Engineers Invent New Actuating Material That Can Replace Motors in Future Robots

This new compact material can be used as artificial muscles for micro- and biomimetic-robots.

A team of mechanical engineers at the University of Hong Kong introduced a revolutionary actuating material that can be powered using visible light, electricity and other stimuli such as heat and humidity without any additional fabrication procedures. Nickel Hydroxide – Oxyhydroxide, the new material instantaneously responds to the stimuli and produces a force through deformation that corresponds to 3000 times its own weight.

There is an extensive research going on in developing new actuating materials, specifically to be used in robots which are mostly motor-driven. The motors, however, make the system bulky complex to operate.


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The latest actuating material, however, can be used to develop micro- and biomimetic robots, artificial muscles and medical devices that can be operated wirelessly. This will significantly reduce the complexities associated with the operation of robotic system or device.

The actuation is possible with the new material because of the volume change stimulated by visible light of low intensities. The engineers intentionally electroplated the material on selected areas of the substrate to serve as a hinge actuator to lift the objects by bending or curling in presence of light.

As opposed to the costly light-driven materials, the new nickel hydroxide – oxyhydroxide material contains mostly Nickel, which reduced the material cost significantly. According to the research, a typical actuator costs as low as HKD 4 per cm2 and is easy to fabricate.

Since the fabrication only requires electrodeposition, the fabrication process takes less than 3 hours, making it possible to scale up and manufacture the material in the industry.

The HKU engineers demonstrated the capability of the new-found material by integrating it into a “mini-arm” made up of two hinge actuators. Upon illumination, the arm is easily capable to lift an object 50 times of its weight.

Engineers Invent New Actuating Material That Can Replace Motors in Future Robots
Source: The University of Hong Kong

In another demonstration, the researchers made a mini walking robot with only front legs bending and straightening in presence of light, allowing it to move towards the light source.

Engineers Invent New Actuating Material That Can Replace Motors in Future Robots
Source: The University of Hong Kong

Given the revolutionary capabilities of the material, it can be applied to different applications in the future, specifically to develop micro-robots for rescue operations. Nickel hydroxide – oxyhydroxide is also the world’s first material system that can be actuated by visible light and electricity without needing additional fabrication process.

The researchers also suggested that with the intrinsic actuating properties of this material, it is possible to develop artificial muscles comparable to mammalian skeletal muscles by scaling up the fabrication. The research also opens up new opportunities to further study the light-induced actuating behavior of hydroxide-oxyhydroxides, which apparently has never been reported before.

This remarkable study was led by Professor Alfonso Ngan with a team of researchers from the Department of Mechanical Engineering at HKU. Their research was recently published in the Journal of Science Robotics.