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Tech & Science
MIT scientists have transformed a 1985 patent into the “Y-zipper,” enabling rapid shifts from flexible to rigid forms in objects like tents, robots, and medical devices.
In 1985, an electrical engineer at Polaroid named William Freeman submitted a patent for a three-sided zipper capable of converting soft materials into rigid structures. Although the technology to realize this concept was unavailable at the time, MIT researchers have now brought the idea to life with the creation of the “Y-zipper.”
Freeman’s original invention featured a triangular fastener with three flexible strips lined with wooden “teeth” that, when zipped together, formed a rigid tube. Intended to help objects such as tents, chairs, and bags transition from collapsible to sturdy forms, the concept was initially rejected despite being patented and stored by Freeman for decades.
Recently, MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) revisited Freeman’s design while exploring ways to produce objects with adjustable stiffness. Prior techniques for stiffness modulation were either irreversible or required manual assembly. CSAIL developed an automated design tool alongside the Y-zipper, which can be fabricated via 3D printing using plastics and integrated into various applications.
According to Jiaji Li, a CSAIL postdoctoral researcher and lead author of the project’s open-access paper, the Y-zipper enables rapid transitions between flexible and rigid states in complex items, surpassing the capabilities of traditional zippers designed for flat materials like clothing.
The CSAIL software allows users to customize the Y-zipper’s closed shape by adjusting strip lengths, bend directions, and angles. Four motion patterns are available: straight, arched, coiled, and twisted. Physically, the zipper resembles a squid with three tentacle-like arms when open, and it contracts into a tighter form such as a rod when zipped shut.
This transformation facilitates quicker assembly of outdoor equipment. For example, pitching a tent with the Y-zipper took one minute and 20 seconds, compared to six minutes without it. Each arm attaches to a tent side, providing structural support by snapping the canopy into place.
The zipper’s ability to switch smoothly between soft and rigid states also shows promise for adjustable wearables, especially medical devices. The team demonstrated this by wrapping a Y-zipper around a wrist cast, allowing the wearer to loosen it during the day and tighten it at night to aid recovery.
Beyond manual operation, the Y-zipper can be motorized to automate shape changes. CSAIL researchers attached a motor to the fastener to create an adaptive robotic quadruped capable of altering leg length by opening or closing the zipper. Such robots could adapt to uneven terrain by adjusting their posture.
Motor-driven Y-zippers were also used to construct kinetic art installations, including a winding flower that “bloomed” when zipped closed by a stationary motor.
The research team tested the Y-zipper’s durability using two common 3D printing plastics: polylactic acid (PLA) and thermoplastic polyurethane (TPU). Load tests showed PLA supported heavier weights, while TPU offered greater flexibility. In cyclic testing, the zipper endured approximately 18,000 open-close cycles before failure.
Simulations indicated the elastic structure of the Y-zipper distributes stress evenly under load, contributing to its longevity. The researchers are exploring the use of stronger materials such as metal and scaling up the zipper size, though current 3D printing capabilities limit larger fabrication.
Li highlighted unexplored applications, including space exploration, where Y-zipper arms could be integrated into spacecraft for collecting rock samples. The fastener may also assist rapid deployment of shelters or medical tents during disaster relief or rescue operations.
Zhejiang University assistant professor Guanyun Wang, who was not involved in the study, praised the approach for bridging soft and rigid states and providing a scalable fabrication method that could advance embodied intelligence design.
The research was presented at the ACM’s Computer-Human Interaction (CHI) conference in April 2026 and was partially supported by a postdoctoral fellowship from Zhejiang University and the MIT-GIST Program.
