TechBlog

A schematic of graphene nanoribbon field-effect transistor with palladium contacts (S,D) on a 10 nm thick insulating silicon dioxide surface (purple). Beneath the Si02 layer is a highly conductive silicon layer (G). Credit: Stanford University.

Stanford chemists have developed a new way to make transistors out of carbon nanoribbons. The devices could someday be integrated into high-performance computer chips to increase their speed and generate less heat, which can damage today’s silicon-based chips when transistors are packed together tightly.

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Engineers and applied physicists from Harvard University have demonstrated the first room-temperature electrically-pumped semiconductor source of coherent Terahertz (THz) radiation, also known as T-rays. The breakthrough in laser technology, based upon commercially available nanotechnology, has the potential to become a standard Terahertz source to support applications ranging from security screening to chemical sensing.Spearheaded by research associate Mikhail Belkin and Federico Capasso, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering, both of Harvard’s School of Engineering and Applied Sciences (SEAS), the findings will be published in the May 19 issue of Applied Physics Letters. The researchers have also filed for U.S. patents covering the novel device.

Using lasers in the Terahertz spectral range, which covers wavelengths from 30 to 300å, has long presented a major hurdle to engineers. In particular, making electrically pumped room-temperature and thermoelectrically-cooled Terahertz semiconductor lasers has been a major challenge. These devices require cryogenic cooling, greatly limiting their use in everyday applications.

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r. Yu-Chong Tai, professor of electrical engineering and bioengineering at the California Institute of Technology in Pasadena, is an electrical engineer whose early work pioneered a new direction that is now called, “microelectromechanical systems” (MEMS). He has published on just about every facet of MEMS, from shear-stress sensors to micromachining to thermal sensors to lab-on-a-chip. His recent research forays are leading him into studies of biological systems at the micro level. According to our Special Topics analysis of MEMS research over the past decade, Dr. Tai’s work ranks at #5, with 27 qualifying papers cited a total of 272 times. In the ISI Essential Science Indicators Web product, Dr. Tai’s record includes 41 papers cited a total of 383 times to date. Dr. Tai points to some of his earlier papers and presentations, which are outside of the range of our database, as very important in the field. Among these is a presentation report (Fan L.S., Tai Y.C., Muller R.S., “IC-processed electrostatic micromotors,” Tech. Digest, IEEE International Electron Device Meeting [IEDM ’88], San Francisco, Calif., Dec. 11-14, 1988, pp.666-669; and Fan L.S., Tai Y.C., Muller R.S., “Integrated movable micromechanical structures for sensors and actuators,” IEEE Trans. On Electron Devices ED-35:724-730, 1988). Dr. Tai is a graduate of National Taiwan University and received his master’s and Ph.D. in electrical engineering and computer sciences from University of California, Berkeley. He took a faculty appoint at the California Institute of Technology in 1989.

Your work is in microelectromechanical systems (MEMS). Could you explain what this field is?

The name MEMS didn’t even exist in the ‘80s while I was in graduate school. My major was integrated circuits (IC) then. I learned solid-state devices and IC technology. So I know how to make these devices. It all started with an interesting question. We knew that the IC industry was really big in the 1980s. People had already invested billions, if not trillions, of dollars in IC technology. The question was: can we do something with the IC technology for applications other than IC? In other words, IC technology is a huge investment, could something else benefit from it? Here, IC is really only electrical devices. What devices, other than electrical devices, could we build? From an academic point of view, this whole world is either electrical or mechanical. For example, even biology and its fundamental science are all electrical or mechanical. Similarly, chemistry is no different.

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Scientists have discovered a way of speeding up the production of hollow-core optical fibers — a new generation of optical fibers that could lead to faster and more powerful computing and telecommunications technologies.

The procedure, described in the journal Optics Express, cuts the production time of hollow-core optical fibers from around a week to a single day, reducing the overall cost of fabrication.

Initial tests show that the fiber is also superior in virtually every respect to previous versions of the technology, making it an important step in the development of new technologies that use light instead of electrical circuits to carry information.

These technologies include faster optical telecommunications, more powerful and accurate laser machining, and the cheaper generation of x-ray or ultra-violet light for use in biomedical and surgical optics.

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A national team of scientists led by experts at Durham University are embarking on one of the UK’s largest ever research projects into photovoltaic (PV) solar energy.

The £6.3million PV-21 programme will focus on making thin-film light absorbing cells for solar panels from sustainable and affordable materials.

The four-year project, which begins in April (2008), is being funded by the Engineering and Physical Sciences Research Council (EPSRC) under the SUPERGEN initiative.

Eight UK universities, led by Durham and including Bangor, Bath, Cranfield, Edinburgh, Imperial College London, Northumbria and Southampton, are involved in the project.

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Scientists at Arizona State University’s Biodesign Institute have developed the world’s first gene detection platform made up entirely from self-assembled DNA nanostructures. The results, appearing in the January 11 issue of the journal Science, could have broad implications for gene chip technology and may also revolutionize the way in which gene expression is analyzed in a single cell.

“We are starting with the most well-known structure in biology, DNA, and applying it as a nano-scale building material, ” said Hao Yan, a member of the institute’s Center for Single Molecule Biophysics and an assistant professor of chemistry and biochemistry in the College of Liberal and Sciences.

Yan is a researcher in the fast-moving field known as structural DNA nanotechnology — that assembles the molecule of life into a variety of nanostructures with a broad range of applications from human health to nanoelectronics.

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Photonic crystal fiber’s ability to create broad spectra of light, which will be the basis for important developments in technology, has been explained for the first time in an article in the leading science journal Nature-Photonics.The fiber can change a pulse of light with a narrow range of wavelengths into a spectrum hundreds of times broader and ranging from visible light to the infra-red. This is called a supercontinuum.

This supercontinuum is one of the most exciting areas of applied physics today and the ability to create it easily will have a significant effect on technology.

This includes telecommunications, where optical systems hundreds of times more efficient than existing types will be created because signals can be transmitted and processed at many wavelengths simultaneously.

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1.0 Introduction

Essentially, wave/particle duality employs the notion that an entity simultaneously possesses localized (particle) and distributed (wave) properties.The idea has been introduced into modern physics to account for observations in which particles of matter interact to produce effects that appear to be identical to the effects that occur when waves diffract and interfere.

However, the concept rests on an assumption. It is assumed that wave propagation mechanisms can provide the only possible explanation for scattering effects observed in experiments such as the Twin Slit experiment.

At face value, the assumption looks convincing. The French physicist, Louis de Broglie introduced the wave/particle concept into physics in the 1920s, with a brilliant prediction that particles of matter possess wave properties and act as though they were composed of propagating waves. Experimental confirmation of de Broglie’s prediction (electron diffraction in crystals) has led to the theory being cemented into the foundations of modern physics.

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