Brightsurf Science News and Current Science News Events
 
Email a Friend Send to a friend
Printer Friendly Print Reach out and touch an oscillator: Cornell researchers find a new way to read nanoscale vibrations

Reach out and touch an oscillator: Cornell researchers find a new way to read nanoscale vibrations

March 27, 2007

Nanomechanical oscillators — tiny strips of vibrating silicon only a few hundred atoms thick — are the subject of extensive study by nanotechnology researchers. They could someday replace bulky quartz crystals in electronic circuits or be used to detect and identify bacteria and viruses.

The catch is that measuring their vibrations isn't easy. It is usually done by bouncing laser beams off them — which won't work when the nanodevices become smaller than the wavelength of the light — or with piezoelectric devices — those bulky quartz crystals we're trying to get rid of.




Now Cornell University researchers have come up with a very simple solution: reach out and touch them. The vibration of the tiny oscillators can be measured by "tapping" with an atomic force microscope (AFM).

An AFM uses a tiny probe that moves slowly just above a surface. Electrostatic attraction or repulsion between the atoms in the tip of the probe and those in the surface causes the probe to move up and down, creating an image of the surface so detailed that individual atoms show up as bumps. Alternatively, the AFM can be used in "tapping mode," literally bouncing off the surface.

"AFMs are all over the place," said Rob Ilic, research associate in the Cornell NanoScale Facility and lead author on a paper about the research published Feb. 23 in the online edition of the Journal of Applied Physics. "So this offers a simple way to study these structures." (Cornell, for example, has at least a dozen AFMs in various labs.) Moreover, he said, probes similar to those in an AFM can be built directly into nanofabricated devices.

This would amount to using MEMS to measure NEMS, he said. MEMS (microelectromechanical systems) are machines with moving parts measured in microns, or millionths of a meter; NEMS (nanoelectromechanical systems) are measured in nanometers, or billionths of a meter. A nanometer is about the length of three atoms in a row. When the NEMS oscillator is too small to be observed by laser light, it could still be coupled to a MEMS probe that in turn would be large enough for a laser readout.

To measure the vibration of a nanomechanical oscillator, the AFM probe moves along the length of the oscillating rod. The result is a complex bouncing interaction between the probe and the oscillator — imagine shaking one end of a spring and watching the vibrations at the other end — from which the frequency of vibration of the oscillator can be determined mathematically.

For the experiments just reported, Ilic and colleagues manufactured a wide variety of silicon cantilevers — strips of silicon attached at one end with the other free to vibrate — from 5 to 12 microns long, 1/2 to 1 micron wide and about 250 nanometers thick, which had natural vibration frequencies from 1 to 15 Mhz. The cantilevers were set into vibration by a piezoelectric device.

The experimenters first measured the resonant frequencies of the cantilevers by focusing laser beams on them and observing deflection of the reflected light, then scanned each cantilever with the AFM probe, both in tapping mode and with the probe just above the surface. They found the AFM measurements in good agreement with laser measurements, although the AFM readouts had a somewhat lower "quality factor," because the oscillator and probe were interacting. This would make the method somewhat less precise in mass detection.

Nanomechanical oscillators are often cited as potential tools for detecting bacteria, viruses or other organic molecules. An array of tiny cantilevers might be created with antibodies to many different pathogens attached to them. An experimental solution could then be washed over the array, allowing microbes to bind to the cantilevers with matching antibodies. Since the cantilevers are so tiny, an attached bacterium or virus represents a significant change in mass, which changes the frequency at which the oscillator will vibrate.

In a practical device, a MEMS probe could be mounted above each NEMS oscillator to read out which oscillators in the array show a change in frequency — and thus identify which pathogens are present.

Cornell University



Related Oscillator News Articles Oscillator News and Current Oscillator Events RSS Oscillator News and Current Oscillator Events RSS
A novel X-ray source could be brightest in the world
The future of high-intensity x-ray science has never been brighter now that scientists at U.S. Department of Energy's Argonne National Laboratory have devised a new type of next generation light sources.

Study identifies food-related clock in the brain
In investigating the intricacies of the body's biological rhythms, scientists at Beth Israel Deaconess Medical Center (BIDMC) have discovered the existence of a "food-related clock" which can supersede the "light-based" master clock that serves as the body's primary timekeeper.

Genetic 'tag team' keeps cells on cycle
By surveying the activity of thousands of genes at several different time points, researchers at the Duke Institute for Genome Sciences & Policy have uncovered new evidence that a network of influential genes act as a kind of genetic tag team to orchestrate one of the most fundamental aspects of all life: the cell cycle.

On the Energy Trail: Berkeley Researchers Find New Details Following the Path of Solar Energy During Photosynthesis
Imagine a technology that would not only provide a green and renewable source of electrical energy, but could also help scrub the atmosphere of excessive carbon dioxide resulting from the burning of fossil fuels.

Major physics breakthrough in understanding supersolidity
Physicists at the University of Alberta, in Edmonton, Alberta, Canada, have made a major advance in the understanding of what appears to be a new state of matter.

Simplest circadian clocks operate via orderly phosphate transfers
Researchers at Harvard University and the Howard Hughes Medical Institute have found that a simple circadian clock found in some bacteria operates by the rhythmic addition and subtraction of phosphate groups at two key locations on a single protein.

'Radio wave cooling' offers new twist on laser cooling
Visible and ultraviolet laser light has been used for years to cool trapped atoms-and more recently larger objects-by reducing the extent of their thermal motion.

UCLA engineers set new world record in generation of high-frequency submillimeter waves
Researchers at the UCLA Henry Samueli School of Engineering and Applied Science have achieved a new world record in high-frequency submillimeter waves.

Quantum Secrets of Photosynthesis Revealed
Through photosynthesis, green plants and cyanobacteria are able to transfer sunlight energy to molecular reaction centers for conversion into chemical energy with nearly 100-percent efficiency.

Where is the proton? Yale scientists discover footprints of shared protons
This week in Science, Yale researchers present "roadmaps" showing that shared protons, a common loose link between two biological molecules, simply vibrate between the molecules as a local oscillator, rather than intimately entangling with the molecular vibrations of the attached molecules.
More Oscillator News Articles


Technical Analysis from A to Z, 2nd Edition
by Steven B. Achelis

Millions of traders participating in today’s financial markets have shot interest and involvement in technical analysis to an all-time high. This updated edition of Technical Analysis from A to Z combines a detailed explanation of what technical analysis is and how it works with overviews, interpretations, calculations, and examples of over 135 technical indicators—and how they...



Technical Analysis for the Trading Professional
by Constance Brown

"There are fifteen major breakthroughs in technical analysis! SEVEN of these breakthroughs are new, never-before-revealed material!" - George Lane, Stochastics Originator. As professional traders approach the 21st century, accelerating technological change threatens to make conventional technical studies and indicators ineffective. To compete in this changing environment, these professionals need...



The Complete RSI Book
by John Hayden

Learn how to effectively use RSI, a mainstream technical indicator which is in virtually every technical analysis software package. Properly understood and utilized, it can be a powerful tool to help you time and select trades. This book is an informative guide to the use and interpretation of RSI. Table of Contents: Section I Preparation and Understanding The Key to Success! 1. Overview 2. RSI...



The Design of Modern Microwave Oscillators for Wireless Applications : Theory and Optimization
by Ulrich L. Rohde, Ajay K. Poddar, Georg Böck

Delivering the best possible solution for phase noise and output power efficiency in oscillators This complete and thorough analysis of microwave oscillators investigates all aspects of design, with particular emphasis on operating conditions, choice of resonators and transistors, phase noise, and output power. It covers both bipolar transistors and FETs. Following the authors' guidance,...



RF and Microwave Transistor Oscillator Design
by Andrei Grebennikov

The increase of consumer electronics and communications applications using Radio Frequency (RF) and microwave circuits has implications for oscillator design. Applications working at higher frequencies and using novel technologies have led to a demand for more robust circuits with higher performance and functionality, but decreased costs, size and power consumption. As a result, there is also a...



The Designer's Guide to High-Purity Oscillators (The Designer's Guide Book Series)
by Emad Hegazi, Jacob Rael, Asad Abidi

The Designer's Guide to High-Purity Oscillators presents a comprehensive theory and design methodology for the design of LC CMOS oscillators used in every wireless transmission system. The authors introduce the subject of phase noise and oscillators from the very first principles, and carry the reader to a very intuitive circuit-driven theory of phase noise in LC oscillators. The theory presented...



Complete Wireless Design
by Cotter W. Sayre

Easily design today’s wireless systems and circuits Design an entire radio system from the ground up instead of relying on a simple plug-in selection of circuits to be modified. Avoid an arduous trek through theory and mathematical derivations. Cotter Sayre’s Complete Wireless Design covers wireless hardware design more thoroughly than any other handbook —and does it without...



Modeling and Characterization of RF and Microwave Power FETs (The Cambridge RF and Microwave Engineering Series)
by Peter Aaen, Jaime A. Plá, John Wood

This is a book about the compact modeling of RF power FETs. In it, you will find descriptions of characterization and measurement techniques, analysis methods, and the simulator implementation, model verification and validation procedures that are needed to produce a transistor model that can be used with confidence by the circuit designer. Written by semiconductor industry professionals with...

The power of oscillator/cycle combinations: How to combine oscillator and cycle analysis to improve market timing and profits in the futures markets
by Walter J Bressert

Lakhovsky Multiple Wave Oscillator Handbook: Comprising the Borderland Sciences Research Foundation Lakhovsky Multiple Wave Oscillator & Radio-Cellular Oscillator Research Files

© 2008 BrightSurf.com