New ‘superglue’ could seal the deal for stretchable batteries, soft robots

Superglue is great for fixing busted bookshelves, suitcase wheels, and—of course—shoes. But what if you want to fuse something a little more jiggly, like the gel cushions used to pad crumbling spinal discs? You’d be out of luck, until now. That’s because scientists have created a new kind of glue that can bond hard and soft substances to hydrogels, Jello-like materials used in everything from medical devices to soft robots. Previously, researchers in these fields used an ultraviolet light treatment, but it could take up to an hour or more to attach the surfaces together. Now, a team of experimental physicists has invented a new adhesive, made of superglue’s main ingredient—cyanoacrylate—plus an organic compound that diffuses into the parts being fused, leading to a tough bond without brittle residue left behind. This nonsolvent delays the hardening of the glue just long enough to let it seep into each layer being pressed together, forming a bond within seconds. The hydrogel bond can hold up to 1 kilogram and stretch up to 2000%, the researchers report this week in Science Advances. That’s good news for spine docs and robotics buffs alike—not only can the new adhesive help build devices like this octobot, but it can also be used to deliver drugs through soft, permeable patches that adhere to the skin. It can also help researchers designing stretchable batteries and electronic skin, hydrogel-based electronic patches packed with sensors for taking vital signs and communicating with outside devices. The only downside? It won’t be on the market for another 3 to 5 years.