A team of engineers has designed, by developing a new computational model, a synthetic polymer gel that can reconfigure its own shape and move using its own internally generated power.
University of Pittsburgh's Anna C. Balazs said that movement is a fundamental biological behavior, exhibited by the simplest cell to human beings. It allows organisms to forage for food or flee from prey, but synthetic materials typically don't have the capability for spontaneous mechanical action or the ability to store and use their own energy, factors that enable directed motion.
Balazs added that moreover in biology, directed movement involves some form of shape changes, such as the expansion and contraction of muscles. So they asked whether they could mimic these basic interconnected functions in a synthetic system so that it could simultaneously change its shape and move.
To mimic the euglena's mobility, researchers 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 internalized chemical reaction so that when you supply reagents, this gel can undergo self-sustained motion, Kuksenok explains, adding that researchers have previously created polymer chains with both the SP and BZ functionality, but this is the first time they were combined to explore the ability of "SP-BZ" gels to change shape and move in response to light.
As Balazs and Kuksenok noted, these systems are distinctive because they not only undergo self-bending or folding, but also self-propelled motion.
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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.
Kuksenok added that 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, noting that it's ability to grab and carry something isn't impeded by non-flexible, hard edges. You'd also like its energy source incorporated into the design so that it's not carrying that as extra baggage. The SP-BZ gel is pointing in that direction.
The study appears in the journal Scientific Reports, published by Nature.