IBM builds IC around single nanotube

YORKTOWN HEIGHTS, N.Y. - IBM researchers reported that they built the first complete electronic integrated circuit around a single carbon nanotube using standard semiconductor processes. The single molecule was the base for all components in the circuit, rather than linking together individually constructed components. The team argued that this approach can simplify manufacturing and provide the consistency needed to more thoroughly test and adjust the material for use in these applications.

The circuit is a ring oscillator, which chip makers typically build to evaluate new manufacturing processes or materials. The circuit stresses certain properties that can give a good indication of how new technologies will perform when used to build complete chips.

At bottom, a completed carbon nanotube circuit is compared to a human hair. The pictures on the right are magnifications of the same structure with the upper most showing the carbon nanotube covered by the contact and gate electrodes. Image courtesy of IBM
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By integrating the complete circuit around a single nanotube, the IBM team observed circuit speeds nearly a million times faster than previously demonstrated circuits with multiple nanotubes. The scientists will now use the ring oscillator to test improved carbon nanotube transistors and circuits, and to gauge their performance in complete chip designs.

Their research appeared in the March 24 issue of the journal Science.

MIT team uses viruses to make structures for batteries

CAMBRIDGE, Mass. - Massachusetts Institute of Technology scientists have harnessed the construction talents of tiny viruses to build nanowire structures for use in thin lithium-ion batteries. By manipulating a few genes inside viruses, the team was able to coax the organisms to grow and self-assemble into a functional electronic device. Their findings appeared in the April 7 issue of Science.

The goal of the work, led by MIT professors Angela Belcher, Paula Hammond and Yet-Ming Chiang, is to create batteries that cram as much electrical energy into as small or lightweight a package as possible. Batteries consist of two opposite electrodes, an anode and cathode, separated by an electrolyte. The team manipulated the genes in viruses, making the microbes collect exotic materials such as cobalt oxide and gold.

Georgia Tech’s technology proves faster, more versatile than AFM

ATLANTA - Georgia Institute of Technology researchers have created a highly sensitive atomic force microscopy technology capable of imaging 100 times faster than current AFM. The researchers reported in the February issue of Review of Scientific Instruments that FIRAT (Force sensing Integrated Readout and Active Tip) is not only much faster than AFM, but it also can capture other measurements never before possible with AFM, including material property imaging.

The key to the technology is a new microphone-inspired probe. Current AFM scans surfaces with a thin cantilever with a sharp tip at the end. An optical beam is bounced off the cantilever tip to measure the deflection of the cantilever as the tip moves over the surface and interacts with the material being analyzed.

Levent Degertekin, an associate professor of mechanical engineering at Georgia Tech, holds the new FIRAT next to the much larger AFM part it replaces. Photo courtesy of Georgia Tech
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FIRAT works like a cross between a pogo stick and a microphone. In one version of the probe, the membrane with a sharp tip moves toward the sample and just before it touches, it is pulled by attractive forces. Much like a microphone diaphragm picks up sound vibrations, the FIRAT membrane starts taking sensory readings well before it touches the sample. When the tip hits the surface, the elasticity and stiffness of the surface determines how hard the material pushes back against the tip. Rather than just capturing a topography scan of the sample, FIRAT can pick up a wide variety of other material properties.

Low-cost bioMEMS catheter passes lab, human tests

ADELAIDE, South Australia - A low-cost disposable BioMEMS catheter that can measure swallowing pressure has been developed by a University of South Australia research team using intelligent manufacturing processes.

The new catheter has many advantages over existing catheters, according to UniSA research fellow Hung-Yao Hsu, including lower risk of infection, better readings and greater patient comfort. Hsu is developing the catheter with the Women’s and Children’s Hospital.

The catheter recently passed a major milestone, with the design concept being verified through tests in laboratories and on humans. Sensor samples for the research were provided free of charge from Silicon Microstructures Inc. in California. Hsu expects the first disposable catheter to be launched in two years’ time.

NEC uses nano process to make sensor that evaluates circuits

TOKYO - NEC Corp. announced in February that it developed what it calls the world’s smallest fiber-optic electric field probe using a nanotechnology process. The probe consists of an optical fiber and an electro-optical film that is formed at its edge, which acts as a field sensor. The probe can be inserted into narrow spaces to evaluate the electrical characteristics of high-density packaged electronic circuits on printed circuit boards.

The probe was created based on aerosol deposition, which was developed by the National Institute of Advanced Industrial Science and Technology in Japan. This process involves a recently developed ceramics film formation technology, which can directly deposit complex oxide films that consist of nanoparticles on any kind of substrate material. NEC was able to develop the film processing techniques for sensing electric fields by adopting the aerosol deposition method for electro-optical film deposition.

Brookhaven’s nanodrops work helps advance lab-on-a-chip devices

UPTON, N.Y. - Scientists from Brookhaven National Laboratory discovered that drops of liquid with thicknesses of just a few nanometers are shaped differently than macroscopic liquid drops. Their results, published in the Feb. 9 online edition of Physical Review Letters, help elucidate the behavior of nanoscale amounts of liquid and, as a result, may help advance lab-on-a-chip and other developing technologies.

To create the tiny liquid drops, the researchers began with a solid surface patterned with a series of ultra narrow lines, ranging from 70 to 300 nanometers wide. These lines have different chemical properties than the rest of the surface, which makes them “attract” the liquid to form nanoscale drops.

Several nanoscale liquid lines of ethyl alcohol are shown from the smallest width, at left, to the largest. The colors indicate the thicknesses of the lines, with red representing the greatest thickness. Image courtesy of Brookhaven National Laboratory
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The scientists found that the drop shape deviates from the cylindrical shape of macroscopic drops, typically when the height of each nanodrop is less than 10 nanometers. At these tiny dimensions, the strength of attractive molecule-molecule forces produces an effective change in the surface tension of the liquid. This change, which depends on the thickness of the liquid layer, must be taken into account when determining nanodrops’ shape.

UC Berkeley team develops method for spinning nanofibers

BERKELEY, Calif. - For more than 70 years, scientists have been able to use electric fields to spin polymers into tiny fibers. But there’s been just one problem: Like worms that won’t stop wriggling, the fibers tangle randomly almost as soon as they are created.

Now, researchers at University of California at Berkeley have found a way to use the electric-field process to make nanofibers in a direct, continuous and controllable manner. The technique, known as near-field electrospinning, offers the possibility of producing new, specialized materials with organized patterns that can be used for such applications as wound dressings, filtrations and bio-scaffolds.

Chieh Chang wrote the word “Cal” using a new technique of electrospinning developed at UC Berkeley. The technique makes it possible to arrange nanofibers as small as 50 nanometers in diameter into orderly patterns. Image courtesy of Ron Wilson/UC Berkeley
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Daoheng Sun, a visiting professor of mechanical and electrical engineering from China’s Xiamen University, and Liwei Lin of UC Berkeley developed the new method. Their study appeared in the April issue of the journal Nano Letters. Graduate students Chieh Chang and Sha Li also authored the paper.