The American offices of Kapsch are reporting “extraordinary success” in a performance evaluation of their 5.9GHz electronic toll system in trials on E470 in Colorado recently. In a press statement they say a nationally known, independent R&D laboratory evaluated the system and determined that it collected “100%” of more than 10,500 DSRC sample passes. Read more…

Microscopic evolution

Elaine Mulcahy

Advances in microscopy and measurement techniques drive scientific progress. From Galileo Galilei to Binnig and Rohrer, NANO takes a look at the evolution of microscopes to the recent news of a scope capable of seeing atoms on the pico scale.

400 years have passed since Galileo demonstrated the first use of his telescope for observing stars in the sky, which soon after led to the discovery of Jupiter’s moons. Galileo was also instrumental in developing the first compound microscopes, which he used to investigate the intricate details of an insect’s limbs.

Today, microscopes have reached the planets that Galileo viewed through his telescope and are relaying images from the far reaches of the solar system back to Earth.

The optical, or light, microscope is the oldest and simplest microscope and continues to play an important role in scientific investigation. Optical microscopes are based on the principle of refraction, whereby light bends as it passes through a system of lenses, in much the same way as light passing through the lens in the eye forms an image on the retina. Compound microscopes use many lenses to magnify the image.

Compound microscopes are capable of magnifying an image up to 1000 times however, there comes a point when diffraction, a natural phenomenon whereby light tends to bend around corners, forces limitations on the resolution. At high resolutions, images viewed through an optical microscope are surrounded by diffraction rings, so called Airy disks, making it impossible to resolve the fine details of the object.

The transmission electron microscope, developed in 1931 by Ernst Ruska and Max Knoll at the Technical University of Berlin, was the first microscope to overcome the limitations of optical microscopy by using electrons rather than light to create images. Like light, electrons behave in waves and interact as they are passed through a specimen to create an image. Modern TEMs are capable of magnifications up to 50 million times – on a scale 0.1 nanometres. However, the TEM is limited by the extensive preparation that is required before a specimen can be imaged. The sample must be extremely thin, for example, for the electrons to pass through it to create the image. Ernst Ruska was awarded half of the 1986 Nobel Prize for Physics for his fundamental work in electron optics, and for the design of the first transmission electron microscope.

The scanning electron microscope also uses electrons to create an image. In this case, rather than “seeing” the object to create an image, the electrons “feel” the object and create an image based on a scan of the surface. A high-energy beam of electrons is scanned across the surface of the object and returns a detailed topography which is then translated into an image.

The SEM is capable of producing very high-resolution images, revealing details just one nanometre in size, in three dimensions. Magnification with the SEM ranges from about x 25 to x 250,000. The first SEM image was obtained by Max Knoll in 1935.

The scanning tunnelling microscope was invented by Gerd Binnig and Heinrich Rohrer at IBM Zurich in 1981 and the pair were awarded the second half of the 1986 Nobel Prize for Physics for the invention. The STM was the first microscope capable of viewing surfaces at the atomic level and a resolution of 0.1 to 0.01 nanometres.

Operation of the STM is based on the concept of quantum tunnelling whereby a conducting tip brought very close to a metallic or conducting surface allows electrons to tunnel through the vacuum between them. Variations in current as the tip passes over the surface are translated into an image – the microscope essentially draws a copy of the image based on the structure felt on the surface. STM requires extremely clean surfaces and sharp tips.

The STM has formed the basis for a range of microscopy techniques, such as photon scanning tunnelling microscopy, and has been used in microfabrication techniques and lithography.

The Atomic Force Microscope is the daughter of the STM. It was developed by Binnig, Quate and Gerber in 1986, the same year that Ruska, Binnig and Rohrer were awarded the Nobel Prize. The AFM is today one of the foremost tools for imaging, measuring and manipulating matter at the nanoscale.

The AFM works when a tiny tip at the end of a cantilever is brought into contact with a sample. Atomic forces between the tip and the sample surface cause small deflections in the cantilever, which are measured by the AFM and used to create an image. The AFM can operate in a number of different modes ranging from static to dynamic and has been used to image and manipulate atoms and structures on a variety of surfaces.

A major advantage of the AFM is its small size. On board the Phoenix Lander currently on the surface of Mars, an AFM the size of a matchbox and weighing just 15g is relaying images back to Earth.

Transmission electron microscopes equipped with state-of-the-art corrector units allowing for a minimisation of lens aberrations recently entered the picometer scale. A team from Forschungszentrum Julich, a member of the Helmholtz Association, led by Professor Urban Knut, recently reported in Science (25 July) of the first precise measurements of atomic displacements down to a few picometres using new methods in ultrahigh-resolution transmission electron microscopy.

A picometre is equal to one billionth of a millimetre, a distance that is one hundred times smaller than the diameter of an atom.

The Julich scientists were able to determine the exact position of atoms in the boundary between two areas of a high-temperature superconductor, by calculating the quantum mechanical wave function of electrons from microscopic images taken under dedicated imaging conditions. Their finding, that relatively heavy atoms of barium, copper and yttrium were systematically displaced a few picometres from their ideal position in the boundary, could help to explain the attenuation of superconducting properties when electric current flows over the boundary. Moreover, local polarisation phenomena in a ferroelectric material could studied by characteristic shifts of atoms, which induce charge-dipole formation by lowering the local symmetry of the crystal.

The researchers state that displacements of a few picometres have an impact on a whole number of physical properties. To be able to measure them atom by atom for the first time could lead to new discoveries in technology.

Urban says, “This is the beginning of a new physics of materials which enables researchers to determine physical parameters and properties in the nano range through highly precise measurements of the atomic spacings. This will also provide clues on how these properties may be manipulated to gain new functions and better functional performance.”

Imaging at such tiny scales enables exploration of biological and physical systems at unimaginable depths and, as imaging technologies continue to advance, so too does understanding and technological progress across all branches of science.

Brewer Science, a trusted, long-term provider of leading edge materials and processes to the semiconductor industry announces the commercial availability of the first microelectronic-grade carbon nanotube coating. A break-through in the refinement of the carbon nanotube material enables the removal of metallic and carbonaceous contaminants. The coating is easily applied by spin, spray, micro-dispensing or ink-jet printing.

Qualities

    * Industry standard cleanliness for trace metals
    * Low carbonaceous impurities
    * Individual/unbundled CNTs in surfactant-free benign solvent
    * Stable suspension of individual carbon nanotubes
    * Trusted semiconductor materials manufacturer
    * Processed by CMOS industry fabrication and diagnostic tools

Applications

    * NRAM™ *, Non-volatile, highly scalable, fast memory for stand-alone, embedded, or application specific designs
    * Logic
    * Bio-sensor, Chemical detection sensor and IR detector applications
    * Wide verities of applications in the area of Display, printing circuit etc.

* Brewer Science, Inc., under a technology license from Nantero, Inc., is the exclusive manufacturer & supplier of microelectronics-grade CNT coating for NRAM field of uses.

June 24, 2008 — Kebaili Corporation a high-tech MEMS and nanotechnology company, has released the KMHP-100 Series, the industry’s first commercially available off-the-shelf MEMS microhotplates for researchers and scientists in innovative chemical sensor research and development applications.

KMHP-100 MEMS microhotplate consists of a micromachined silicon die attached to a gold-plated TO-18 package, which insures reliable and stable continuous operation in harsh and hostile environment applications. The platinum resistive thin-film microheater sandwiched between freestanding thin-film silicon nitride and silicon dioxide membranes allows the microhotplate to operate continuously and reliably at temperatures up to 650 degrees C. The freestanding thin-film silicon nitride membrane thermally and electrically isolates the platinum microheater from the silicon substrate microstructure, and provides the microhotplate with a low thermal mass. The KMHP-100 MEMS silicon chip is based on Kebaili Corporation’s proprietary 1mm x 1mm microchip die size MEMS microsensor platform technology.
Kebaili Corporation KMHP-100 microhotplates will allow researchers and scientists to develop innovative and ultra-highly sensitive and selective chemical sensors based on MEMS, nanotechnology, sol-gel processes, doped metal oxides, polymers, functionalized carbon nanotubes and nanowires. These novel chemical microsensors will be used in medical, industrial, military, automotive, environmental, agricultural, space and homeland security applications.
By using off-the-shelf KMHP-100 microhotplates, scientists doing research and development work on novel chemical microsensors based on MEMS microhotplate platform, can significantly reduce their development cost, and lower their development time from several weeks to only few days or few hours depending on their process and target application.

AIST developed a technology to fabricate a high-concentration SWCNT and used it in the production of transistor. First, powders of commercially available SWCNT material were dispersed in a solution by using polyfluorene (PFO), which is a conjugated polymer, as a dispersing agent.<!–more–> Then, the mixed dispersion solution was separated by using an ultracentrifuge at a rotation of 30,000rpm or faster so that the supernatant solution of semiconductor SWCNT thus separated was selectively extracted.
After removing PFO, a semiconductor SWCNT film was formed by coating a substrate with the semiconductor SWCNT solution.
A transistor using a SWCNT thin film is less expensive, superior in mass productivity and highly suitable for a larger surface area. Transistor performance degrades significantly, however, if a metal SWCNT other than the semiconductor SWCNT or even a small amount of a metallic impurity gets mixed in. As a result, there has been strong demand for the development of a technology for separating and extracting high-purity semiconductor SWCNT, according to AIST.
In order to obtain a high-quality semiconductor SWCNT thin film, ultracentrifugal separation was conducted for 60 minutes. As a result, a metal SWCNT and other impurities were removed so that their remaining amount became less than the detection limit. PFO remaining in the semiconductor SWCNT dispersion solution after ultracentrifugal separation was also removed, according to AIST. Then, filtration, cleansing and heating treatment were carried out.
Moreover, AIST reportedly evaluated the preferable conditions for film thickness reduction based on spin coating, etc.
To improve the transistor characteristics, a technique called “dielectrophoresis” was used for thin film formation so that SWCNTs facing in different directions were oriented in one direction simultaneously with the reduction of film thickness. Specifically, the semiconductor SWCNT dispersion solution was dropped on an electrode pair prepared in advance, and the solvent was evaporated while applying the alternating electric field between the electrodes, AIST said.
With this technique, the SWCNTs were concentrated between the electrodes, while at the same time they were oriented in the direction of the electric field, according to AIST.

One of the instruments on board the Phoenix Mars Mission is a Swiss atomic force microscope designed to investigate Martian soil samples for possible traces of ice. This nano-microscope is the fruit of scientific collaboration of the Institute of Microtechnology at the University of Neuchâtel, the Institute of Physics at the University of Basel, and Nanosurf AG in Liestal. The goal of the Phoenix Mission is to answer important questions such as whether water exists in forms that support life. All onboard instruments are checked for functionality during the first few days after a successful landing, following which the first measurement data will be transmitted to earth.

Researchers at North Carolina State University have created a substance far stronger and harder than conventional iron, and which retains these properties under extremely high temperatures, opening the door to a wide variety of potential applications, such as engine components that are exposed to high stress and high temperatures. Iron that is made up of nanoscale crystals is far stronger and harder than its traditional counterpart, but the benefits of this “nano-iron” have been limited by the fact that its nanocrystalline structure breaks down at relatively modest temperatures. But the NC State researchers have developed an iron-zirconium alloy that retains its nanocrystalline structures at temperatures above 1 300 degrees Celsius, approaching the melting point of iron. The alloy’s ability to retain its nanocrystalline structure under high temperatures will allow for the material to be developed in bulk, because conventional methods of materials manuf! acture rely on heat and pressure, said the scientists. The ability to work with the material at high temperatures will make it easier to form the alloy into useful shapes – for use as tools or in structural applications, such as engine parts, they added.