New metallic material for ‘origami’ robots

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A team of National University of Singapore (NUS) researchers have developed a new metal-based material for use in soft robots.

‘Origami robots’ are being tested for use in various applications including drug delivery in human bodies, search and rescue missions in disaster environments and humanoid robotic arms. These are often made from soft materials such as paper, with sensors and electrical components then added on top.

As these add bulk to the devices, the research team set out to develop a material that could combine flexibility with enhanced capabilities.

They produced a metal-based material through a new process called ‘graphene oxide-enabled templating synthesis’. Cellulose paper was soaked into a graphene oxide solution, before dipping it into a solution made of metallic ions such as platinum. The material was then burned in an inert gas, argon, at 800°C and then at 500°C in air.

The final product was a thin layer of metal — 90 micrometres (μm), or 0.09mm — made up of 70 per cent platinum and 30 per cent amorphous carbon (more commonly known as ash).

“We experimented with different electrically conductive materials to finally derive a unique combination that achieves optimal strain sensing and wireless communication capabilities. Our invention therefore expands the library of unconventional materials for the fabrication of advanced robots,” explained Mr Yang Haitao, doctoral student at the Department of Chemical and Biomolecular Engineering.

The lightweight metallic material is three times lighter than conventional materials. It is also more power-efficient and is fire-resistant, making it suitable for fabricating robots that work in harsh environments as it can withstand burning at around 800°C for up to 5 minutes.

The conductive material also has geothermal heating capabilities. The researchers found that sending a voltage through the material causes it to heat up. This helps prevent ice damage should the robot be required to operate in a cold environment.

Its mechanically stable, soft, and conductive properties can be used for strain sensing and communication capabilities without the need for external electronics. The material can act as its own wireless antenna, allowing it to communicate with a remote operator or other robots without the need for external communication modules.

The researchers say this expands the scope of origami robots, such as working in high-risk environments as remote-control untethered robots or functioning as artificial muscles or humanoid robotic arms.