Terminator half human creatures, half robots with spider silk "muscles"

Terminator-style humanoid robots could become a reality thanks to "artificial muscles" made from spider silk.

According to scientists, the miracle material, stronger than steel and more elastic than rubber, can be exploited for energy purposes.

And robots equipped with this new fabric would be released to move like humans, allowing them to better grasp and pick up objects.

The plan is to eventually get them to help in a range of tasks – ranging from non-invasive surgeries to helping in nursing homes.

According to new research, the material requires the right amount of moisture and above a certain level of relative humidity in the air, they contract and turn around abruptly.

This exerts enough force for them to function as actuators, devices that move to perform tasks such as controlling a valve.

Known as "supercontraction", the thin bands shrink as a result of changes in the atmosphere.

What's more, they also have an amazing ability to twist at the same time, which gives them significant torsional strength.

The effect reported in Science Advances is similar to the action of the muscles – offering the hope of ultra-powerful machines for manufacturing or gentle robots to take care of the elderly.

It could also result in smart clothing, also known as electronic textiles, that allows computers and electronics to integrate – and green generators.

Professor Markus Buehler, Head of the Department of Civil and Environmental Engineering at the Massachusetts Institute of Technology, said: "This is a new phenomenon."

Spider silk is harder than any synthetic material. If it were transformed into a bulletproof vest, it would be three times more resistant than kevlar – used in bulletproof vests.

He has already found a number of uses – from fishing lines to dressings because he also has antibacterial properties. Like the hair, it is made of protein.

Co-author Claire Hsu, an undergraduate student in Professor Buehler's lab, said the international team had come across this discovery.

She said, "My colleagues and I wanted to study the influence of moisture on spider silk."

Spiders use a silk dragline, the strongest form, to stabilize in the air and control their landings.

The researchers hung a silk weight to create a kind of pendulum, and then locked it in a room where they could control the relative humidity in the interior.

Ms. Hsu explained, "When we increased the humidity rate, the pendulum started spinning.It was unexpected.This really shocked me."

The team tested a number of other materials, including human hair, but found no such twisting motion.

The possibility of artificial muscles came to them both – as a new way to control certain types of sensors or control devices.

Professor Buehler said, "This could be very interesting for the robotics community – the way you can control these movements by controlling the humidity is very accurate."

A number of teams around the world are striving to replicate the exceptional strength / weight, flexibility and resilience of spider silk in a synthetic version.

Professor Buehler thinks that the twisting movement has evolved to make sure the canvas is tight in response to morning dew.

This would protect it from damage and maximize its response to vibration so that the spider can detect its prey.

Professor Buehler said: "We have found no biological significance."

But laboratory experiments and computer models have shown that the mechanism is based on the folding of a particular type of protein building block, called proline.

Once in place, torsion has always occurred in molecular simulations. Without this, there was no twist.

Professor Co-author Dabiao Liu, Huazhong University of Science and Technology, Wuhan, China, said: "The dragline silk is a protein fiber and is made up of two main proteins, called MaSp1 and MaSp2. . "

Proline, essential for the torsion reaction, is found in MaSp2. When water molecules interact with it, they break its hydrogen bonds asymmetrically.

This causes the rotation. It only goes in one direction and is at a relative humidity threshold of about 70%.

Prof Buehler said: "The protein has an integrated rotational symmetry." And its torsion force makes possible "a whole new class of materials".

Now the property has been found, it opens the door to a synthetic spider silk that does exactly the same thing.

"Maybe we could make a new polymer material that would replicate that behavior."

Synthetic muscle technology currently relies on connected external compressors or high voltage equipment.

Anna Tarakanova, a professor at MIT and currently at the University of Connecticut, said: "The unique propensity of silk to undergo a super contraction and to exhibit torsional behavior in response to external triggers such as moisture can be exploited to design nanometrically sensitive silk-based materials.

"Potential applications are varied – from soft robots and sensors based on moisture, to smart textiles and green energy generators."

Other natural materials may also present this property – but, in this case, this has not been noticed.

Prof Buehler added: "This kind of twisting movement could be found in other materials that we have not examined yet."

In addition to the possible artificial muscles, the results could also lead to accurate moisture sensors.

True spider silk can only be collected in minute amounts. Spiders are very difficult to grow. They are predators and will easily resort to cannibalism in the absence of other prey.

Individual spiders have been captured and forced to rag under laboratory conditions but the quantities recovered are minimal.

Spiders produce only small amounts of silk, make only what they need for a canvas, then consume it to reuse the protein.

Until now, no one has been able to spin artificially spider silk fibers with the same mechanical properties as those made in nature by a spider.

But if we could, all of these ideas on how to use spider silk in various applications could become reality.

It is now possible to artificially make spider silk. Scientists now understand better how it is made by a scary little man on all fours.