Muscles from the 3D printer

Swiss researchers have succeeded in printing artificial muscles out of silicone. In the future, the technology could be used not only in medicine, but also in robotics.

Developing artificial muscles that can keep up with the real ones is a major technical challenge, explains the Swiss Federal Laboratories for Materials Science and Technology (Empa). These must not only be strong, but also elastic and soft.

Now, for the first time, the researchers have developed a method to produce such complex components with the 3D printer. The printed so-called dielectric elastic actuators consist of two different silicone-based materials: a conductive electrode material and a non-conductive dielectric.

Compressed muscles must be as soft as possible

These materials interlock in layers. “It’s like interlacing your fingers,” explains Empa researcher Patrick Danner. If an electrical voltage is applied to the electrodes, the actuator contracts like a muscle. If you switch it off again, it relaxes again.

However, the production is not an easy undertaking. This is because the printed “muscles” must be as soft as possible so that an electrical stimulus can lead to the required deformation. In order to be able to produce something with the 3D printer, certain criteria must also be met: The materials must liquefy under pressure so that they can be pressed out of the printer nozzle. Immediately afterwards, however, they must be viscous enough again to retain the printed form. “These characteristics are often in direct contradiction to each other,” says Danner. “If you optimise one of them, three others change, usually to the detriment.”

In the future, you could print a whole heart like this

In collaboration with researchers at ETH Zurich, Danner and Dorina Opris, head of the research group, have succeeded in reconciling many of these contradictory characteristics.

With the process they have newly developed, not only complex shapes can be printed, but also long elastic fibers. “If we make them a little thinner, we come quite close to how real muscle fibers work,” says Opris. In the future, it may even be possible to print an entire heart from such fibers, the researcher believes.