This 3D printed gripper doesn’t need electronics to function

The device was developed by a team of roboticists at the University of California San Diego, in collaboration with researchers at the BASF corporation, who detailed their work in a recent issue of Science Robotics.

In their endeavour, the researchers aimed to create a soft gripper, capable of immediate use upon 3D printing, featuring integrated gravity and touch sensors. Consequently, this gripper possesses the unique ability to effortlessly grasp, hold, and release objects, marking the first of its kind in existence.

“We designed functions so that a series of valves would allow the gripper to both grip on contact and release at the right time,” said Yichen Zhai, a postdoctoral researcher in the Bioinspired Robotics and Design Lab at the University of California San Diego and the leading author of the paper, which was published in the June 21 issue of Science Robotics. “It’s the first time such a gripper can both grip and release. All you have to do is turn the gripper horizontally. This triggers a change in the airflow in the valves, making the two fingers of the gripper release.”

Through fluidic logic, the robot gains the ability to retain the memory of its grasp on an object. When it senses the lateral force exerted by the object during its rotation towards a horizontal position, it intuitively releases the grip, ensuring a seamless and efficient handling process.

Soft robotics offers the exciting potential for robots to interact safely with humans and delicate items. This gripper can be seamlessly integrated onto a robotic arm, making it ideal for a wide range of applications in industrial manufacturing, food production (such as handling fruits and vegetables), as well as research and exploration tasks.

One of its key advantages is its versatility, as it can operate untethered, relying solely on a bottle of high-pressure gas as its power source. This feature grants the gripper greater mobility and adaptability, enhancing its usefulness in various scenarios and environments.

The majority of 3D printed soft robots commonly exhibit a degree of stiffness, which can limit their flexibility and adaptability. Additionally, they often suffer from numerous leaks once they are produced, causing functional issues, and reducing their overall effectiveness. Furthermore, extensive post-printing processing and assembly are typically required to render these soft robots usable, adding complexity and time to the manufacturing process.

The team successfully surmounted these challenges by devising a novel 3D printing technique. In this method, the printer nozzle follows an uninterrupted trajectory throughout the entire pattern of each printed layer. This approach eliminates the issues of stiffness and leaks, resulting in soft robots that are more functional and reliable right after being printed, requiring minimal post-processing and assembly.

“It’s like drawing a picture without ever lifting the pencil off the page,” said Michael T. Tolley, the senior author on the paper and an associate professor in the UC San Diego Jacobs School of Engineering.

Indeed, the newly developed 3D printing method significantly decreases the probability of leaks and defects in the printed soft robots.

The new 3D printing method brings another significant advantage by enabling the production of thin walls with a remarkable thickness of as little as 0.5 millimetres. This breakthrough allows for the creation of complex and curved shapes that promote a broader range of deformation, ultimately leading to a softer and more flexible overall structure.

To achieve this, the researchers drew inspiration from Eulerian paths in graph theory, where a path touches every edge of a graph exactly once without repetition. By applying this concept to the printer nozzle's trajectory, they were able to attain the desired level of precision and intricacy in the printed patterns, allowing for the construction of intricately designed and highly deformable soft robotic components.

“When we followed these rules, we were able to consistently print functional pneumatic soft robots with embedded control circuits,” said Tolley.