Doraemon’s fingerless hands are one of the little mysteries that almost everyone who has read the manga has wondered about at some point.
Created by Fujiko F. Fujio, Doraemon is a beloved manga series that has entertained generations of readers around the world. The story follows a robotic cat from the 22nd century who travels back in time to help Nobita, a clumsy and often unlucky boy. Doraemon’s most iconic feature is the magical pocket on his belly, from which he can pull out all kinds of extraordinary gadgets.
There is one detail that might go unnoticed at first but becomes surprisingly puzzling upon closer inspection. Doraemon’s hands are simply two small white spheres, with no fingers or fingerprints. Yet the robotic cat can reach into his pocket to retrieve gadgets, happily grab and eat dorayaki, and even hold a pen.
Those round hands also lead to some hilarious situations. Whenever Doraemon plays rock-paper-scissors with Nobita, for example, he can only make a fist. In other words, his hands cannot open up or form the shape of scissors. And yet, when necessary, Doraemon somehow manages to perform all sorts of delicate tasks.
Interestingly, real-world engineers have asked exactly the same question and attempted to find an answer. A research team led by Associate Professor Kenjiro Tadakuma at Tohoku University in Japan developed a soft robotic hand that Japanese media playfully nicknamed the “Doraemon hand.” From the outside, it looks like nothing more than a smooth, rounded shape without any fingers.
The secret lies in a rubber membrane filled with ground coffee particles. When the hand is not holding anything, the particles behave loosely, allowing the structure to deform and conform closely to the object it needs to grasp. Once the air is sucked out, however, the particles become tightly packed, stiffening into a solid-like structure that can hold the object firmly. This phenomenon is known as the jamming transition, and it can be achieved using familiar materials such as coffee grounds or even uncooked rice.
The research team’s results are particularly impressive. The hand can deform under a force of just around 3 newtons. Once it has gripped an object, however, it can withstand a force of 30 newtons without changing shape. This means its stiffness can increase by more than tenfold. In experiments, the robotic hand successfully lifted an object weighing 1.3 kilograms and even pressed a button on an electrical control cabinet. The technology could prove useful in disaster rescue operations, where operators cannot predict in advance what kinds of objects a robot will need to handle.
Of course, Doraemon comes from the 22nd century, so nobody expects his magical gadgets to work through coffee grounds. Still, the idea of a perfectly round hand capable of gripping all kinds of objects no longer seems entirely far-fetched. Perhaps, a few years from now, real-world robots will actually have hands just like Doraemon’s!
Sources: gamek