Listen to this piano-playing robot hit all the right notes

Robots are smarter, stronger, and more complex than ever before, but they still stumble over nuanced motions that most humans take for granted, like adjusting finger pressure and speed to overcome a sticky keyboard or a lagging smartphone screen. To make these subtle adjustments, our brains interpret cues from the environment, and our finely tuned bodies modify our movements.

Taking a page from nature, researchers used 3D printing to integrate polymers of different stiffness into several soft, skeletonlike robotic hands. By creating the robot out of elastic materials, the scientists eliminated the need for motors or actuators at every joint, saving power and simplifying the design.

The scientists then mounted the skeleton hands on a robotic arm and had them play piano music in several different styles—from bouncy staccato notes to smooth glissando slides, which require the hand to stretch across an entire octave. The entire time, the robot used only its arm motor to drive the movements.

When researchers used sensors on the keyboard to track the timing and force of the robot hand, they found a close match to the movements of humans playing the same pieces of music. Compared with stiff-fingered robots, whose note hitting tends to be more precise but lacks style, the new robots were capable of more complex musical phrasing, they report today in Science Robotics.

The new hands might one day have touch sensors that can help the robot in tasks that require a delicate touch, like picking fruit or feeling for tumors. For humans, they could even be used to create more lifelike prosthetics. But for now, they’re more likely to strike a festive note at your holiday party.