Boffins see light in powering robots

Local | Charlotte Luo 1 Jun 2018

HKU scientists discovered an existing material can be powered by visible light, electricity and other stimuli, and could potentially power robots in the future.

The findings were published on Science Robotics yesterday.

The material, nickel hydroxide-oxyhydroxide, is commonly used for nickel-metal hydride batteries.

A team at the Department of Mechanical Engineering at the University of Hong Kong discovered that the material can be instantaneously triggered by visible light and lift objects up to 3,000 times its own weight. The performance is repeatable for thousands of cycles. The team of scientists believe it has the potential to power robots in the future.

One of the big challenges in creating robots is finding new materials. Alfonso Ngan Hing-wan said light-induced actuating materials are highly desirable among various stimuli because they can wirelessly operate robots.

However, very few light driven materials were available in the past, and their materials and production costs were high, he said.

Since the major component is nickel, hydroxide-oxyhydroxide is easy and relatively cheap to produce as it only costs HK$4 per square meter and can be fabricated in three hours.

Other than visible light, hydroxide-oxyhydroxide can be also powered by electricity. It is also responsive to changes in heat and humidity and might potentially be applied in autonomous machines that harness the tiny energy change in the environment.

In a lab, Kwan Kin-wa demonstrated how a mini arm of two actuating hinges made of hydroxide-oxyhydroxide could lift an object 50 times its weight once the light was on.

He also showed how a mini walking-bot had its front log straightened with light and walks towards the light.

Ngan said the material can be easily scaled up and manufactured in factories.

The research cost about HK$400,000, and was funded by the Research Grants Council, Hong Kong.

Ngan said it will take an additional five to 10 years to study how the material can be applied before products are launched on the market.

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