Roll to roll - Page 2

Versarien, the advanced materials engineering group, has provided an update on its activities in relation to graphene-enhanced power storage devices like batteries and supercapacitors. The primary goal of incorporating graphene into these devices, Versarien says, is to significantly increase power storage capacity and reduce charging times.

Versarien has been working with WMG (Warwick Manufacturing Group) and their partner companies and scientists at the universities of Warwick and Cambridge to collaborate on the production of power storage devices such as batteries and supercapacitors using Versarien's proprietary Nanene graphene nano platelets. Significant advances have been made through incorporating the Company's high quality graphene into these devices and the Company looks forward to commercial products becoming available in due course.

Researchers at MIT have developed a method that might enable the production of long rolls of high-quality graphene. The continuous manufacturing process can reportedly produce five centimeters of high-quality graphene per minute. The longest run was nearly four hours, and it generated around 10 meters of continuous graphene.

MIT is referring to the development as the first demonstration of an industrial, scalable method for manufacturing high-quality graphene that is tailored for use in membranes that filter a variety of molecules. These membranes could be used in biological separation or desalination, for example. The researchers drew from the common industrial roll-to-roll approach blended with chemical vapor deposition, a common graphene-fabrication technique.

A team led by the Department of Energy’s Oak Ridge National Laboratory, that also included scientists from University of Tennessee, Rice University and New Mexico State University, has developed a new method to produce large, monolayer single-crystal-like graphene films more than a foot long. The novel technique may open new opportunities for producing high-quality graphene of unlimited size and in a way that is suitable for roll-to-roll production.

The ORNL team used a CVD method — but with a twist. They explained in this work how localized control of the CVD process allows evolutionary, or self-selecting, growth under optimal conditions, yielding a large, single-crystal-like sheet of graphene. Large single crystals are more mechanically robust and may have higher conductivity, ORNL lead coauthor Ivan Vlassiouk said. This is because weaknesses arising from interconnections between individual domains in polycrystalline graphene are eliminated. Our method could be the key not only to improving large-scale production of single-crystal graphene but to other 2D materials as well, which is necessary for their large-scale applications, he added.

Fraunhofer scientists have developed biosensors with graphene electrodes, produced cheaply and simply by roll-to-roll printing. A system prototype for mass production has already been established. This may change the current situation in which cell-based biosensors can be quite expensive to make, which often prevents them from being used. Cost factors for sensors that perform measurements electrically are the expensive electrode material and complex production.

Cell-based biosensors measure changes in cell cultures via electrical signals. This is done using electrodes which are mounted inside the Petri dish or the wells of a 'well plate'. If added viruses destroy a continuous cell layer on the electrodes, for example, the electrical resistance measured between the electrodes is reduced. In this way, the effect of vaccines or drugs (for example) can be tested: the more effective the active ingredient is, the smaller the number of cells that are destroyed by the viruses and the lower the measured resistance change will be. Also toxicity tests, such as on cosmetic products, can function according to the same principle and may replace animal experiments in the future. Another advantage is that if biosensors are linked to an evaluation unit, measurements can be continuous and automated.

A team of researchers at the University of Minnesota and Northwestern University, USA, have developed a printing method to produce flexible graphene micro-supercapacitors with a planar architecture suitable for integration in portable electronic devices.

The new process, referred to as ‘self-aligned capillarity-assisted lithography for electronics’ (SCALE), begins with the creation of a polymer template, generated by stamping a UV-curable polymer with a PDMS mold. High-resolution inkjet printing is then used to deposit a graphene ink into the template, which is annealed using a xenon lamp to form the electrodes. In the final step, a polymer gel electrolyte is printed onto the template over the electrodes to complete the configuration.

Grafoid, a leading graphene R&D and investment company, announced its entry into the global industrial coatings market with the introduction of its patent pending GrafeneX graphene coatings technology. Grafoid describes the GrafeneX technologies as a cost-effective way of laying down graphene coatings on large surface areas.

GrafeneX is a novel technology that creates a platform for the deposition of graphene and chemically functionalized graphene coatings. This process provides Grafoid with the capability to apply its diverse graphene-based coatings to many different types of material substrates with controllable levels of surface coverage, thickness etc. to meet precise end user requirements.

Researchers from the University of Exeter have developed a new method for creating entire device arrays directly on the copper substrates used for commercial manufacture of graphene. Complete and fully-functional devices can then be transferred to a substrate of choice, such as silicon, plastics or even textiles.

This new approach is said to be cheaper, simpler and less time consuming than conventional ways of producing graphene-based devices, thus holding real potential to open up the use of cheap-to-produce graphene devices for a host of applications from gas and biomedical sensors to displays.

Researchers at MIT and the University of Michigan developed a new roll-to-roll manufacturing method, that promises to enable continuous production using a thin metal foil as a substrate, in an industrial process where the material is deposited onto the foil as it moves from one spool to another. The resulting size of the sheets would be limited only by the width of the rolls of foil and the size of the chamber where the deposition would take place.

The new process is an adaptation of a CVD method already used at MIT (and additional places) to make graphene. The new system uses a similar vapor chemistry, but the chamber is in the form of two concentric tubes, one inside the other, and the substrate is a thin ribbon of copper that slides smoothly over the inner tube. Gases flow into the tubes and are released through precisely placed holes, allowing for the substrate to be exposed to two mixtures of gases sequentially. The first region is called an annealing region, used to prepare the surface of the substrate; the second region is the growth zone, where the graphene is formed on the ribbon. The chamber is heated to approximately 1,000 degrees Celsius to perform the reaction.

The U.S based Graphene Frontiers, developer of graphene materials and device technology, announced securing a U.S patent (No. 8,822,308) for the transfer of graphene films between surfaces using roll-to-roll processes.

The patented process is meant to be a cost-effective, etch-free transfer process, allowing manufacturers to avoid dissolving or consuming the substrate metal. It is reportedly also compatible with other materials, including nanomaterials.

Researchers at Purdue University are developing a new graphene "nanopetals" mass production process. Those nanopetals are graphene-based vertical nanostructures that look like tiny rose petals, and they have applications in sensors, heat-management, supercapacitors and batteries. This research is funded with a $1.5 million grant from the NSF.

The researchers hope to increase the production speed of nanopetal-coated surfaces to 10 square meters per hour, using a roll-to-roll process. This is a dramatic increase to current "laboratory-scale" production rate. The new process will use a vacuum-based plasma-enhanced chemical vapor deposition (PECVD).