Daily Bulletin


The Conversation

  • Written by The Conversation
imageScientists have figured out how to make this...with graphene. McEuen Group, Cornell University

Material scientists have found a way to apply the ancient art of kirigami – a way of building complex structures by cutting and folding paper – to the wonder material graphene. The experiment shows that ripples in a graphene sheet can increase the bending stiffness of the material significantly more than expected – a discovery that could lead to new types of sensors, stretchable electrodes or tools for use in nanoscale robotics.

Graphene is a single layer of graphite, a naturally occurring mineral with a layered structure. The material, first produced in the lab in 2003, has impressive electrical, thermal and mechanical properties, which makes it potentially useful in applications ranging from new electronic devices to additives in paints and plastics.

The promising material is made up of carbon atoms structured in a series of interconnecting hexagons, similar to chicken wire. It is made by pulling apart the layers in graphite in what scientists call a “top-down” approach (where we take something big and make it smaller). This can be done using adhesive tape; chemical reagents; or by sheer force such as those generated in a kitchen blender or mixer. Although this sounds quite simple it is not suitable for producing large sheets of graphene.

To do this, a “bottom-up” approach is needed, where graphene is assembled by decomposing a carbon-containing molecule such as methane over a hot metal surface, typically copper. This is the technique the researchers in the new study used to produce a sheet of graphene that they then could manipulate using a version of kirigami.

imagePaper and graphene versions of kirigami. Graphene image taken using a transmission white-light optical microscope.McEuen Group, Cornell University

Art meets science

Kirigami (“kiri” means cut and “gami” means paper) is a type of origami (“ori” means fold) which has been practised for centuries to produce beautifully complex shapes and patterns. Lots of us have probably tried our hand at these techniques as children, making snowflakes out of scrap paper.

The researchers used gold pads as “handles” to crumple a graphene sheet like paper – in a process that is entirely reversible. Like paper, the graphene folds and crumples but does not noticeably stretch.

A gold pad (the dark square which measures a few 10’s of microns) is being pushed by a micromanipulator and is attached to a graphene spring

By using a sophisticated measuring technique, where an infrared laser is used to apply pressure to the gold pad on the graphene film, it is possible to measure the level of displacement of the graphene film. This displacement can then be used to workout the elastic properties of the graphene sheet. Wrinkling of the graphene sheet improves its mechanical properties, similar to how a crumpled sheet of paper is more rigid than a flat one.

In fact it was such mechanical similarities that enabled the researchers to translate ideas directly from paper models to graphene devices. Using photolithography, a method of transferring geometric shapes on a mask to a surface, as the “cutting scissors”, the team showed that it is possible to create a series of springs, hinges and stretchable graphene transistors.

Remotely-operated robotics?

The research has opened the door to manipulating two-dimensional graphene sheets to create new material structures with movable parts. The possibility of stretchable transistors is extremely interesting as there is a growing demand to develop flexible and even wearable electronics.

When stretching a material you would normally expect the electrical resistance to change. In the stretchable transistors developed in the new study, a graphene spring is sandwiched between a source and a drain electrode. When stretched to over twice its original size no noticeable change in electrical properties was detected. Repeated stretching and un-stretching also had little effect either.

Working in a water and soap solution, large sheets of graphene can dramatically crumpled like soft paper, and return to their original shape

This ability to maintain graphene’s electrical properties is down to its lattice structure, which does not undergo much change during the stretching of the spring. It even proved possible to take the kirigami devices to the next level, moving or folding the graphene without using direct contact. For example, by replacing the gold pads with a ferromagnetic material, such as iron, the sheets could be manipulated in a magnetic field, creating complex motions such as twists. The technique could be used to create devices that respond to light, magnetic fields or temperature.

The concept of manipulating two-dimensional materials to generate more complex structures on the macro-, micro- and nanoscale is genuinely exciting. Being able to create new metamaterials, engineered to have properties not usually found in natural materials, could open the door to many new types of tools. Possibilities include new sensors, stretchable electrodes that could be used in robotics or nanomanipulators, tiny machines that can move things around with nanometer precision.

Stretchable electrodes would allow highly conformable or flexible electronics and sensors to be incorporated into synthetic skin or flesh, such as in robots or artificial limbs, while retaining full functionality. We could even visualise such flexible electrodes and sensors being used in wearable electronics incorporated into clothing for realtime personal health monitoring – the ultimate personal healthcare.

Karl Coleman is affiliated with Applied Graphene Materials and is funded by EPSRC for graphene related work.

Authors: The Conversation

Read more http://theconversation.com/folding-graphene-like-origami-may-allow-us-to-wear-sensors-in-our-skin-45346

Writers Wanted

My best worst film: dubbed a crass Adam Sandler comedy, Click is a deep meditation on relationships

arrow_forward

As the Queensland campaign passes the halfway mark, the election is still Labor's to lose

arrow_forward

Two High Court of Australia judges will be named soon – unlike Amy Coney Barrett, we know nothing about them

arrow_forward

The Conversation
INTERWEBS DIGITAL AGENCY

Politics

Prime Minister Interview with Kieran Gilbert, Sky News

KIERAN GILBERT: Kieran Gilbert here with you and the Prime Minister joins me. Prime Minister, thanks so much for your time.  PRIME MINISTER: G'day Kieran.  GILBERT: An assumption a vaccine is ...

Daily Bulletin - avatar Daily Bulletin

Did BLM Really Change the US Police Work?

The Black Lives Matter (BLM) movement has proven that the power of the state rests in the hands of the people it governs. Following the death of 46-year-old black American George Floyd in a case of ...

a Guest Writer - avatar a Guest Writer

Scott Morrison: the right man at the right time

Australia is not at war with another nation or ideology in August 2020 but the nation is in conflict. There are serious threats from China and there are many challenges flowing from the pandemic tha...

Greg Rogers - avatar Greg Rogers

Business News

Important Instagram marketing tips

Instagram marketing is one of the most important approaches for digital advertisers. If you want to promote products online, then Instagram along with Facebook is the perfect option. After Faceboo...

News Co - avatar News Co

Top 3 Accident Law Firms of Riverside County, CA

Do you live in Riverside County and faced an accident and now looking for a trusted Law firm to present your case? If yes, then you have come to the right place. The purpose of the article is to...

News Co - avatar News Co

3 Ways to Keep Your Business Safe with Roller Shutters

If you operate your business in a neighbourhood or city that is not known for being a safe environment, it is not surprising if you often worry about the safety of your business establishments o...

News Co - avatar News Co



News Co Media Group

Content & Technology Connecting Global Audiences

More Information - Less Opinion