Engineers have used nanostructured fibres to impersonate human muscles. 

Researchers around the world are looking for ways to mimic the human body, specifically the actuators that control muscle movement.

This quest has led to many innovations to improve robotics, prosthetic limbs and more, but creating these actuators typically involves complex processes, with expensive and hard-to-find materials.

But now, researchers in the US have created a new type of fibre that can perform like a muscle actuator, better than other options that exist today, using muscle-like fibres that are simple to make and recycle.

“You can basically build a limb from these fibres in a robot that responds to stimuli and returns power, instead of using a mechanical motor to do this, and that’s good because then it will have a softer touch,” says Dr Manish Kumar from the Cockrell School of Engineering.

This kind of robotic arm could be used in an assistive exoskeleton to help people with weak arms regain movement and strength. 

Another potential application, the researchers say, could be a sort of ‘self-closing bandage’ that could be used in surgical procedures and naturally degrade inside the body once the wound heals.

“Actuators are any material that will change or deform under any external stimuli, like parts of a machine that will contract, bend, or expand,” says researcher Dr Robert Hickey. 

“And for technologies like robotics, we need to develop soft, lightweight versions of these materials that can basically act as artificial muscles. Our work is really about finding a new way to do this.”

The fibre material is known as a block co-polymer. Creating it only requires putting the polymer in a solvent and then adding water. 

One part of the polymer is hydrophilic (attracted to water), while the other part is hydrophobic (resistant to water). 

The hydrophobic parts of the polymer group together to shield themselves from the water, creating the structure of the fibre.

Similar existing fibres require an electric current to stimulate the reactions that bond parts together. This chemical cross-linking is harder to make happen, compared to the researchers' new fibre, which is a mechanical reaction, meaning the parts take care of most of the work themselves. 

Another added bonus is it is simple to reverse the process and return the pieces of the fibre to their original states.

“The ease of making these fibres from the polymer and their recyclability are very important, and it's an aspect that much of the other complicated artificial muscle research doesn't cover,” Dr Kumar said.

The researchers found their fibres were 75 per cent more efficient in terms of converting energy to movement, able to handle 80 per cent more strain and could rotate with more speed and force than current actuators. It can stretch to more than 900 per cent of its length before it breaks.

More details are accessible here.