Reinventing the zipper

With an adaptable fastener designed at CSAIL, pitching a tent or adjusting the cast for a broken bone could be almost as easy as zipping your coat. The researchers, led by associate professor Stefanie Mueller, were inspired by an abandoned prototype for a three-sided zipper that William Freeman, PhD ’92 (now an MIT professor), patented in the mid-1980s. With software they created, people can design customized versions of this fastener to be 3D-printed in plastic. Its three flexible “arms” can then form different types of rigid objects when zipped together. Users can select the strips’ length and the direction and angle at which they’ll bend. They can also choose whether the zipped-up device will appear straight, bent, coiled, or twisted. A tent making use of the zipper takes just 80 seconds to set up. A wrist cast that incorporates it can be tightened and loosened as desired. A motor can even be added so that, for example, a robot’s leg heights could change with the push of a button. “A regular zipper is great for closing up flat objects, like a jacket, but Freeman ideated something more dynamic,” says MIT postdoc Jiaji Li, a lead author on a 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.”