Metalic material for flexible soft robots

Soft, flexible origami robots, made from paper, plastic, and rubber could support applications including robotic arms, drug delivery, and search and rescue missions. However, sensors and electrical components added on top bulk up devices, lowering utility.

Now, researchers from National University of Singapore (NUS) have developed a method for creating a metal-based material with enhanced capabilities that maintain foldability and reduce weight.

Half as light as paper, the material is more power efficient, making it a strong candidate for light, flexible prosthetic limbs – up to 60% lighter than conventional counterparts. Such prosthetics can provide real-time strain sensing to give feedback on how much they are flexing, giving users finer control and immediate information without using external sensors which would add unwanted weight.

This lightweight metallic backbone is at least 3x lighter than conventional materials used to fabricate origami robots and is more power- efficient, lowering energy use 30% while speeding operation.

Produced through graphene oxide-enabled templating synthesis, cellulose paper is soaked in a graphene oxide solution before being dipped in a solution made of metallic ions such as platinum. The material is then burned in inert argon at 800°C and then at 500°C in air.

The final product is a 90µm layer of metal made of 70% platinum and 30% amorphous carbon (ash) that’s flexible enough to bend, fold, and stretch. Other metals such as gold and silver can also be used.

Team leader and NUS Chemical and Biomolecular Engineering Assistant Professor Chen Po-Yen used a cellulose template cut out in the shape of a phoenix for his research, explaining that they were “inspired by the mythical creature. Just like the phoenix, it can be burnt to ash and reborn to become more powerful than before.”

Smarter origami robots

The team’s material can function as mechanically stable, soft, and conductive backbones that equip robots with strain sensing and communication capabilities without the need for external electronics – the material acts as its own wireless antenna, communicating with a remote operator or other robots without external communication modules.

“We experimented with different electrically conductive materials to finally derive a unique combination that achieves optimal strain sensing and wireless communication capabilities…expanding the library of unconventional materials for the fabrication of advanced robots,” says Yang Haitao, doctoral student at NUS and first author of the study.

Next, Chen and his team are looking at adding more functions to the metallic backbone. One promising direction is to incorporate electrochemically active materials to fabricate energy storage devices, allowing the material to be its own battery. The team is also experimenting with other metals such as copper, which will lower the cost of material production.

National University of Singapore (NUS)