This engine may not replace the fuel in your Hummer, but this machine could represent the first step toward bacterial spore- and evaporating water-powered devices. Into the bargain, building the engine would only cost $5 in estimate.
In a study published in Tuesday in Nature Communications, researchers at the Columbia University presented several devices powered by the shrinking and swelling of bacterial spores in response to changes in humidity. The initial prototypes may look like a child’s play, but the researchers are convinced that they have only just begun to tap the energy potential of the technology.
Lead author and associate professor Ozgur Sahin started this work nearly a decade ago, when he participated in a project studying bacterial spores. Sahin was contributing a high-tech microscope his lab had developed, but what he learned in his endeavor inspired him to turn his focus to these spores.
“People before us had shown that the spores change shape in response to humidity,” Sahin told The Post. “They shrink when they’re dry and expand when exposed to moisture. But in our studies, we found them to be surprisingly rigid. That told us that this shape change must come with a lot of energy. In the beginning, I was just amazed at this biological substance. But then I thought, there must be applications for this.”
In his previous studies, Sahin showed the spores are capable of harvesting large quantities of energy from their interaction with water. To make this work move forward, he realized the need to show the energy storage and release in action. “I sketched out this idea, where a device was placed on the surface of a reservoir of water,” he said. “If you made shutters that could allow moisture through or block it, you could control the humidity of the spores inside, making them cyclically expand and contract.”
He then calculated that the device could be self-regulating if the spores were rigged to be attached to the shutters, and when spores get too dry, they would shrink up and eventually close the shutters, creating a humid environment that would lead the spores to expand and open the shutters, ad infinitum.
By coating plastic in the spores, researchers created artificial muscles that extend and contract in response to a change in humidity. In this way, the muscles power the evaporation engine by cyclically extending and contracting on the surface of water, lifting a weight in the process (Xi Chen).
In the latest study, his team manufactured together tools that would produce lifting and piston-like motions by using the natural aspect of the spores—which are usually created in great amounts for probiotic additives—in order to expand and contract. Strips of plastic contained in those devices were coated in the spores to make their reaction easier to harness.
The implements were also able to create enough energy to turn on light bulbs. Sahin thought of this application to be very helpful in giving power lights on devices that stays on the sea, for example, hydrothermal power generators or oil rigs. He even explained that his group made a lot of shortcuts to produce a model that worked to see a big upturn in the energy output faster than expected.
Using a common Elmer’s Glue, the spores were pasted to the tape, but that bond cannot withstand the power that the spores are capable of producing; using a better adhesive could help the machines work more efficiently.
Sahin said hypothesis has it that for a much lower cost, bacterial spores could create a lot of energy compared to per square foot than wind farms, which until now has not been demonstrated in a working apparatus. While he together with the team continue to work on improving the engines, he hopes the low cost of the prototypes he has created will inspire some clever application of the (very cool) marvel in the future.
“Our devices may seem like toys, but a lot of big technologies start out that way,” Sahin said.