These Super-Thin Flexible Actuators Are Perfect for Soft Robotics

When you’re building a conventional robot and want it to move, you just attach some sort of motorized actuator, like a stepper motor, servo motor, or linear actuator. But that approach doesn’t work in soft robotics, because there is no rigid frame for the motor to attach to. That’s why soft robots often utilize hydraulics or pneumatics to fill bladders in order to facilitate movement. Unfortunately, that technique requires bulky, noisy pumps and a lot of power. These new super-thin and flexible actuators, however, only require a bit of voltage to move.

This actuation technology was developed by researchers from the Korea Advanced Institute of Science and Technology (KAIST). Unlike typical actuators, which usually rely on rigid spinning motors, these are integrated directly into a thin, flexible film. They are able to contract when a low voltage is applied to the film thanks to a special material called MXene that is made up of layers of titanium and carbon compounds. By itself, that material is brittle. But when it’s applied to a thin sheet of synthetic polymer via an ionic bond, the film can flex and then return back to its original shape repeatedly.

To demonstrate this technology, the researchers created a handful of kinetic art pieces. One is a group of artificial butterflies perched on a branch that flutter their wings when voltage is applied to the actuators. Another is a tree full of dancing leaves. The last one, which is designed to illustrate how these actuators are suitable for wearable devices, is a flower with pedals that open up in bloom. While those are all artistic uses of the actuators, that doesn’t mean that’s all the technology is good for. The same principles can be applied to help all kinds of soft robots move.