MXene based actuators – Breakthrough in artificial muscle technology

In robotics, an actuator is the robotic equivalent of a muscle that can move. The actuator uses a stimulus like electricity to expand, contract, or rotate like muscle fibers. Robotics engineers in the world are striving to build more dynamic actuators that can react quickly, bend without breaking, and are very durable, as soft robotic muscles can have a wide range of robotic applications, from wearables to advanced prosthetics.

A team of researchers from the Creative Research Initiative Center for Functionally Antagonistic Nano-Engineering at KAIST (Korea Advanced Institute of Science and Technology) has developed an ultra-thin, responsive, flexible and durable artificial muscle using a specific type of compound called MXene that has layers only a few thick atoms.

The actuator that looks like a skinny strip of paper about an inch long, can respond very quickly to low voltage and is continuously moving for more than five hours. Recently reported in the journal ‘Science Robotics,’ the achievement was demonstrated on a kinetic art piece with a robotic blooming flower brooch, robotic butterflies dancing, and tree leaves fluttering. They also designed robotic butterflies that move up and down their wings, fluttering the leaves of a tree sculpture.

MXene (T3C2Tx) consists of thin titanium and carbon compound layers. It was not flexible on its own; when bent in a loop, sheets of material would flake off the actuator. That changed when the MXene was connected to a synthetic polymer “ionically cross-linked” — through an ionic bond. A combination of materials made the actuator flexible while maintaining the strength and conductivity that is critical for electricity-driven movements.

“Wearable robotics and kinetic art show how robotic muscles can have fun applications. It indicates the enormous potential for small, artificial muscles for a variety of uses, such as haptic feedback systems and active biomedical devices,” said Il-Kwon Oh. Oh is the lead author of the paper and mechanical engineering professor. Next, the team plans to investigate more practical applications of soft actuators based on MXene and other MXene 2D nanomaterials engineering applications.