Soft Robotics and the Materials That Could Revolutionize the Field

Megan Ray Nichols

If someone says robotics, your mind likely conjures either an image of Arnold Schwarzenegger in The Terminator or a sharp looking piece of metal and plastic scuttling across the floor. It’s not the fear of Skynet that keeps us from advancing, though. It’s the materials that are currently available for the development of robotics. Recent innovations in material construction, however, could change the way we look at robotics forever. Let's take a look its sub-field soft robotics.

What is ‘Soft Robotics’?

Soft Robotics and the Materials That Could Revolutionize the Field

Soft-Body Fishlike Robot [Image source: Wikimedia Commons]

Soft robotics is a term that is growing in popularity. It references how these robots won't have the sharp edges, and hard grips that accompany traditional robotics. Soft robotics have softer edges and a more delicate touch. This enables them to complete work classic robots can’t accomplish.

Traditionally, in order to pick something up with a robotic arm, you needed to know the size specifications of the item and program them into the computer. Trying to pick up something fragile, like an egg usually results in an omelet.

Soft robotics utilizes softer, more flexible materials in its construction. In most cases, they can pick up objects of varying size and shape without programming each specific item.

What sorts of materials apply to soft robotics?

Printed Liquid Metal for Flexibility

When you think of an inkjet printer, you probably think of the office printer sitting on your desk. Have you ever imagined an inkjet printer that prints metal?  Printed liquid metal utilizes inkjet technology to print the flexible electronics used in soft robots.

Normal liquid metal would be too thick to pass through an inkjet head. To make it printable, the metal nanoparticles are mixed with a solvent like ethanol. It allows the metal to pass through the printing head into the desired pattern.  Once printed, the ethanol evaporates and leaves the liquid metal behind.

Once the printed metal is pressed to make the particles join, the metal is once again able to conduct data or electricity. The material’s potential applications are currently being studied, as well as how the liquid metal reacts to various surfaces. Current uses in the field of electronics include electrodes, interconnects and antennas. The flexibility of liquid metal lends itself well to soft robotics.

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Liquid Silicone Rubber for Soft Bodies

Liquid silicone rubber is arguably one of the most versatile tools being used for soft robotics. It can be molded into just about any shape. LSR is a durable and flexible material, resistant to mold and bacteria. It can also have hardware and circuits embedded directly into it.

Soft Robotics and the Materials That Could Revolutionize the Field

A SEM micrograph of the side view of a silicone rubber surface [Image source: Wikimedia Commons]

A variety of applications commonly use three different types of LSR:

- Food-grade LSR — Safe for use with food, often used to mold everything from cakes to gelatin treats.

- Medical-grade LSR — Useful for rubber tools and implants. Medical-grade LSR can be autoclaved for sterilization and provides amazing versatility in a variety of applications at a stunning variety of temperatures. It is also chemically stable. Chemicals or cleaning agents that it might come into contact with won't affect it.

- Conductive LSR — Designed to conduct electrical signals directly through the material. Ideal for use in flexible circuits and soft robotics.

While LSR is not currently able to be 3D printed, it can be molded in 3D printed molds, making the possible applications nearly endless. Its most recent use of soft robotics was in the Octobot, which Harvard scientists built in 2016. This fluid circuitry inside its soft rubber body was a new leap in soft robotic technology.

Metallic Glass for Durable Gears

Another game changer in the field of robotics is metallic glass. While ‘metallic glass’ might sound like an oxymoron, it’s actually the best new material for smooth motion gears for robotic movement.

Normally, when you melt metal, the atoms move about randomly, and when cooled, they solidify in a random arrangement. Metallic glass isn’t a mixture of metal and glass — on the contrary, it's metal that is heated and cooled quickly to the perfect temperature to trap it in a crystalline state. The crystalline state effectively turns metal into glass.

Soft Robotics and the Materials That Could Revolutionize the Field

Bulk metallic glass sample [Image source: Wikimedia Commons]

These gears are perfect for brutally cold environments, such as Mars. The gears can function without any sort of lubrication even at the coldest temperatures.  Curiosity, the rover currently on Mars, has to heat up the gear lubricant every time it needs to change position. With these new metallic glass gears, a rover could function on Jupiter’s moon Europa, which never gets warmer than -260 degrees F (-160 C) without the need for gear lubricant.

As we spread further out into the solar system, we will need materials like metallic glass to be able to construct equipment that can survive frigid environments. Unfortunately, this material works best at cold temperatures and might not work well in hot conditions such as those that we would face on Mercury or Venus.

Applications for Soft Robotics

Soft robotics has so many applications that we haven’t even thought of yet, from medicine to space travel and everything in between. Soft robots made of medical-grade LSR can be used to minimize surgical damage during minimally invasive robotic surgeries. Traditional surgical robots have very hard edges and don’t move as smoothly as soft robots do.

On Mars or beyond, soft robots could be the hands that build the habitats that we will need to support human life beyond our home planet. Researchers are already working on a soft robot designed to swim through the icy oceans of Europa.

Soft robots won’t look like anything that we associate with robotics. They will walk across the surface of alien planets. They'll make discoveries in places that no human could ever hope to survive. They have the potential to change robotic medicine and improve the efficacy of robot-assisted surgeries. Soft robots could squeeze into the smallest cracks to find survivors trapped under rubble, burrow through the loose soil to find landmines to keep soldiers or civilians safe or swim to the depths of the ocean to find what we have yet to discover.

If you want your own protocol droid to walk around behind you, you might be disappointed. With the trend toward soft robotics, your protocol droid might be a little squid that sits on your shoulder or a robotic dog that follows at your heels.

With soft, moldable materials can function in both harsh and friendly environments, the possibilities and applications are limited only by our imagination.

[Featured image source: Lori Sanders/ Harvard University ]

SEE ALSO: This New Soft Robot Could Save Lives of People With Heart Conditions

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