Researchers from North Carolina State University have developed miniature soft hydraulic actuators that can control the deformation and motion of thin soft robots. They have demonstrated that this technique works with shape memory materials, allowing users to lock the soft robots into a desired shape and return them to their original shape as needed. This approach utilizes commercial multi-material 3D printing technologies and shape memory polymers to create soft actuators on a microscale, enabling exceptional control and delicacy in controlling small soft robots, which are only 0.8 millimeters thick.
The new technique involves creating soft robots with two layers: a flexible polymer layer with microfluidic channels and a flexible shape memory polymer layer. By pumping fluid into the microfluidic channels, hydraulic pressure is generated to move and change the shape of the soft robot. The pattern of microfluidic channels controls the motion and shape change of the soft robot, such as bending or twisting. The amount and rate of fluid introduction determine how quickly the soft robot moves and the force it exerts. To freeze the soft robot’s shape, users can apply heat and then cool the robot, preventing it from reverting to its original shape after the fluid is removed.
Fine-tuning the thickness of the shape memory layer relative to the layer with microfluidic channels is crucial for the success of this technique. The shape memory layer needs to be thin enough to bend under pressure but thick enough to retain the soft robot’s shape after the pressure is removed. The researchers demonstrated the technique by creating a soft robot gripper capable of picking up small objects. By applying hydraulic pressure and then heat, the gripper could be fixed in a closed position, allowing the transportation of objects. The gripper could then be released by applying heat again, showcasing the potential applications of miniature soft actuators in small-scale soft robots, shape-shifting machines, and biomedical engineering.
The researchers emphasize the quick and efficient operation of the soft robots, which can be heated up to 64C using an infrared light source and cool rapidly. They have also demonstrated a gripper inspired by vine-like structures in nature that wraps around objects and clasps them tightly for a secure grip. This work serves as a proof-of-concept for the new technique and highlights the potential applications of miniature soft actuators in various fields. The study was supported by the National Science Foundation under grants 2126072 and 2329674, showcasing the importance of funding in advancing innovative research in soft robotics and shape memory materials.
In conclusion, the development of miniature soft hydraulic actuators for controlling the motion and deformation of thin soft robots opens up new possibilities in the field of soft robotics. The use of 3D printing technologies and shape memory polymers allows for precise control and delicacy in manipulating small soft robots. By utilizing microfluidic channels to generate hydraulic pressure, users can control the motion and shape change of the soft robots, freezing their shape when needed and returning them to their original form. This innovative technique has the potential for applications in small-scale soft robots, shape-shifting machines, and biomedical engineering, showcasing the versatility and adaptability of miniature soft actuators in various fields.