Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers develop bistable nanoswitch

17.10.2006
Carbon nanotubes (CNT) have been under intense study by scientists all over the world for more than a decade and are being thought of as ideal building blocks for nanoelectromechanical systems (NEMS).

A type of one-dimensional structure with high-aspect ratio, carbon nanotubes have emerged as a promising material because of their many impressive mechanical, electrical and chemical properties.

Now scientists from Northwestern University have demonstrated a novel carbon nanotube-based nanoelectromechanical switch exhibiting bistability based on current tunneling. The device could help advance technological developments in memory chips and electronic sensing devices.

The research is published online by the scientific journal Small.

"We believe the unique characteristics of this nano device will likely lead to many high-impact applications in the field of nanoelectronics and nanosensors," said Horacio Espinosa, professor of mechanical engineering in the McCormick School of Engineering and Applied Science. Espinosa and Changhong Ke, a former graduate student of Espinosa's, co-authored the paper.

Since the invention of the integrated circuit (IC), the semiconductor industry has boomed following the famous Moore's law. However, as the characteristic dimension achievable by various photolithography techniques approaches its physical limits, scientists are searching for new materials and new device concepts to be able to continue the large-scale integration trend.

"Although several carbon nanotube-based NEMS devices have been proposed, frankly, none of them has reached the level of commercial success," said Espinosa. "There are many challenges associated with nanofabrication and reliability."

Nanoscale manufacturing is complex and too expensive, imposing significant challenges to the design of nano devices. Assessing device reliability based on nanoscale experimentation is one big challenge. For example, placement of nano-objects at desired locations is difficult and lacks reproducibility. Likewise, real-time observation and characterization of mechanical motion requires the use of in-situ electron microscopy and electronic measurement techniques capable of controlling noise and parasitic effects.

Espinosa and his team solved some of these issues by designing and demonstrating a tunneling bistable switch. The device is made of a free suspended multiwalled carbon nanotube interacting electrostatically with an underlying electrode. In the device circuit, there is a resistor in series with the nanotube, which plays an important role in the functioning of the device by adjusting the voltage drop between the nanotube and the underlying electrode.

"The design of the device looks very simple, but the theories behind it are very complex and span several disciplines, including quantum mechanics, electronics and mechanics," said co-inventor Ke, now a post-doctoral fellow at Duke University. "Also, a major advantage of our device is its geometry, which is fully compatible with current manufacturing techniques for mass production."

Espinosa and Ke demonstrated the behaviors of the device by mounting individual carbon nanotubes to the tip of a tungsten probe using a nanomanipualtor inside a scanning electron microscope. Then the nanotube was actuated by applying a potential to an adjustable micron-size gap between the nanotube and an electrode. The motion of the nanotube was recorded by the electron microscope, and the current in the circuit was recorded by a source-measurement unit.

Northwestern has filed a patent application covering the concept of the bistable tunneling device and its application and is seeking commercial partners to develop the technology. The potential applications of the device include NEMS switches, random-access memory elements and logic devices.

Megan Fellman | EurekAlert!
Further information:
http://www.northwestern.edu

More articles from Materials Sciences:

nachricht Breakthrough in nanoresearch - Quantum chains in graphene nanoribbons
09.08.2018 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt

nachricht UNH Researchers find seed coats could lead to strong, tough, yet flexible materials
08.08.2018 | University of New Hampshire

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

Im Focus: World record: Fastest 3-D tomographic images at BESSY II

The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.

Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

'Building up' stretchable electronics to be as multipurpose as your smartphone

14.08.2018 | Information Technology

During HIV infection, antibody can block B cells from fighting pathogens

14.08.2018 | Life Sciences

First study on physical properties of giant cancer cells may inform new treatments

14.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>