A Cheerios-inspired robot that emits alcoholic fuel using fluorescent dye.
Jackson K. Wilt et al. 2024
The same phenomenon as beetles floating on a pond and Cheerios growing in clusters. You can combine them inside a cereal bowl to make a small floating robot.
One such effect, the Marangoni effect, occurs when a fluid with a low surface tension spreads rapidly across the surface of a fluid with a high surface tension. To take advantage of this effect, stenus There are beetles that have evolved to fly around ponds by secreting a substance called stenusin, and toy boats that run on soap.
To explore how engineers can use this, jackson wilt Harvard University and his colleagues 3D printed round plastic pucks about 1 centimeter in diameter. Each had an air chamber for buoyancy and a small fuel tank containing 10 to 50 percent alcohol, which has a lower surface tension than water. Alcohol gradually leaks out of the pack and the pack moves across the water’s surface.
The researchers used alcohol, which evaporates, as fuel, unlike soap, which ends up contaminating the water and ruining the Marangoni effect. It turns out that the stronger the alcohol, the better the results. “The beer would be pretty bad,” Wilt says. “Vodka is probably the best thing you can use. Absinthe…that’s a lot of propulsion.” At top speed, the robot moves at 6 centimeters per second, and some experiments propelled the puck for as long as 500 seconds. It has been confirmed that
By printing pucks with multiple fuel outlets and gluing them together, researchers can also create larger devices that can make wide curves or rotate in place. Using multiple packs also allows researchers to study the “Cheerios effect,” where cereals and other similar floating objects cluster together. This occurs because they form a meniscus, or curved surface, in the fluid, and these surfaces are attracted to each other.
Wilt said 3D printed devices could be useful in education to help students intuitively understand concepts related to surface tension, but could also be carefully designed to produce more complex and elegant behavior. If this is possible, it can be expected to be applied to environmental and industrial processes.
For example, if there is a substance that needs to be dispersed throughout the environment and also acts as a suitable fuel, the robot can automatically disperse it around it. “Say you have a body of water that needs to release a chemical and you want it to be distributed more evenly, or say you have a chemical process that needs to deposit material over time,” Wilt says. . “I feel like there’s some really interesting behavior here.”
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