Tag Archives: elastomer

Electrode-filled elastic fiber for wearable electronics and robots

This work comes out of Switzerland. A May 25, 2018 École Polytechnique Fédérale de Lausanne (EPFL) press release (also on EurekAlert) announces their fibers,

EPFL scientists have found a fast and simple way to make super-elastic, multi-material, high-performance fibers. Their fibers have already been used as sensors on robotic fingers and in clothing. This breakthrough method opens the door to new kinds of smart textiles and medical implants.

It’s a whole new way of thinking about sensors. The tiny fibers developed at EPFL are made of elastomer and can incorporate materials like electrodes and nanocomposite polymers. The fibers can detect even the slightest pressure and strain and can withstand deformation of close to 500% before recovering their initial shape. All that makes them perfect for applications in smart clothing and prostheses, and for creating artificial nerves for robots.

The fibers were developed at EPFL’s Laboratory of Photonic Materials and Fiber Devices (FIMAP), headed by Fabien Sorin at the School of Engineering. The scientists came up with a fast and easy method for embedding different kinds of microstructures in super-elastic fibers. For instance, by adding electrodes at strategic locations, they turned the fibers into ultra-sensitive sensors. What’s more, their method can be used to produce hundreds of meters of fiber in a short amount of time. Their research has just been published in Advanced Materials.

Heat, then stretch
To make their fibers, the scientists used a thermal drawing process, which is the standard process for optical-fiber manufacturing. They started by creating a macroscopic preform with the various fiber components arranged in a carefully designed 3D pattern. They then heated the preform and stretched it out, like melted plastic, to make fibers of a few hundreds microns in diameter. And while this process stretched out the pattern of components lengthwise, it also contracted it crosswise, meaning the components’ relative positions stayed the same. The end result was a set of fibers with an extremely complicated microarchitecture and advanced properties.

Until now, thermal drawing could be used to make only rigid fibers. But Sorin and his team used it to make elastic fibers. With the help of a new criterion for selecting materials, they were able to identify some thermoplastic elastomers that have a high viscosity when heated. After the fibers are drawn, they can be stretched and deformed but they always return to their original shape.

Rigid materials like nanocomposite polymers, metals and thermoplastics can be introduced into the fibers, as well as liquid metals that can be easily deformed. “For instance, we can add three strings of electrodes at the top of the fibers and one at the bottom. Different electrodes will come into contact depending on how the pressure is applied to the fibers. This will cause the electrodes to transmit a signal, which can then be read to determine exactly what type of stress the fiber is exposed to – such as compression or shear stress, for example,” says Sorin.

Artificial nerves for robots

Working in association with Professor Dr. Oliver Brock (Robotics and Biology Laboratory, Technical University of Berlin), the scientists integrated their fibers into robotic fingers as artificial nerves. Whenever the fingers touch something, electrodes in the fibers transmit information about the robot’s tactile interaction with its environment. The research team also tested adding their fibers to large-mesh clothing to detect compression and stretching. “Our technology could be used to develop a touch keyboard that’s integrated directly into clothing, for instance” says Sorin.

The researchers see many other potential applications. Especially since the thermal drawing process can be easily tweaked for large-scale production. This is a real plus for the manufacturing sector. The textile sector has already expressed interest in the new technology, and patents have been filed.

There’s a video of the lead researcher discussing the work as he offers some visual aids,

Here’s a link to and a citation for the paper,

Superelastic Multimaterial Electronic and Photonic Fibers and Devices via Thermal Drawing by Yunpeng Qu, Tung Nguyen‐Dang, Alexis Gérald Page, Wei Yan, Tapajyoti Das Gupta, Gelu Marius Rotaru, René M. Rossi, Valentine Dominique Favrod, Nicola Bartolomei, Fabien Sorin. Advanced Materials First published: 25 May 2018 https://doi.org/10.1002/adma.201707251

This paper is behind a paywall.

Exceeding the sensitivity of skin with a graphene elastomer

A Jan. 14, 2016 news item on Nanowerk announces the latest in ‘sensitive’ skin,

A new sponge-like material, discovered by Monash [Monash University in Australia] researchers, could have diverse and valuable real-life applications. The new elastomer could be used to create soft, tactile robots to help care for elderly people, perform remote surgical procedures or build highly sensitive prosthetic hands.

Graphene-based cellular elastomer, or G-elastomer, is highly sensitive to pressure and vibrations. Unlike other viscoelastic substances such as polyurethane foam or rubber, G-elastomer bounces back extremely quickly under pressure, despite its exceptionally soft nature. This unique, dynamic response has never been found in existing soft materials, and has excited and intrigued researchers Professor Dan Li and Dr Ling Qiu from the Monash Centre for Atomically Thin Materials (MCATM).

A Jan. 14, 2016 Monash University media release, which originated the news item, offers some insights from the researchers,

According to Dr Qiu, “This graphene elastomer is a flexible, ultra-light material which can detect pressures and vibrations across a broad bandwidth of frequencies. It far exceeds the response range of our skin, and it also has a very fast response time, much faster than conventional polymer elastomer.

“Although we often take it for granted, the pressure sensors in our skin allow us to do things like hold a cup without dropping it, crushing it, or spilling the contents. The sensitivity and response time of G-elastomer could allow a prosthetic hand or a robot to be even more dexterous than a human, while the flexibility could allow us to create next generation flexible electronic devices,” he said.

Professor Li, a director of MCATM, said, ‘Although we are still in the early stages of discovering graphene’s potential, this research is an excellent breakthrough. What we do know is that graphene could have a huge impact on Australia’s economy, both from a resources and innovation perspective, and we’re aiming to be at the forefront of that research and development.’

Dr Qiu’s research has been published in the latest edition of the prestigious journal Advanced Materials and is protected by a suite of patents.

Are they trying to protect the work from competition or wholesale theft of their work?

After all, the idea behind patents and copyrights was to encourage innovation and competition by ensuring that inventors and creators would benefit from their work. An example that comes to mind is the Xerox company which for many years had a monopoly on photocopy machines by virtue of their patent. Once the patent ran out (patents and copyrights were originally intended to be in place for finite time periods) and Xerox had made much, much money, competitors were free to create and market their own photocopy machines, which they did quite promptly. Since those days, companies have worked to extend patent and copyright time periods in efforts to stifle competition.

Getting back to Monash, I do hope the researchers are able to benefit from their work and wish them well. I also hope that they enjoy plenty of healthy competition spurring them onto greater innovation.

Here’s a link to and a citation for their paper,

Ultrafast Dynamic Piezoresistive Response of Graphene-Based Cellular Elastomers by Ling Qiu, M. Bulut Coskun, Yue Tang, Jefferson Z. Liu, Tuncay Alan, Jie Ding, Van-Tan Truong, and Dan Li. Advanced Materials Volume 28, Issue 1 January 6, 2016Pages 194–200 DOI: 10.1002/adma.201503957 First published: 2 November 2015

This paper appears to be open access.