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TDK sees hard drive breakthrough in areal density

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Engineers invent new device that could increase Internet

The device uses the force generated by light to flop a mechanical switch of light on and off at a very high speed........


Using light to control light: Engineers invent new device that could increase Internet download speeds

The device uses the force generated by light to flop a mechanical switch of light on and off at a very high speed. This development could lead to advances in computation and signal processing using light instead of electrical current with higher performance and lower power consumption. The research results were published today in the online journal Nature Communications.

University of Minnesota researchers have invented a novel microscale mechanical switch of light on a silicon chip.

"This device is similar to electromechanical relays but operates completely with light," said Mo Li, an assistant professor of electrical and computer engineering in the University of Minnesota's College of Science and Engineering.

The new study is based on a previous discovery by Li and collaborators in 2008 where they found that nanoscale light conduits can be used to generate a strong enough optical force with light to mechanically move the optical waveguide (channel of information that carries light). In the new device, the researchers found that this force of light is so strong that the mechanical property of the device can be dominated completely by the optical effect rather than its own mechanical structure. The effect is amplified to control additional colored light signals at a much higher power level.

"This is the first time that this novel optomechanical effect is used to amplify optical signals without converting them into electrical ones," Li said.

Glass optical fibers carry many communication channels using different colors of light assigned to different channels. In optical cables, these different-colored light channels do not interfere with each other. This non-interference characteristic ensures the efficiency of a single optical fiber to transmit more information over very long distances. But this advantage also harbors a disadvantage. When considering computation and signal processing, optical devices could not allow the various channels of information to control each other easily…until now.

The researchers' new device has two optical waveguides, each carrying an optical signal. Placed between the waveguides is an optical resonator in the shape of a microscale donut (like a mini-Hadron collider.) In the optical resonator, light can circulate hundreds of times gaining intensity.

Using this resonance effect, the optical signal in the first waveguide is significantly enhanced in the resonator and generates a very strong optical force on the second waveguide. The second waveguide is released from the supporting material so that it moves in oscillation, like a tuning fork, when the force is applied on it. This mechanical motion of the waveguide alters the transmission of the optical signal. Because the power of the second optical signal can be many times higher than the control signal, the device functions like a mechanical relay to amplify the input signal.

Currently, the new optical relay device operates one million times per second. Researchers expect to improve it to several billion times per second. The mechanical motion of the current device is sufficiently fast to connect radio-frequency devices directly with fiber optics for broadband communication.

Li's team at University of Minnesota includes graduate students Huan Li, Yu Chen and Semere Tadesse and former postdoctoral fellow Jong Noh. Funding support of the project came from the University of Minnesota College of Science and Engineering and the Air Force Office of Scientific Research.

From phys

Engineers collaborate on inexpensive DNA sequencing method

While sequencing the genome of an animal species for the first time is so common that it hardly makes news anymore, it is less well known that sequencing any single individual's DNA is an expensive affair, costing many thousands of dollars using today's technology. An individual's genome carries markers that can provide advance warning of the risk of disease, but you need a fast, reliable and economical way of sequencing each patient's genes to take full advantage of them. Equally important is the need to continually sequence an individual's DNA over his or her lifetime, because the genetic code can be modified by many factors.

Schematic of an artificial membrane, across which a voltage forces an ionized fluid through the nanopore. Nucleotides on a strand of DNA are first tagged with different-sized polymers, and then the strand is passed near the nanopore opening, where a polymerase cleaves the polymers and passes them one by one through the nanopore. As they pass, the pore produces a unique ionic current blockade signature due to the tag's distinct chemical structure, thereby determining DNA sequence.

Read more at: http://phys.org/news/2012-10-collaborate-inexpensive-dna-sequencing-method.html#jCp
Schematic of an artificial membrane, across which a voltage forces an ionized fluid through the nanopore. Nucleotides on a strand of DNA are first tagged with different-sized polymers, and then the strand is passed near the nanopore opening, where a polymerase cleaves the polymers and passes them one by one through the nanopore. As they pass, the pore produces a unique ionic current blockade signature due to the tag's distinct chemical structure, thereby determining DNA sequence.
Schematic of an artificial membrane, across which a voltage forces an ionized fluid through the nanopore. Nucleotides on a strand of DNA are first tagged with different-sized polymers, and then the strand is passed near the nanopore opening, where a polymerase cleaves the polymers and passes them one by one through the nanopore. As they pass, the pore produces a unique ionic current blockade signature due to the tag's distinct chemical structure, thereby determining DNA sequence.

Read more at: http://phys.org/news/2012-10-collaborate-inexpensive-dna-sequencing-method.html#jCp


The new method determines DNA sequences by attaching distinct molecular "tags" to each of the four chemical building blocks, or "bases," that comprise the genetic information in a strand of DNA—abbreviated as A, G, C and T. Each of these polymer tags can then be cut from the strand and passed, one by one, through a nanometer-size hole in a membrane. A steady stream of fluid and ions flows through this "nanopore," which is large enough to contain only one tag at a time. As the polymer tags are different sizes, the change in electrical current caused by altered fluid flow shows which of the four bases sits at each point on the DNA strand.

Nanopores and their interaction with polymer molecules have been a longtime research focus of NIST scientist John Kasianowicz. His group collaborated with a team led by Jingyue Ju, director of Columbia's Center for Genome Technology and Biomolecular Engineering, which came up with the idea for tagging DNA building blocks for single molecule sequencing by nanopore detection. The ability to discriminate between the polymer tags was demonstrated by Kasianowicz, his NIST colleague Joseph Robertson, and others. Columbia University has applied for patents for the commercialization of the technology.

Kasianowicz estimates that the technique could identify a DNA building block with extremely high accuracy at an error rate of less than one in 500 million, and the necessary equipment would be within the reach of any medical provider. "The heart of the sequencer would be an operational amplifier that would cost much less than $1,000 for a one-time purchase," he says, "and the cost of materials and software should be trivial."

Kasianowicz adds that a private company might create a large array of nanopores that can analyze a single individual's genome cut up into many short strands of DNA, each of which could be sequenced quickly. Such an array potentially could provide the low-cost sequencing needed for routine medical use.

From phys

TDK sees hard drive breakthrough in areal density

Perpendicular magnetic recording was an idea that languished for many years, says a TDK technology backgrounder, because the complexity of high-density magnetic recording technology stymied commercial development. "This method demands highly sophisticated thin-film process technologies to form microscopic single poles between multiple thin layers. Beyond that, a number of complex issues arise when trying to miniaturize single poles," said TDK. "One particularly difficult problem is overcoming pole erasure, the deletion of magnetic data due to remanent magnetization at the tip of the pole." 

 The magnetic head for thermal assist recording. Credit: via Tech-on.


As magnetic head manufacturers, TDK says it is now drawing on nano-level thin-film multilayering and processing technologies that clear the technological hurdles one by one. TDK features a Tunneling Magneto-Resistance (TMR) head , which uses thermal assist recording and a near-light field. (Researchers from Hitachi describe thermally assisted recording as an extension to perpendicular magnetic recording. In thermally-assisted recording, says Hitachi, magnetic grains can be made smaller while still resisting thermal fluctuations at room temperature.) Consumers are to see these hard drives using thermal assisted magnetic heads in 2014. Before that, though, 

TDK will officially unveil its new hard-drive technology this week at CEATEC Japan 2012. At CEATEC, the company will also show a thermal assist recording method based on near-field light by using an actual HDD supporting the method. A significant side story belongs to Showa Denko, which, among other divisions, engages in hard disk media. Showa Denko also has a confident grasp of the disk drive market: "We expect that demand for hard disk drives (HDDs) will continue to grow by about 10 percent annually. " Hard disk drives for years have been a dominant device for storage of data. Greater capacities and lower prices have kept the hard drive from falling victim to SSD technology. Showa Denko believes HDDs still have nowhere to go but up because of notebook demand, cloud computing, and current requirements for high-capacity servers at data centers, expected to increase. To meet the demand, the company intends to "speedily commercialize the sixth-generation PMR (perpendicular magnetic recording) media, and develop the next-generation SWR (shingled-write recording) media."

From phys