Silicon-Based Artificial Muscles—A New Approach to Soft Robotics

October 01, 2017 by Zabrel Holsman

Engineers from the University of Columbia have created an artificial muscle that can lift over 1000 times its own weight.

Engineers from the University of Columbia have created an artificial muscle that can lift over 1000 times its own weight.

In the past ten years, there have been significant breakthroughs in our soft robotics technology, ranging from software upgrades to smaller and more compact hydraulic and gas-operated robots. In those ten years, our computing power has increased many times over. However, as with most other forms of technology, the goal has been to make our soft robotics smaller, more precise, and more powerful. Scientists’ ability to downscale the size of the mechanical components still remains a large challenge.

The large gap between computing power and mechanical components has created a momentous swing in soft robotics research, especially in alternative materials. One of these fields of research has targeted the replication of human muscle to potentially solve the size and power scaling issues with our current designs.

Our current soft robotic technology is based on pneumatic and hydraulic systems, which can be practical but usually require large external components such as a compressor. These can be extremely difficult to downsize to practical levels.

A research article published in the journal Nature describes a new approach to creating easily scalable synthetic muscle that can lift over 1000 times its own weight.


Creating Elastomer "Muscles"

The team of researchers from Columbia Engineering used a material known as a silicone elastomer and mixed it with an ethanol solution to 20%. The ethanol forms bubbles inside of the silicon at room temperature, creating an active fluid that can be excited with temperature increases.


Here is a picture of the muscle being inflated.


If the material is fed enough voltage, the ethanol inside of the silicone elastomer will boil and expand. The casing for the material then experiences enough pressure to increase its volume and when the ethanol cools the material will then decrease volume. This process creates an easily-controlled expansion and contraction of the material that can operate as an actuator. The synthetic muscle was capable of expanding itself to nine times its original size when heated to 176 degrees Fahrenheit using only 8 volts through a wire.

“Our soft functional material may serve as robust soft muscle, possibly revolutionizing the way that soft robotic solutions are engineered today,” said lead author Aslan Miriyev. “It can push, pull, bend, twist, and lift weight. It’s the closest artificial material equivalent we have to a natural muscle.”


A Promising Start, Despite Challenges

There is still a long way to go before the technology is going to see practical uses. While the material is capable of expanding its size many times (as well lifting a significant amount of weight), this expansion occurred over the course of a minute. This development could become a significant step in soft robotics and could see a broad view of applications, particularly in medicine.

Possibly the most intriguing part of their development, however, is that the device was made using a 3D printer that could print two materials simultaneously. This opens up the potential for industrial as well as consumer production. The actuator in all was relatively cheap to produce, but for now it is out of the hands of consumers.

Video courtesy of Professor Hod Lipson, University of Columbia
  • ArdRhi October 06, 2017

    Don’t those muscles work backwards? Meat muscles CONTRACT when actuated, while these EXTEND. You’d have to keep them all energized to slacken them, and contraction speed is limited to the speed at which they cool down. What if the device with the artificial muscles was put in a hot environment? Or a cold one? That’d mess up their ability to function.

    When they come up with a non-thermal artificial muscle that CONTRACTS when actuated, then they’ll really have something.

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    ronsoy2 October 06, 2017

    By running the output shaft through the center of the muscle out the other end the muscle will pull instead of push. Be innovative. But the slow reaction time is definitely a severe handicap.

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