Soft Robotics Breaks Out of Its Cocoon

Soft robots have emerged as a new frontier in robotics technology, offering exciting possibilities for a wide range of applications. These robots are made of materials that are flexible, stretchy, and can deform easily. As a result, they can move in ways that traditional robots cannot, making them ideal for tasks that require a high degree of dexterity and adaptability. These traits make soft robots well suited for applications in many fields, including medicine, manufacturing, and search and rescue.

Many soft robots are modeled after creatures found in the natural world, which have soft bodies that allow them to move in unique ways. For example, a soft robot inspired by an octopus might have tentacles that can bend and stretch in all directions, allowing it to grip objects in a variety of ways. Similarly, a robot inspired by a jellyfish might have a bell-shaped body that can contract and expand, allowing it to swim through water in a fluid motion.

Developing versatile soft actuators that can move in more than one direction has proved to be very challenging, however, which has made it difficult to bring these robots to life as they are imagined. A new solution to this problem has just been developed by a team of engineers at North Carolina State University, which may make certain types of soft robots easier to build in the future. Taking inspiration from the caterpillar, they have created a soft actuator that can stretch and bend in two directions.

The actuator is made of layers of a liquid crystal elastomer (LCE) with a pattern of silver nanowires embedded within them. The LCE reversibly and predictably deforms when it is heated up, and the nanowires can provide that heat via an electrical current. The top layer contracts when heated, while the bottom later expands, which enables actuation in multiple directions. The movements can be controlled with precision by applying a current only where movement is desired. And by applying more or less current, the magnitude of the reaction can be adjusted.

Using this method, the team created a caterpillar-like robot that is little more than a strip of the actuator and some wires leading to an external device that sends the control signals. This robot was demonstrated switching between pushing and pulling itself forward to allow it to fit underneath a low barrier. It then turned back and went the other way, showing the caterpillar’s ability to move in a second direction.

While the speed of the caterpillar can be controlled by changing the level of electrical current that is supplied, there are limits. This is because the polymer needs time to cool so that it can fully relax before the next contraction or expansion. Trying to move any faster than this heating-cooling cycle allows would impair movement, which effectively puts a speed limit on any devices that implement this actuation mechanism.

The researchers are presently at work integrating their soft actuator with sensors and other technologies to understand what application areas may benefit the most from it. They have their eyes on search and rescue devices as a first target. Full details of the team’s methods are available in the recently published paper in Science Advances.