Overcoming limitations of magnetic storage


Purdue-signatureResearchers at Nano-Meta Technologies Inc. (NMTI) in the Purdue Research Park have shown how to overcome key limitations of a material that could enable the magnetic storage industry to achieve data-recording densities far beyond today’s computers.

The new technology could make it possible to record data on an unprecedented small scale using tiny “nanoantennas” and to increase the amount of data that can be stored on a standard magnetic disk by 10 to 100 times.

The storage industry’s technology strategy, called heat-assisted magnetic recording (HAMR), hinges on the design of the nanoantenna, or near-field transducer (NFT), said Urcan Guler, chief scientist at Nano-Meta Technologies.

HAMR harnesses “plasmonics,” a technology that uses clouds of electrons called surface plasmons to manipulate and control light. However, some of the plasmonic NFTs under development rely on the use of metals such as gold and silver, which are not mechanically robust and present a challenge in fabrication and long-term reliability of the HAMR recording head.

Researchers from Nano-Meta Technologies and Purdue Univ. are working to replace gold with titanium nitride. The material offers high strength and durability at high temperatures, and its use as a nanoantenna paves the way for next-generation recording systems, said Vladimir M. Shalaev, scientific director of nanophotonics at Purdue’s Birck Nanotechnology Center and a distinguished professor of electrical and computer engineering.

The researchers have modified the physical properties of titanium nitride, tailoring it for HAMR.

A team from Nano-Meta Technologies and Purdue has authored an article on the need to develop new materials as alternatives to gold and silver for various plasmonic applications, using HAMR as an example. The article was published online in Faraday Discussions.

The technology could make it possible to circumvent the disk-storage-capacity limits imposed by conventional magnetic recording materials.Normally, lenses cannot focus light smaller than the wavelength of the light itself, which is hundreds of nanometers across. However, nanoantennas allow light to be focused into spots far smaller than the wavelength of light, making it possible to increase the storage capacity of the medium.

Industry has been reluctant to adopt titanium nitride for potential new plasmonic applications because making nanoantennas out of conventional titanium nitride leads to excessive “self-heating” through absorption of the input laser light, hindering performance. Common titanium nitride also undergoes oxidation reactions at high temperatures that degrade its optical properties, said Ernesto Marinero, a professor in Purdue’s School of Materials Engineering who is an expert in magnetic recording and joined the university after a long career in the storage industry.

To address both problems, the researchers have modified titanium nitride to significantly reduce its intrinsic light absorption, thereby paving the pathway to overcome the self-heating roadblock.  Furthermore, the researchers also have solved the oxidation problem by protecting the material with an ultrathin coating that prevents oxidation without affecting the material’s optical properties.

HAMR uses a laser to illuminate a nanoantenna, a tiny structure with the ideal shape and size for “optimum light coupling” to produce the required spot size onto the recording medium. The antenna couples electromagnetic energy into a small spot, creating heat that allows a magnetic head to write the ones and zeroes required for data storage onto a spinning disk. HAMR allows the use of recording materials with superior magnetic properties to guarantee the stability of the nanoscale ones and zeroes of future computer drives.

Source: Purdue Univ.

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Startup scales up graphene production, develops biosensors and supercapacitors


An official of a materials technology and manufacturing startup says his company is addressing the challenge of scaling graphene production for commercial applications.Startup scales up graphene production, develops biosensors and supercapacitors

Glenn Johnson, CEO of BlueVine Graphene Industries Inc., said many of the methodologies being utilized to produce graphene today are not easily scalable and require numerous post-processing steps to use it in functional applications. He said the company’s product development team has developed a way to scale the production of graphene to meet commercial volumes and many different applications.

“Our graphene electrodes are created using a roll-to-roll chemical vapor deposition process, and then they are combined with other materials utilizing a different roll-to-roll process,” he said. “We can give the same foundational graphene electrodes entirely different properties, utilizing standard or custom materials that we are developing for our own commercial products. In essence what we’ve done is developed scalable graphene electrodes that are foundational pieces and can be easily customized to unique customer applications.”

Timothy Fisher, founder and Chief Technology Officer of BlueVine Graphene Industries, developed the technology. He also is the James G. Dwyer Professor of Mechanical Engineering at Purdue. The patented technology has been exclusively licensed to BlueVine Graphene Industries through the Purdue Office of Technology Commercialization.

“We’re moving up to roll-to-roll, large-scale manufacturing capabilities. These roll-to-roll systems allow us to increase output by a thousand-fold over the original research-scale processes,” Fisher said. “These state-of-the-art systems allow us to leverage the game-changing properties of graphene and, in particular, our graphene petal technology, called Folium™, at production scales that provide tremendous pricing advantages.”

BlueVine Graphene Industries already is developing and testing two commercial applications for its Folium technology: biosensors and supercapacitors. Johnson said the company’s first-generation glucose monitoring technology could impact the use of traditional testing systems like lancets, which are made with gold and other precious metals. The second-generation technology could allow people to use non-invasive methods to test their glucose levels through saliva, tears or urine.

“Patient non-compliance with doctor-recommended glucose testing frequency can be a problem. By making lancets more affordable and potentially non-invasive, we are addressing a critical global need,” he said. “More frequent tests could lead to better control of the disease, which could lead to an associated reduction in health risks.”

Supercapacitors are BlueVine Graphene Industries’ second application under development for its Folium graphene. Johnson said the company’s graphene supercapacitors are reaching the energy density of lithium-ion batteries without a similar energy fade over time.

“Our graphene-based supercapacitors charge in just a fraction of the time needed to charge lithium-ion batteries. There are many consumer, industrial and military applications,” he said. “Wouldn’t it be great if mobile phones could be fully recharged in only a matter of minutes, and if they kept working like new, year after year?”

Johnson said the company will refine its production and quality assurance processes to produce commercial volumes of the Folium graphene.

“We also are focused on working with potential customers to continue to develop baseline products for both our biosensor and supercapacitor applications,” he said.
Source: http://www.purdue.edu/newsroom/…