A basic hairbrush looks essentially the same as it did in the 1600s, and combs look nearly identical to archaeological finds from 8000 B.C. But next-generation hair grooming tools might take inspiration from an unlikely source: cats.
When researcher Alexis Noel saw her cat lick a microfiber blanket–and had to help him get his tongue unstuck–she started thinking about the unusual structure of cat tongues. The tongue is covered in tiny, hard spines that lift and rotate to detangle fur.
Noel, a doctoral student in mechanical engineering at Georgia Tech, works in a lab with high-speed cameras that can capture the mechanics as cats lick their fur. Using the footage, the researchers were able to study the “spines” on the tongue.
“They’re kind of like little Velcro hooks,” Noel says. “They actually look just like cat claws, or if you look at claws from any mammal species, they look exactly the same, but in miniaturized form. These rigid claws are about the same stiffness as fingernails, and they’re embedded in the soft tissue of the cat tongue.”
As cats groom their fur–something they do in as much as 50% of their waking hours every day–they stiffen some of the muscles in the tongue, and the spines pop up, rotating as they run into tangles. “Because of their unique, sharp, curved nature, they can actually penetrate tangles and pierce these tangles and tease them apart,” she says.
It’s something that a normal hairbrush can’t do. The tongue is also self-cleaning. While a regular brush collects mats of hard-to-clean hair at the bottom, hair slips off a cat tongue quickly as soon as the spines flatten. On a human hairbrush with a similar design, you could push off hair with a single finger.
The researchers used the footage, and CT scans of a tongue, to 3D-print a model of the spines, embedding them in a tongue-like silicon substrate. With the model, they can test how the tongue works in more detail.
“You can recreate what’s actually happening on the surface of the cat tongue and precisely change variables,” says Noel. “That way we’re not dependent on a cat. You can’t exactly tell a cat to do something. It does whatever it wants to do.”
Using the model, the team is beginning to work on practical applications of the design–from better hairbrushes and carpet cleaning techniques to new features for soft robotics.
“Let’s say a robot needs to grab the surface of a rock,” she says. “These spines will allow the robot to grab into those crevices and pull with significant force.”
The design could also potentially help with wound cleaning, something that cats also do while grooming.
No one has studied the physics of cat tongues in this detail before. “Everybody knows that a cat’s tongue is rough,” says Noel. “But no one’s really looked at how the structure on the surface of the tongue works, what makes it so rough, and what makes it so efficient.”
The researchers are filing for a patent, and plan to create new products based on the design.
[Poster Photo: Flickr user Trish Hamme]