Researchers print functional artificial muscles with 3D printer

A team of scientists at the Swiss Federal Laboratories for Materials Science and Technology (Empa) has succeeded in creating artificial muscles using 3D printing. The researchers hope that in the future it will be possible to produce an entire artificial heart using a similar process.

Artificial muscles can be used not only in robots, but also in medicine to replace injured muscle tissue, for example. However, developing artificial muscles that have the same properties as their natural counterparts is a major challenge, the Empa researchers write in the study “Rapid Manufacturing of High-Permittivity Dielectric Elastomer Actuator Fibers”, which has been published in Advanced Materials Technologies. This is because they have to be just as powerful, elastic and soft as biological muscles.

The Swiss researchers have now developed dielectric elastomer actuators (DEA) that consist of two different silicone-based materials and can be printed in one go using a 3D printer. The artificial muscles consist of a conductive and a non-conductive dielectric that lie on top of each other in layers. When an electrical voltage is applied to the electrodes, the actuator contracts; when the voltage is switched off, it returns to its original position.

Development of special printable materials

Printing such an artificial muscle is a difficult task, says Empa scientist Patrick Danner. The two soft materials have different properties, but must not mix during the printing process. Nevertheless, they must be firmly bonded together afterward to function as an artificial muscle. At the same time, both materials must remain soft enough to react to the electrical impulses as desired.

The two materials must also liquefy as much as possible under heat so that they can be extruded together through the printer nozzle in a 3D printer. Immediately afterward, however, they must become so viscous that they do not run but retain their shape.

“These properties are often in direct contradiction to each other,” says Danner. “If you optimize one of them, three others – usually change for the worse.”

However, in cooperation with scientists from the Swiss Federal Institute of Technology in Zurich (ETH Zurich), the Empa researchers have managed to combine the different properties. In addition, the printer nozzle had to be specially adapted to be able to print the materials.

Areas of application for artificial muscles

As a first step, the researchers want to use the artificial muscles to develop a type of force feedback glove. The glove should enable the wearer to receive feedback in virtual worlds when touching virtual objects.

However, the researchers believe that their actuators are suitable for various other applications, such as in cars, machines, and robotics. There they could replace electric servomotors, for example.

Medical applications are also conceivable. This is because their printing process allows the artificial muscles to be precisely shaped and even long elastic fibers to be printed. The researchers now hope to be able to make the artificial muscles even thinner to make their function similar to that of real muscle fibers. In the future, according to the scientists, it could also be possible to print a complete artificial heart.

(olb)