Mimicking DNA superhelix, robots drive mechanically more efficiently

Scientists at the University of Wollongong (UOW) have developed a new type of artificial muscle inspired by DNA superhelix for use in miniature robots.

Miniature artificial muscles could be used to create advanced prosthetic limbs and wearable devices to help injured or physically disabled people move. In addition, it can also be used for non-invasive surgical tools and industrial micro-manipulators.

The title of the paper is "Dual High-Stroke and High-Work Capacity Artificial Inspired by DNA Superhelix" Supercoiling) ".

Paper link:

https://robotics.sciencemag.org/content/6/53/eabf4788

1. One million periodic movements provide strong kinetic energy for the micro-robot
The main technical challenge for microbots is how to generate powerful movement and force on small devices, and artificial muscles can solve this problem.

Professor Geoffrey Spinks, from UOW's Institute of Innovative Materials Australia and lead author of the study, said: 'It is tempting to power tiny robots using driving materials that mimic skeletal muscle, but they are too complex to be easily downsized. So we are looking to artificial muscles to provide good mechanical drive for the robot."

Artificial muscles support large movements and are easy to recover, and machines work efficiently and can last millions of cycles, making them ideal for tiny machines, says Professor Spinks.

Second, inspiration from DNA, super spiral contraction freely

"Our new artificial muscle mimics the way DNA molecules contract into the nucleus," said Professor Spinks.
DNA is one of the hardest and longest natural polymers, and to enter a micron-sized nucleus, the centimeter-sized DNA must shrink by more than a thousand times, shrinking in size through a super-helical process.

"We were able to create a DNA-like twine by expanding the twisted fibers. A superhelix occurs when the ends of the fibers become blocked by rotation. Under the superhelix, the artificial muscles generate a lot of mechanical energy."
The research team optimized the fiber through modeling, reducing the size of the fiber to reduce its response time, thereby maximizing the rate and energy output.
They then successfully applied these new muscles to possible applications, including tiny scissors and tiny tweezers.

3. After the reaction speed is improved, the application scenarios of artificial muscle are richer
Dr Sina Naficy, one of the co-authors, who works at the University of Sydney, said: "Mimicking behaviour in nature is very interesting. We have learned that the fibers that form fibrous composites are wound into helices that provide a convenient way to store and release mechanical energy. There are many such helical complexes in nature, from DNA molecules to plant tendrils. These systems offer exciting prospects for future development."

Dr Javad Foroughi, of UOW's School of Engineering and Information Sciences and another co-author of the paper, said: "The new artificial muscle works rather slowly, limiting the scenarios in which it can be used, so our next goal is to speed up the response." The research team has used hydrogels to drive volume changes in the superhelix.

▲ The process of superhelix removal in polyester-polyamide composite fibers

Professor Spinks said: "We do believe that making fibers with a smaller diameter could improve speed, but for now, this application is limited to those fibers that require a slower response." "The development of faster superhelical muscles will open up further application areas. We hope that others will explore different ways to generate volume changes, such as through electrical heating leading to faster responses."

Conclusion: The application of new artificial muscle is more extensive
Artificial muscles inspired by DNA superhelix are highly flexible and behave very similar to real muscle fibres, which is of great significance not only for medicine but also for the development of robotics.

With the continuous research and development of special polymer materials and intelligent materials, artificial muscles will be more flexible in stretching, bending, twisting, contracting and other states, and will play a greater role in medicine, robotics and other fields.