Synthetic Gel to Make Soft Shape-Changing Robot

Researchers at the University of Pittsburgh have designed a synthetic polymer gel that can utilise internally generated chemical energy to undergo shape-shifting and self-sustained propulsion.

"In biology, directed movement involves some form of shape changes, such as the expansion and contraction of muscles. So we asked whether we could mimic these basic interconnected functions in a synthetic system so that it could simultaneously change its shape and move," said lead author Anna C. Balazs, distinguished professor of chemical and petroleum engineering.

The researchers looked at the single-celled organism euglena mutabilis, which processes energy to expand and contract its shape in order to move.

To mimic the euglena's mobility, they looked to polymer gels containing spirobenzopyran (SP) since these materials can be morphed into different shapes with the use of light, and to Belousov-Zhabotinsky (BZ) gels, a material first fabricated in the late 1990s that not only undergoes periodic pulsations, but also can be driven to move in the presence of light.

"The BZ gel encompasses an internalised chemical reaction so that when you supply reagents, this gel can undergo self-sustained motion," said co-author Olga Kuksenok.

The benefit of using polymer gels instead of metals and alloys to build a robot is that it greatly reduces its mass, improves its potential range of motion and allows for a more "graceful" device.

"To put it simply, in order for a robot to be able to move more autonomously in a more biomimetic way, it's better if it's soft and squishy," Kuksenok said.

The study was published in the journal Scientific Reports, published by Nature.