Plastic Can Walk on Its Own Now
Plastic has taken its first, snail-pace steps using light stimuli instead of coded programming.
Researchers hope to continue destigmatizing plastic for use in robotics and environmentally friendly products, including teaching consumers about better recycling.
The walking plastic is more like activated computer circuitry, using changing stimuli to conduct actions.
Scientists have trained plastic to walk on its own using a combination of photosensitive bio-inspiration and light-reactive coatings. Look at it go!
The scientists use an analogy to Pavlov’s dog, but the truth is more like how a plant bends toward the sun and away from darkness. Light and heat reaction induce constriction or expansion that bends joints and enables motion. For plants, any Pavlovian reaction is built in because the light itself is the food. But the plastic robot is trained to respond to light even after the heat stimulus is removed, which is the Pavlovian side.
One reason the walking plastic robot is a big deal is that it isn’t computer-programmed. There’s no code or algorithm in the traditional sense. In a way, the walking plastic is like the conductive circuitry that powers the computer rather than its programs. At the most basic level, coding is executed in alternating bursts of electrical energy enabled by conductors and insulators, not the words, code, or even punchcards that are used to guide the electricity around. Like a “computer” used to only be a person, a “programmer” also refers to a piece of hardware that designs circuitry to execute a certain way.
To condition a non-coded material to execute commands, scientists used the way plants and animals are conditioned to respond to stimuli like light, other sensory data, and danger. “Learning can be considered as a sequence of processes whereby a biological system or organism modifies its behavior upon past experiences,” the researchers write. By keeping their plastic walker extremely simple and limiting its stimuli very carefully, they adapted natural organism learning to plastic.
First, the plastic experienced heat separately and responded to that. The researchers exposed it to light separately as well, and nothing happened. Then the plastic was “trained” by repeated exposure to both light and heat simultaneously. When heat was taken away, the material continued to respond only to light.
By combining light arrays with responsive materials, the scientists have taught a plastic item how to learn a very simple, but real behavior.
“We propose that concepts inspired by the simplest forms of associative learning can act as a guide to design adaptive functional materials,” they conclude.
This complex setup seems analogous to how sensory input and electrical zaps seem to be what guide the human brain, with dozens of “peripheral devices” like nerve-laced skin surface and stereoscope vision combining to form not just a picture of the world, but a plan to interact with it.
Tampere University in Finland, where this study originated, has an applied sciences program with a focus on studying and demystifying plastics. There is no need to skimp on plastic in the future, scientists from the program said in November, citing plastic’s recyclability and eclectic use cases. Recycling terms are confusing to people and haven’t been helped by industry messaging: “Biobags are often made of starch and they are thus biobased and biodegradable. In order to make a mess of concepts, there is also the term compostability. It is not the same as standard-based biodegradability.”
Indeed, the term plastic as an adjective means to stay flexible and formable, whether in literal plastic or the human brain. Carefully prepared plastic has taken its first steps, and lightweight, biodegradable plastics could mean the difference in a less wasteful future, lighter-weight space vehicles, and much more. We may just first have to undo our conditioning that all plastic is bad.
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