Researchers recently developed a new design using thermal actuation to create rapid movement in soft robotic devices.
A ScienceDaily report specified according to the paper's corresponding author Yong Zhu and distinguished professor Andrew Adams from Mechanical and Aerospace Engineering at NC State, using thermal actuation "is not new for soft robots," although the most challenging part for soft thermal actuators was that they were somewhat unhurried, and these scientists at North Carolina State University have transformed them to become fast.
Essentially, actuators are the parts of a device such as a space robot that generate motion by converting energy into work.
The paper's first author Shuang Wu, a Ph.D. student at NC State, said that making the new actuator design work is a structure with a bi-stable design.
He also said, "Think of a snap hair clip," describing it as "stable" until one applies a specific amount of energy by bending it over and then snaps into a different form or shape, which is stable, as well.
Bi-Stable Thermal Actuator
In this circumstance of the new thermal actuator, researchers of the study published in Soft Robotics describe it as "bi-stable," although which form the material prefers is dictated by temperature.
Here's how the system works. The study authors layered two materials on top of each other, with silver nanowires at the center.
The said two materials have a dissimilar coefficient of thermal expansion. Meaning they are expanding at different rates as they heat up. Practically, it means the structure is bending when it is heated.
Such a layered material is then molded into a design that provides a default curving in one direction bending downward.
Essentially, when voltage is applied to the silver nanowires, the materials get heated up, making them bend in the opposite direction.
Once a certain temperature is reached, the critical temperature, the material is snapping into its new default shape, swiftly curving up, a similar NC State University report said.
Meanwhile, when the voltage is taken out, the temperature goes back down. In addition, it's cooling past another critical temperature; the material is snapping back to its past default shape, curving down quickly.
2 Critical Temperatures
Notably, the two critical temperatures are different. The first one, in particular, is higher. Through the application of current to the nanowires in a standard pattern, the material can be made snapping back and forth.
To demonstrate such an approach, the study authors developed two prototypes. One of them simulates a Venus flytrap's snapping behavior, while the other is a "crawler" that's capable of moving more than a single body length a second.
According to Zhu, potential applications range from "biomedical applications to prosthetic devices to high-end manufacturing."
Moreover, any application in which one would intend to be able to move quickly but want to avoid rigid materials and conventional robotics.
Succeeding steps include the development of sensors and regulation of mechanisms that could more completely automate the actuation process, enabling it to operate more efficiently than purely manual regulators.
Describing their paper, Zhu explained they are also interested in exploring other possible materials so that they could fine-tune the thermal as well as the mechanical properties. This could enable them to tailor both the speed and force of the actuator.
Related information about actuators for soft robotic devices is shown on Riddick Li's YouTube video below:
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