It’s been a big month for cats: The Oatmeal proved feline superiority over human babies, they got their first dedicated tunes, and researchers from the Georgia Institute of Technology discovered that a cat’s surface area equals that of a ping pong table.
We admit, it’s a bit confusing. A house cat is clearly much smaller than a nine-foot (three meter) table, so how could their surface areas be the same? The answer lies in the fact that cats actually have more than one surface. In fact, they have millions. Every square inch of a cat’s body is covered in some 60,000 individual hairs, and while that might seem insignificant, their powers combined, fur adds an immense amount of surface area to an animal.
While that extra real estate certainly helps animals keep warm, it also means more space for dirt, dust, and pollen to accumulate – and that is what interested the team at Georgia Tech.
“Drones and other autonomous rovers, including our machines on Mars, are susceptible to failure because of the accumulation of airborne particles,” explains associate professor Dr David Hu. “Understanding how biological systems prevent soiling could help inspire low-energy solutions for keeping sensitive equipment free from dust and dirt.”
All throughout nature, animals have developed incredible ways to handle their housekeeping – strategies that we can learn from. Even the sea otter, whose fir is among the densest in the animal kingdom at a whopping 850,000-1,000,000 hairs per square inch, manages to do it.
“A sea otter has the surface area of a professional hockey rink,” says Hu. “But in order to understand how animals keep clean, one must first understand how they get dirty.” The team not only managed to calculate the “true surface area” (every location dirt can collect) for 27 mammals and insects, but also combined that data with past research on each animal’s dirt-defenses. Bees, for example, rely on bristles to keep pollen off their eyes, while fruit flies use built-in catapults to fling dust from their bodies with an acceleration 500 times that of Earth’s gravity.
The next step is to determine which of these strategies could be efficient at our mammoth scale. “An animal gets clean for free if it has the right kind of surface,” writes the team. “If we have this mindset, perhaps we can design new devices that get clean for free too.” Imagine a world where sensors, lenses, wires – even vehicles couldn’t get dirty.
“Consider solar panels. Like the eye, they must let light in. But solar panels lose 7% of their power annually due to dust accumulation. The most high-tech solution is the squeegee. When you think about it, the computer age has put us light years ahead of our ancestors in terms of communication, but our cleaning methods remain stuck in the past. Indeed, the future may be looking rather hairy.”
IMAGES: Georgia Tech, Rob Ketcherside/Flickr