Robots made from hydrogel and almost invisible to the naked eye have captured a live fish underwater.
Scientists made limbs that moved when water was pumped in and out of them, capable of generating a few newtons of force in a second.
This means they can perform some quick and impressive tasks, such as ‘kicking’ a ball underwater or grabbing and releasing a fish.
Hydrogel is a tough, rubbery, translucent material composed largely of water. Each robot consists of hollow, precisely designed hydrogel structures, connected to rubbery tubes. When researchers pump water in, the structures quickly inflate in orientations that enable the robots to curl up or stretch out.
A team from MIT has made several types of hydrogel robots, including a finlike structure that flaps back and forth, an articulated appendage that makes a kicking motion and a soft, hand-shaped robot that can squeeze and relax.
The robots are powered by and made almost entirely of water, so are very difficult to see when deployed under water.
“Hydrogels are soft, wet, biocompatible and can form more friendly interfaces with human organs,” said Xuanhe Zhao, associate professor of mechanical engineering, civil and environmental engineering, and team leader at MIT.
The team is currently looking to adapt hydrogel robots for medical applications.
“We are actively collaborating with medical groups to translate this system into soft manipulators such as hydrogel ‘hands,’ which could potentially apply more gentle manipulations to tissues and organs in surgical operations,” said Zhao.
Durable, flexible, strongly bondable and biocompatible hydrogels may well be the ideal materials for use in soft robotics.
Zhao pointed out that as hydrogels are mostly composed of water, they are naturally safer to use in a biomedical setting than other soft robot candidates.
Zhao, graduate students Hyunwoo Yuk, Shaoting Lin and Chu Ma, postdoc Mahdi Takaffoli, and associate professor of mechanical engineering Nicholas X. Fang recently published their findings in the journal Nature Communications.