Lightweight and Metallic Material Developed for “Origami Robots”

“Origami robots” are sophisticated robots that are both soft and flexible. These robots are now being tested for use in different applications, such as humanoid robotic arms, search and rescue operations in disaster settings, and drug delivery in human bodies.

Since origami robots are required to be flexible, they are usually built from soft materials like rubber, plastic, and paper. To be functional, electrical components and sensors are usually added on top, but these tend to make the devices bulky.

Now, a research team from the National University of Singapore (NUS) has developed a unique approach to produce a novel metal-based material that could be used in these soft robots.

The innovative material is a combination of metals like platinum with burnt paper, or ash. This material not only has improved capabilities but also maintains the lightweight and foldability traits of conventional plastic and paper. As a matter of fact, the weight of this material is 50% less than paper, which also renders it more power-efficient.

These properties make the material a powerful candidate for building light and flexible prosthetic limbs that can be as much as 60% lighter when compared to their traditional equivalents.

Prosthetics like these can offer real-time strain sensing to provide feedback to the extent they are flexing. This would give users greater control and instant information—all without using any external sensors which otherwise would increase the weight of the prosthetics unnecessarily.

Such a metallic yet lightweight backbone is at least three times lighter when compared to traditional materials that are utilized to produce origami robots. Also, the backbone is more power-efficient, allowing origami robots to work faster using 30% less energy.

Moreover, the new material is impervious to fires, thus rendering it best suited for developing robots that operate in adverse settings since it can tolerate burning for up to 5 minutes at approximately 800 °C.

The new conductive material also has geothermal heating capabilities on-demand, which is an added benefit. In other words, the material heats up when a voltage is passed through it. This method helps prevent icing damage when a robot operates in cold surroundings.

These characteristics can be utilized for producing flexible, lightweight search-and-rescue robots that can enter dangerous places and, at the same time, provide feedback and communication in real time.

Research Breakthrough Published in Prestigious Science Robotics Journal

The material, which is composed of metal, is created using a novel process known as “graphene oxide-enabled templating synthesis.” This process was developed by the NUS team.

The process involves soaking cellulose paper into a solution of graphene oxide and then dipping it into a solution made of metallic ions like platinum. Subsequently, the material is burned in argon, an inert gas, at 800 °C and then at 500 °C in air.

The end product is a thin metal layer that measures 90 μm, or 0.09 mm, and is composed of 30% amorphous carbon (ash) and 70% platinum. The product is flexible enough to stretch, fold, and bend. This major innovation was reported in Science Robotics, a renowned scientific journal, on August 28^th, 2019. In addition to platinum, other metals like silver and gold can also be utilized.

Chen Po-Yen, team leader and Assistant Professor, utilized a cellulose template that was cut out in the shape of a phoenix for his study.

We are inspired by the mythical creature. Just like the phoenix, it can be burnt to ash and reborn to become more powerful than before.

Chen Po-Yen, Assistant Professor, Department of Chemical and Biomolecular Engineering, National University of Singapore

Conductive Backbone for Smarter Origami Robots

The material developed by the researchers can work as soft, mechanically stable, and conductive backbones, equipping robots with communication and strain sensing capabilities without any requirement for external electronics.

Since the material is conductive, it behaves as its own wireless antenna. This enables it to interact with other robots, including a remote operator, without using any external communication modules. This widens the opportunities for origami robots, like working in high-risk settings (for example, fire disaster and chemical spills) either as remote-control untethered robots, or working as humanoid robotic arms or artificial muscles.

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.

Mr Yang Haitao, Doctoral Student, Department of Chemical and Biomolecular Engineering, National University of Singapore

Haitao is also the study’s first author.

In the subsequent steps of their study, Assistant Professor Chen and his research group are looking for ways to add additional functions to the metallic backbone. One potential direction is to integrate electrochemically active materials to create energy storage devices in such a way that the material itself serves as its own battery. Such an approach can lead to the development of autonomously powered robots.

The researchers are working with other types of metals like copper, which will reduce the cost associated with the production of this material.

Video Credit: National University of Singapore