New soft gripper offers unprecedented combination of strength and delicacy

Researchers from North Carolina State University have created an innovative robotic gripping device capable of delicate handling, strong lifting, precise manipulation, and dexterity in folding cloth. This unique gripper can pick up a drop of water and a weight of 6.4 kilograms, while also being able to handle microfilms 20 times thinner than a human hair.

The team integrated advanced technology, allowing the gripper to be controlled by electrical signals from forearm muscles, showcasing its potential for use in robotic prosthetics. This achievement addresses the challenge of balancing strength, precision, and gentleness in a single soft gripper, which is vital for handling various objects.

The design is an evolution of flexible, robotic grippers inspired by the art of kirigami, which involves cutting and folding two-dimensional materials to create three-dimensional shapes. With its impressive capabilities, this device holds promise not only in manufacturing applications but also in the field of robotic prosthetics.

Credit: North Carolina State University

According to Yaoye Hong, one of the co-authors and a recent Ph.D. graduate from NC State, the new grippers use kirigami too, but they have undergone significant improvements compared to the previous design. They have optimized the fundamental structure and the approach trajectory, enhancing their strength and gentleness when handling objects.

The key to achieving remarkable strength and gentleness lies in the gripper’s force distribution throughout its structure. Jie Yin explains that the strength of robotic grippers is usually measured by the payload-to-weight ratio. Surpassing the previous record by 2.5 times, their grippers, weighing only 0.4 grams, can lift an impressive 6.4 kilograms, resulting in a payload-to-weight ratio of about 16,000. This exceptional combination of strength, precision, and gentleness opens up a wide range of potential applications for the new grippers.

Robotic grippers can turn book pages. Credit: Jie Yin

The new technology’s appealing features are primarily derived from its innovative structural design, rather than the materials used to make the grippers. Yaoye Hong mentions that the grippers can be fabricated from biodegradable materials like sturdy plant leaves, making them ideal for limited-use applications, such as handling food or biomedical materials, including sharp medical waste like needles.

The researchers successfully integrated the gripping device with a myoelectric prosthetic hand, providing enhanced functionality for tasks that were challenging for existing prosthetic devices. Although the new gripper cannot replace all functions of current prosthetic hands, it can complement them without the need to replace or modify existing motors.

In their proof-of-concept testing, the kirigami grippers worked well with the myoelectric prosthesis, allowing them to turn book pages and pluck grapes from vines. The researchers envision broad applications for the gripper design, ranging from robotic prosthetics and food processing to pharmaceutical and electronics manufacturing, and they are eager to collaborate with industry partners to put the technology into practical use.

The research paper, titled “Angle-programmed tendril-like trajectories enable a multifunctional gripper with ultradelicacy, ultrastrength, and ultraprecision,” has been published in the journal Nature Communications.

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