Flexible - Page 7

Researchesr from Korea's Ulsan, KAIST and ETRI institutes developed a process that produces flexible transparent graphene electrodes that can be attached to the skin (or any kind of delicate object). This could enable applications such as electronic tattoo-like stickers or bio-signal sensors.

A graphene metal fiber composite ise used, which lowers the resistance of the transparent electrode to approximately 1/20th of existing ones. This enables the electrodes to be used in flexible displays or sensors. The new process is similar to a widely-used semiconductor process which means that this can be scaled commercially.

Electrochromic displays are made from materials in which the transmittance of light to be adjusted by applying a voltage. These work similarly to LCDs by letting light from a backlighting unit (BLU) pass or not and so show desired images. These kind of displays haven't been commercialized successfully yet due to fragile materials and material mismatches with the electrodes.

But this may change now, thanks to graphene. Researchers at Bilkent University developed a graphene electrochromic device that demonstrated 55% modulation and a broad spectral response. Both the electrode and the electrochromic device are made from graphene, and this enables a high percentage optical modulation, optical tuning properties in the UV to infrared, good electrical conductivity with no material mismatches. The display is mechanically flexible.

MIT researchers discovered that crumpling graphene paper (made from graphene sheets bonded together) results in a low-cost material that is very useful for extremely stretchable supercapacitors for flexible devices.

Crumpling the graphene paper results in a "chaotic mass of folds. The researchers developed a simple supercapacitor using this material, that can easily be bent, folded, or stretched to as much as 800% of its original size. The material can be crumpled and flattened up to a 1,000 times, without a significant loss of performance.

Researchers from Seoul National University managed to grow gallium nitride (GaN) micro-rods on a graphene sheet. This enabled them to create transferable LEDs and may enable the fabrication of bendable and stretchable devices.

The researchers say that graphene is the "perfect substrate" because it provides the desired flexibility with excellent mechanical strength, and it's also chemically and physically stable at temperatures in excess of 1,000 degrees Celsius. GaN combined with graphene substrates also shows excellent tolerance for mechanical deformation.

In June 2013, Cambridge University's Graphene Centre (CGC) and Plastic Logic started to develop a transparent graphene-based backplane for flexible displays. Now Plastic Logic demonstrated the first display that was developed in that collaboration research. Plastic Logic says that this is the first time graphene has been used in a transistor-based flexible device.

The prototype (shown above) is an active-matrix electrophoretic (E Ink) display fabricated on flexible plastic. The electrodes are made from solution-processed graphene which was patterned after deposition with micron-scale features. The prototype has a pixel density of 150 PPI and was made at low temperatures (less than 100 degrees celsius). This is just a prototype of course and you can see many defects in display.

Researchers from MIT developed a flexible transparent graphene-based electrode for graphene polymer solar cells (PSC). They report that this is the most efficient such electrode ever developed, with power conversion efficiencies of 6.1% (anode) and 7.1% (cathode).

To achieve the record efficiencies, the researchers thermally treated the MoO3 electron blocking layer and directly deposited a ZnO electron transporting layer on the graphene. The researchers say that the process is simple and reproducible.

The National Science Foundation of China (NSFC) awarded an 18-month Young International Researcher Fellowship to a University of Cambridge researcher that will look to se graphene materials composites for organic optoelectronic compounds. The researcher hope to use inkjet printers to produce those devices and then integrate them into displays, light detectors and gas sensors.

In plain English, it means that they hope these kind of devices will enable flexible, cheap and fast cameras. Compared to current printed organic circuits, the graphene-based will be less sensitive to temperature and moisture and will also offer much faster response time that is suited for photodetection.

Researchers from Boston University discovered that making patterned cuts in graphene can enable it to become stretchable - to more than 160% of their original size (regular graphene will be torn after stretched by 30%). This research uses an approach that is similar to the Japanese paper-cutting technique kirigami. The researchers say that it such stretchable graphene can be used to fabricate flexible sensors or foldable TV screens.

The researchers have used computer simulations, and have not performed real experiments yet. Those patterned sheets look like intricate snowflakes or flowers. The best pattern, they discovered, was numerous overlapping rectangles.

Vorbeck Materials announced the Vor-Power straps, a light-weight flexible power source that can be attached to any existing bag strap to enable a mobile charging station (via 2 USB and one micro USB ports). The Vor-Power strap weighs 450 grams and provides 7,200 mAh. And it's probably the world's first graphene-enhanced battery.

The Vor-Power strap is also very rugged - it is water resistant and can survive a drop of over 24 meters. You can pre-order it now for $89.99 (the regular price, after July 15, will be $129.99). Vorbeck will ship this product by July. They also offer custom versions with your logo or marketing message.

Researchers from Australia and Ireland developed a flexible yarn made from graphene oxide. This strong, lightweight, highly conductive and high capacitance fiber may be a great material for wearable textiles.

The researchers report that the new yarns and fibers exhibit the best electrochemical capacitance ever - of as high as 410 F/g. To create the fiber, the researchers used a novel wet-spinning technique that can produce both GO and r-GO yarns of unlimited lengths. Those yarns are strong (with a Young’s modulus that is greater than 29 GPa), have a high electrical conductivity of around 2500 S/m and a very large surface area about 2600 m2/g for graphene oxide and 2210 m2/g for the reduced material.