spaceSpace and Physics

Robotic Arm Uses Ultrasonic Levitation To Grip Objects

The phenomenon of ultrasonic levitation allows objects to be suspended by acoustic waves. Stefan Weiss/ ETH Zürich

A Swiss researcher is developing a “no-touch” robotic gripper that uses sound waves to “trap” objects, causing them to levitate. Marcel Schuck, a Pioneer Fellow at ETH Zürich, has unveiled his prototype robot arm, which can lift and manipulate small objects without the need for human touch. This technology would prove particularly useful in the watchmaking, micromechanics and semiconductor industries, where the handling of small, fragile parts is required.

At the heart of the design is the phenomenon known as acoustic levitation. The two 3D-printed semi-spheres are fitted with lots of small loudspeakers that emit ultrasonic waves. These sound waves have a frequency over 20kHz, outside of a human’s hearing range.

Numerous loudspeakers are placed in the semi-spheres which emit the ultrasound waves. Stefan Weiss/ ETH Zürich

As these acoustic waves cross paths between the semi-spheres they interfere with each other and if the conditions are right they produce a standing wave. Along the standing wave are points of high pressure and low pressure in which an object can be trapped within.

The size and mass of the object being levitated is restricted by the properties of the sound wave, such as its frequency and the strength of the pressure field it generates.

Although this effect has been understood and utilized for over 80 years, Schuck’s project, No-Touch Robotics, hopes to further its uses.

Alongside the physical equipment, Schuck and his team are also developing some software that would allow the user to manipulate the position of the pressure points between the speakers. Their hope is that the suspended object would then be able to be repositioned without falling to the ground. This is in addition to the maneuvers that the robot arm can perform.


For certain fields this technology could also provide economic benefit. Conventional robots are prone to damaging objects, which is countered by attaching rubber-like grippers. However, not only do these lead to contamination, but a different gripper is required for almost every shape, which is expensive to maintain. Using Schuck’s equipment and associated software would alleviate these problems.

Schuck hopes this technology will be useful when handling small fragile objects. Stefan Weiss/ ETH Zürich

“The main aim is to explore the potential fields of application and open doors within industry,” Schuck said in a press release. He is currently putting together a “development kit” for potential clients that includes a robot gripper, control software and instructions. If all goes well the technology could be used outside of the lab by 2021.


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