Naturally occurring hydrogel mixes water and organic gummy material to allow sea creatures to form durable bonds with their surroundings, or even with passing vessels. The synthetic superglue created in MIT’s Mechanical Engineering lab is more than 90 percent water, and still mimics the durability and versatility of natural hydrogel. It is a mostly transparent adhesive, and its rubbery quality means it can bond any number of materials, including glass, silicon, ceramics, aluminum, titanium and steel.
Durability is an obviously important aspect of inventing a new adhesive solution, but underwater durability is a category all its own. The strength of this hydrogel superglue is one thing, but its water-based constitution also makes it uniquely useful for underwater purposes, like protective coatings on the surfaces of boats, ships, and submarines. What’s more, the fact that that the synthetic hydrogel is 90 percent water makes it biocompatible, and well suited for use in health industry tools like biomedical coatings for internal catheters and sensors.
MIT says their hydrogel superglue is as strong as the bond between tendon and cartilage on bone in the body, and a wide range of durability tests prove that assertion. The team was able to hang a 55-pound weight from two plates of glass glued together with a small area of hydrogel. When hydrogel was applied to a silicon wafer, smashing the silicon caused the pieces to shatter but not disperse, thanks to the strength of the adhesive. On average, researchers on the MIT team found that their hydrogel was much stronger than other existing hydrogel applications, measuring strength up to 1,000 joules per square meter.
Hydrogel is as strong as heavy duty industrial glue, but since it is made mostly of water, it remains soft and pliable. In the future, the tendon and cartilage comparison could go further than a simple demonstration of the hydrogel’s strength. Because hydrogel maintains its softness in spite of its strength and durability, the MIT team is exploring ways to use the adhesive as a synthetic flexible joint in soft robotics development and bioelectronics.