex items,” says MIT postdoc and CSAIL researcher Jiaji Li, who is a lead author on an open-access paper presenting the project. “We’ve developed a process that builds objects you can rapidly shift from flexible to rigid, and you can be confident they’ll work in the real world.”
Y-Zipper: 3D Printing Versatile-Inflexible Transitions in One Click on. Credit score: MIT
Why zippers?
In CSAIL’s software program, customers can determine what the fastener will appear to be as soon as it’s closed. They will set the size of every strip and select the route and angle of its bends. They will additionally choose from 4 fundamental movement patterns that decide the closed form: straight, bent like an arch, coiled like a spring, or twisted like screws.
The completed Y zipper seems to vary form within the bodily world. When open, it could actually unfold out like a squid with three prolonged tentacles. When zipped shut, it pulls right into a tighter construction (like a rod, for example). That flexibility could possibly be helpful for journey and out of doors gear. Pitching a tent alone can take as much as six minutes, however with assist from the Y zipper, the method took one minute and 20 seconds. Every arm attaches to a facet of the tent, supporting the construction from above so the fastener successfully snaps the cover into place.
That clean shift between gentle and inflexible states might additionally assist create extra adjustable wearables, particularly for medical use. The staff wrapped a Y zipper round a wrist forged so the wearer might loosen it through the day and shut it at night time to assist forestall additional damage. In that setup, a tool that usually feels inflexible can turn into extra adaptable to a affected person’s consolation and wishes.
The system may also assist construct know-how that strikes with the press of a button. After fabrication, a motor will be hooked up to the Y zipper to automate the closing course of. The researchers used this strategy to make an adaptive robotic quadruped. Such a robotic might at some point change the size of its legs, pulling itself into taller limbs or opening the fastener to remain nearer to the bottom. Quick form modifications like these might assist robots transfer throughout uneven environments similar to canyons or forests. Motor-driven Y zippers may also create transferring artwork installations. In a single instance, the staff constructed an extended winding flower that “bloomed” when a stationary motor zipped the gadget closed.
Mastering the fabric
Li and his colleagues noticed many attainable makes use of for the Y zipper, however they nonetheless wanted to check whether or not it might maintain up underneath repeated use.
The staff started with stress exams. They in contrast polylactic acid (PLA) and thermoplastic polyurethane (TPU), two plastics commonly used in 3D printing. A machine bent the Y zippers downward, showing that PLA could carry heavier loads, while TPU was more flexible.
In a separate test, CSAIL researchers used an actuator to repeatedly open and close the fastener until it failed. The Y zipper finally broke after about 18,000 cycles. According to 3D simulations, its durability comes from its elastic structure, which spreads stress more evenly under heavy loads.
Even with those results, Li sees room for a stronger version made from tougher materials such as metal. The team may also scale the zippers up for larger projects, although their current 3D printing system cannot yet produce that size.
Li also points to uses that remain largely unexplored. In space exploration, Y zipper arms could be integrated into a spacecraft and used to collect nearby rock samples. Similar fasteners could also be built into structures designed for rapid assembly, helping relief teams quickly deploy shelters or medical tents after disasters or during rescue operations.
“Reimagining an everyday zipper to tackle 3D morphological transitions is a brilliant approach to dynamic assembly,” says Zhejiang University assistant professor Guanyun Wang, who wasn’t involved in the paper. “More importantly, it effectively bridges the gap between soft and rigid states, offering a highly scalable and innovative fabrication approach that will greatly benefit the future design of embodied intelligence.”
Reference: “Y-zipper: 3D Printing Flexible–Rigid Transition Mechanism for Rapid and Reversible Assembly” by Jiaji Li, Xiang Chang, Mingming Li, Dingning Cao, Maxine Perroni-Scharf, Jeremy Mrzyglocki, Takumi Yamamoto, William Freeman and Stefanie Mueller, 13 April 2026, CHI ’26: Proceedings of the 2026 CHI Conference on Human Factors in Computing Systems.
DOI: 10.1145/3772318.3790723
Supported, in part, by a postdoctoral research fellowship from Zhejiang University and the MIT-GIST Program.
Disclosure: The researchers’ work was presented at the ACM’s Computer-Human Interaction (CHI) conference on Human Factors in Computing Systems in April.
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