2019-02-22 L231

Scientists at the Massachusetts Institute of Technology have said lobsters could be key to creating super-strong and flexible armor in the future. The underbellies of these famous crustaceans contain a translucent membrane that scientists have now found to be one of the toughest hydrogels in the world.

Hydrogels are gels that are normally composed of one or more polymers suspended in water. For decades, they have been investigated for their biomedical qualities—they hold huge potential for applications relating to wound healing and bone regeneration, for example.

More recently, scientists have started to look at hydrogels for their military applications—from high-tech winter gloves that are able to absorb sweat and other liquid to keep hands warm and dry, to medical dressings that could stop bleeding on the battlefield.

Researchers at MIT are now looking at a specific hydrogel found in lobsters. The translucent soft membrane found on the underside of these marine creatures has been analyzed by scientists, who have found it is made of a layer of “plywood-like structure” that makes it highly resilient to cuts. It is also very flexible and stretchy, allowing the lobster to move its tail around.
Publishing their research in the journal Acta Biomaterialia, the team found the membrane on the belly of the American Lobster is the toughest material of all known natural hydrogels. In terms of strength, it is comparable to industrial rubber that is used to make car tires and conveyor belts.

Its strength and flexibility, the team say, make it an ideal material to use as a blueprint for body armor. “We think this work could motivate flexible armor design,” Ming Guo, one of the study authors, said in a statement. “If you could make armor out of these types of materials, you could freely move your joints, and it would make you feel more comfortable.”

Guo started to study lobsters after noticing their unusual properties—their underbellies are particularly difficult to chew, for example. When they are swimming, they are able to move their joints and tails very fast, meaning they must have soft tissue connections. “But nobody has looked at the membrane before, which is very surprising to us,” he said.

The team carried out experiments on the membrane, and found it could be stretched to twice its normal length. It was also found to be resilient to small cuts. “We made scratches to mimic what might happen when they’re moving through sand, for example,” Guo said. “We even cut through half the thickness of the membrane and found it could still be stretched equally far. If you did this with rubber composites, they would break.”

The team is now hoping to understand the mechanisms underlying the strength of the lobster membrane. “We think this membrane structure could be a very important reason for why lobsters have been living for more than 100 million years on Earth. Somehow, this fracture tolerance has really helped them in their evolution,” Guo said.

Concluding, they said: “The knowledge learned from the soft membrane of natural lobsters sheds light on designing synthetic soft, yet strong and tough materials for reliable usage under extreme mechanical conditions, including a flexible armor that can provide full-body protection without sacrificing limb mobility.”