Flexible - Page 4

Researchers at the Korean IBS, in collaboration with Sungkyunkwan University, have designed a novel graphene-based stretchable and flexible memory device for wearable electronics.

The team has constructed a memory called two-terminal tunnelling random access memory (TRAM), where two electrodes, referred to as drain and source, resemble the two communicating neurons of the synapse in the brain. While mainstream mobile electronics use the so-called three-terminal flash memory, the advantage of two-terminal memories like TRAM is that two-terminal memories do not need a thick and rigid oxide layer. While Flash memory is more reliable and has better performance, TRAM is more flexible and can be scalable, according to the team.

A team of researchers at Nanyang Technological University, Singapore, has produced a stretchy micro-supercapacitor using ribbons of graphene. The team produces stretchable electrodes and integrated them into a supercapacitor, in what can be seen as a promising step towards bendy power sources for flexible electronics.

In this study, the team focused on the fact that graphene can be flexible and foldable, but it cannot usually be stretched; They attempted to fix that problem by looking at skin, which has a wave-like microstructure, and started to think of how to make graphene also more like a wave. They started by making graphene nano-ribbons, having more control over its structure and thickness that way (which can affect the conductivity of the electrodes and how much energy the supercapacitor overall can hold).

Researchers from Korea's KAIST institute developed a rollable OLED device that uses graphene-based electrodes. The researchers say that the new OLED is much more durable when bent compared to current devices made with ITO electrodes.

The electrodes were made from a stack of materials - titanium oxdies, graphene and conductive polymers. The new OLEDs were also brighter than current devices, and with a higher color gamut. This was achieved by maximizing the resonance within the OLED.

A Chinese company (possibly called Interim, though details are sketchy) presented a fully bendable smartphone with a graphene-based screen during a trade show at Nanping International Conventional Center in Chongqing. The bendable touch display weighs 200g, and the smartphone can be worn around the wrist. The display is rumoured to be an OLED display with a diagonal of 5.2 inches.

There are no substantial details about the company behind the graphene smartphone and what the plans are to bring the graphene phone to market. It's not clear what the meaning of a "graphene-based" display is, in this case. While graphene can theoretically be used to make light emitting devices, it's highly unlikely that this is the case here. My guess would be that this is a flexible OLED display (could also be a flexible LCD, but that's unlikely) with a graphene-based touch panel.

Researchers at the University of Manchester have demonstrated how graphene's conductivity and flexibility will prove crucial to wearable electronic applications, opening the door to battery-free healthcare and fitness monitoring, phones, internet-ready devices and chargers to be incorporated into clothing and ‘smart skin’ applications (printed graphene-based sensors integrated with other 2D materials and put onto a patient’s skin to monitor temperature, strain and moisture levels).

The researchers printed graphene to create transmission lines and antennae and experimented with these in communication devices. They used a mannequin to which they attached graphene-enabled antennae on each arm, and found that the devices were able to communicate with each other, effectively creating an on-body communications system. These results show that such graphene-based components have the required quality and functionality for wireless wearable devices.

The Centre of Process Innovation (CPI) has announced that it will be part of a UK-based collaboration to develop the next generation of graphene-based ultra-barrier materials for flexible transparent plastic electronic based displays. The materials on which this work focuses on are required for the next generation of smartphones, tablets and wearable electronics and the twelve month project titled ‘Gravia’ will investigate the feasibility of producing graphene-based barrier films for next generation flexible OLED lighting and display products. 

The project combines the skills from each of the partners (University of Cambridge, FlexEnable Ltd, the National Physical Laboratory and the Centre for Process Innovation) and expects to deliver a feasible material and process system. It builds upon significant existing investments by InnovateUK and the EPSRC in this area. The resulting ultra-barrier material can be potentially used in a wide range of novel applications by the lead business partner, FlexEnable.

A few days ago we reported that the Fraunhofer Institute FEP will demonstrate an OLED device with a graphene-based electrode, as part of project GLADIATOR. The researchers hope that the graphene will enable devices that are highly flexible and stable. The CVD-produced monolayer graphene was produced by Graphenea, and the project that will run until April 2017 aims to produce larger demonstrators.

We had the good chance of talking to Beatrice Beyer, the project's coordinator at the Fraunhofer Institute, and she was kind enough to answer a few questions we had regarding the project and the technology they develop.

Q: Beatrice, thanks for your time. Can you explain to us how the graphene compares to ITO as an OLED electrode?

For the time being, the optoelectronic performance of graphene as a transparent electrode is still not as good as for the mature 'industry standard' ITO, but the performance and production technologies are continuously improving and we are optimistic that soon graphene based devices will reliably compete with ITO based on performance.

Researchers at Swinburne University of Technology, collaborating with Monash University, have developed an ultrathin, flat, lightweight graphene oxide optical lens with extraordinary flexibility, that enables potential applications in on-chip nanophotonics and improves the conversion process of solar cells. It might also open up new possibilities in areas like non-invasive 3D biomedical imaging, aerospace photonics, micromachines and more.

Recent developments in nano-optics and on-chip photonic systems have increased the demand for ultrathin flat lenses with 3D subwavelength focusing capability (the ability to see details of an object smaller than 200 nanometres). A number of ultrathin flat lens concepts have been developed, but their real-life application is limited due to their complex design, narrow operational bandwidth and time consuming manufacturing processes. This lens, however, has a 3D subwavelength capability that is 30 times more efficient, able to tightly focus broadband light from the visible to the near infrared, and offers a simple and low-cost manufacturing method.

As part of project GLADIATOR, The Fraunhofer Institute FEP will show an innovative organic light emitting diodes (OLEDs) with a graphene-based electrode at Plastic Electronics 2015. The fabricated OLED on transparent graphene electrodes has been realized on a small area, and the target of the next one and a half years of the project is to successfully achieve large area OLEDs.

With graphene as an electrode, the researchers at the Fraunhofer FEP hope for flexible devices with higher stability. The electrode contains CVD-produced monolayer graphene of high quality, supplied by Graphenea, in order to compete with the reference material ITO (which graphene, in this case, replaces), the transparency and conductivity of graphene must be very high. Therefore, not only the process of electrode manufacturing is being optimized, but also different ways of doping graphene to improve its properties are being examined.

Researchers at the University of Wollongong's Institute for Superconducting and Electronic Materials designed a graphene-based flexible, foldable, and lightweight energy storage device for use in next-gen wearable technology and also as a potential device for medical implants, like pacemakers.

The scientists devised a 3D structure:  liquid graphene was mixed with a polymer and the combination was then solidified to form the carbon nanotubes. The resulting structure was made-up of three parts: graphene, a conductive polymer, and carbon nanotubes. These three parts take the form of single atom-thick networks, resembling carbon formed cylinders. The novel design is efficient because by separating out the layers of carbon, researchers are able to use both surfaces in the structure for charge accumulation. The scientists expect this design to lead to ultra-fast and efficient battery devices.