What Are Soft Robotics?

Harpreet Thandi and Ashley Carley

The word robot comes from the wordrobota meaning forced labour in Czech. Traditionally robots are solid machines able to carry out tasks and help humans. This is now changing as the exciting new area of ‘soft robots’ is developing, where robots are made from materials such as silicone, plastic, rubber and mechanical springs. Merging soft and solid robotics could make robots more versatile and functional.

Marine Machines

Robots that already exist bare a resemblance to humans and even other animals. In 2007, after her dad caught her a live octopus, Professor Cecilia Laschi of the BioRobotics Institute at the Sant’Anna School of Advanced Studies in Pisa, Italy, built her own.

Multiple octopi prototypes have been developed with tentacles made from wires and springs which can recreate a tentacle’s natural motion. Each tentacle can bend, stretch, curl, and behave in a very lifelike way.

These robots could be used for marine research projects and even exploring unknown areas of the ocean. This is an amazing opportunity to understand more about marine life, biology, and evolution. After all, we know less about the ocean than we do about space.

The biggest challenge is to get the robot’s ‘arm’ to curl, scrunch and stretch. An octopus’ longitudinal muscles shorten or bend when they contract. To mimic this, springs in the constructed ‘arms’ bend and then return to their original size.

By having a combination of wires inside the ‘arm’, it can bend around a hand. Imagine if, in the future, a soft robot could locate humans in an emergency, remove rubble and rescue survivors. This technique could work on land or in the water.

But this isn’t the only soft octopus in development. The ‘Octobot’ is the world’s first totally soft-bodied autonomous robot. It propels itself using its rubbery legs, half at a time, in a movement powered by gas from an internal chemical reaction.

This new area of robotics has many products in their prototype stage, currently. There are some limitations due the ‘softness’ of the designs; their motions are often unpredictable. The Octobot is relatively floppy and needs improving to a point where its movements are precise and responsive to its surroundings. Practical tests are needed to prove they are durable.

Human helpers

Soft robots may even be able to aid the human body in medical contexts. Soft robots can get into small spaces and even perform surgical operations, although non-toxic substances are required if the robotics are intended for use in the body.

There are many other applications that are not water-based. One invention, the ‘gripper hand’, has a variety of features that change depending on the size, weight, and slipperiness of the gripped object. The robotic hands could function in shops and bars, handling slippery bottles, boxes and bags, and be integrated into manufacturing machines and production lines.

The soft nature of this design could improve on the functionality, flexibility and dexterity of the present technologies. The hands can grip objects of any shape, from mushrooms and strawberries to bottles, demonstrating both delicacy and strength like the octopus model. This is different from the force and feedback systems that we had before.

Fabrics

At Harvard University’s Biodesign Lab, a new wearable robotic suit has been developed; an important movement for soft robotics. This ‘superhero’ suit has advantages over conventional exoskeletons – or Exosuits – which are uncomfortable and ill-fitting.

Exosuits allow heavy loads to be carried over long distances. The new Exosuit is constructed of nylon, polyester and spandex, making it more comfortable. Additionally, there are position and acceleration sensors for monitoring gait. A further development will involve swapping these with ‘stretchy’ sensors for a softer, more comfortable experience.

A new robotic fabric moves in response to an electric current. Shape-memory alloy coils are sewn in and can compress by 60%. These alloys track the fabrics movements. The fabric consist of stretch-sensitive silicone filaments that contain liquid metal.

The technology could be put on a sleeve to help injured, elderly or disabled people with their movement. The robotics also have various applications for space technology.  

Soft robotics have many advantages: the technology is relatively cheap, strong, flexible, versatile, and able to fit into small spaces.

However, there are some problems and limitations. Soft robotics have not been fully tested in an industrial environment, they haven’t undergone in-depth strength tests and they still need to be attached to a power source.

Read more:

Nature: Meet the Soft Cuddly Robots of the Future

EPFL: Soft Robots that Mimic Human Muscles

Harvard Biodesign Lab: Soft Robotics

Metallic Hydrogen: 80 years in the making

 

Ashley Carley

Rocket fuel, lightning-fast supercomputers and levitating trains are just three uses of the newly discovered metallic hydrogen – if, the Harvard scientists say, everything goes to plan.

Hydrogen is the lightest and most abundant of all the elements. It forms two thirds of every drop of water, and almost 75% of the gas in the Sun’s core. Alone, hydrogen is most often found floating around in its gaseous phase, but it has been predicted a metallic form may exist when exposed to intense pressure.

Two physicists at Harvard University claim to have isolated this incredibly rare form for the first time, in a paper published this week. By squeezing solid hydrogen between two diamonds at temperatures well below freezing, the researchers created pressures larger than those found at the centre of the Earth. In these conditions, the hydrogen atoms began to share their electrons. Using this new electron cloud, they could conduct electricity.

Isaac Silvera, who made the discovery alongside his colleague Ranga Dias, recognises the importance of his achievement, calling it the “holy grail of high-pressure physics.”

This breakthrough has been a long time coming; it has been over 80 years since Eugene Wignar and Hillard Bell Huntington made the first predictions about metallic hydrogen. Since then the goalposts have continually shifted. Estimates of the pressure required to make the substance have been continually revised upwards, from 25 gigapascals (GPa), 250,000 times above atmospheric pressure, in 1935, to the most recent estimate of 400-500 GPa.

Each time the prediction changed, it moved out of the range scientists were capable of recreating in a lab environment, making it somewhat of a carrot on a stick for researchers in the field. Jeffrey McMahon, theoretical physicist at Washington State University, told New Scientist that if the results were reproducible, the recent experiments had solved “one of the major outstanding problems in all of physics.”

It wasn’t easy – the synthetic diamonds had to be flattened, polished and heated to remove any imperfections that could result in cracking. They were then covered in alumina, an extremely hard material made from aluminium and oxygen that hydrogen could not leak through. The two diamonds were then crushed together with great force, and Dr Dias watched as the hydrogen between them turned from clear to black, until it began to shine. The force required was 495 GPa – higher than the pressure at the Earth’s core. Dr Dias then called Professor Silvera, and they took the measurements that would confirm their discovery.

The next step is to see if it retains its structure when compression is relaxed. Some predictions suggest it will be too unstable to survive at room temperature, and will gradually decay, although others have more hope. Graphite forms diamonds under high pressures and temperatures, but when the sources of compression and heat are taken away – the diamond remains. Scientists are hoping metallic hydrogen could act the same way once released from its diamond vice.

If it does, its potential applications are exciting. If the amount of energy used to create the metallic hydrogen can be released by breaking it down again, it could become the most powerful rocket fuel ever made. “We would be able to put rockets into orbit with only one stage, versus two, and could send up larger payloads, so it could be very important,” Professor Silvera says. Electronic systems would also be revolutionised, as “superconductors” could be made which reduce energy wastage in wires.

When Professor Silvera is asked what thinks will happen next, he responds “I don’t want to guess, I want to do the experiment.” After an 80-year wait, perhaps the suspense is great enough.