Hydrogel discs have the ability to increase in area by up to 100 times when stretched. These highly elastic materials can stretch up to 15 times their initial length, making them ideal for use in robotic grippers or tendons. The secret behind this material’s stretchiness is its polymer molecules linked by water molecules, but they often do not return to their original shape when overstretched.

Recently, Lili Chen and her team at Tsinghua University in Beijing have developed a new type of hydrogel that not only stretches but also maintains its original shape. They accomplished this feat by inserting pearl-necklace chains into the hydrogel structure, made of coiled polymer beads connected by a chain of carbon atoms. These chains can unfurl under strain and rewind when the strain is released.

To create these chains, the researchers dried out the hydrogel so that the polymer chains were attracted to themselves rather than to water molecules. The hydrogel could stretch to nearly 5 meters before quickly returning to its original length. A 2-centimeter-wide disc of the hydrogel could increase 100 times in area before returning to its original size.

The researchers also created inflatable robotic grippers from the hydrogel, designed to handle delicate objects like strawberries. These grippers were extremely damage resistant, able to withstand being stood on or pierced with a needle. Zehuan Huang at Peking University praised the work, stating that this hydrogel represents a major breakthrough in high-performance polymeric materials and will inspire interest in using hyper-elastic gels in soft robotics.

In conclusion, this new type of hydrogel has shown great potential for use in various fields such as robotics and medicine due to its unique properties of stretchability and shape memory. Further research on this material could lead to significant advancements in soft robotics and biomedical engineering.