Complexity on a small scale: A 3D-printed soft actuator or "artificial muscle." Credit: Empa.
Researchers at Empa are developing artificial muscles that could one day move like real ones.
Using advanced 3D printing, they have created soft and elastic structures that contract and relax with electricity, just like human muscles.
Their findings were recently published in [_Advanced Materials Technologies_.](https://doi.org/10.1002/admt.202500190)
**Why artificial muscles matter**
Artificial muscles could revolutionize medicine, robotics, and everyday life. They might help people with mobility issues, assist workers with heavy lifting, or even replace damaged muscle tissue.
However, creating artificial muscles that truly match human muscles in flexibility, softness, and strength has been a major challenge.
Muscles in our body move because of electrical impulses. To replicate this, scientists use actuators—devices that turn electrical signals into movement. Actuators are already used in many machines, from car engines to industrial robots, but these mechanical parts are typically rigid and nothing like real muscles.
**The Breakthrough: 3D-printed soft actuators**
A team at Empa’s Laboratory for Functional Polymers has found a way to 3D print artificial muscles using soft materials.
Their design is based on **dielectric elastic actuators (DEA)**, which are made of two silicone-based materials: one that conducts electricity and one that does not. These materials are arranged in layers, much like interlaced fingers. When voltage is applied, the actuator contracts like a muscle; when the voltage is turned off, it relaxes back to its original shape.
3D printing such a structure is tricky because both materials must behave similarly when printed but remain separate in the final product. The muscles must also be as soft as possible to react efficiently to electrical signals.
Additionally, the materials need to be fluid enough to be extruded from the printer but solid enough to hold their shape immediately after printing. Balancing these properties is difficult, as improving one often worsens another.
**From VR gloves to medical applications**
To overcome these challenges, Empa researchers worked with scientists from ETH Zurich. Together, they developed two special inks that can be used to print functional soft actuators. This collaboration is part of the _Manufhaptics_ project, which aims to create a glove that allows users to “feel” virtual objects by using artificial muscles to create resistance.
But the potential goes beyond VR. These lightweight, silent actuators could replace traditional mechanical parts in cars, robots, and machinery. In the medical field, they might eventually be used to create artificial organs.
Researchers Opris and Danner are already working on refining their technique to print long, thin elastic fibers that behave even more like real muscle fibers. Their ultimate dream? To print a fully functional artificial heart.
While there’s still a long way to go, this breakthrough brings us one step closer to creating artificial muscles that truly mimic the power and flexibility of real ones.