Metamaterials Could Reduce Mechanical Friction in Nanotechnology

Nanoscale machines expected to have wide application in industry, energy, medicine and other fields may someday operate far more efficiently thanks to important theoretical discoveries concerning the manipulation of famous Casimir forces that took place at the U.S. Department of Energy’s Ames Laboratory.

The groundbreaking research, conducted through mathematical simulations, revealed the possibility of a new class of materials able to exert a repulsive force when they are placed in extremely close proximity to each other.  The repulsive force, which harnesses a quantum phenomenon known as the Casimir effect, may someday allow nanoscale machines to overcome mechanical friction.

Though the frictional forces in nanoscale environments are small, they significantly inhibit the function of the tiny devices designed to operate in that realm, explained Costas Soukoulis, a senior physicist at the Ames Lab and Distinguished Professor of physics at Iowa State University, who led the research effort.

Soukoulis and his teammates, including Ames Laboratory assistant scientist Thomas Koschny, were the first to study the use of exotic materials known as chiral metamaterials as a way to harness the Casimir effect.  Their efforts have demonstrated that it is indeed possible to manipulate the Casimir force.  The findings were published in the Sept. 4, 2009 issue of Physical Review Letters, in an article entitled, “Repulsive Casimir Force in Chiral Metamaterials.”

Understanding the importance of their discovery requires a basic understanding of both the Casimir effect and the unique nature of chiral metamaterials.

The Casimir effect was named after Dutch physicist Hendrik Casimir, who postulated its existence in 1948.  Using quantum theory, Casimir predicted that energy should exist even in a vacuum, which can give rise to forces acting on the bodies brought into close proximity of each other.  For the simple case of two parallel plates, he postulated that the energy density inside the gap should decrease as the size of the gap decreases, also meaning work must be done to pull the plates apart.  Alternatively, an attractive force that pushes the plates closer together can be said to exist.

Casimir forces observed experimentally in nature have almost always been attractive and have rendered nanoscale and microscale machines inoperable by causing their moving parts to permanently stick together.  This has been a long-standing problem that scientists working on such devices have struggled to overcome.

Remarkably, this new discovery demonstrates that a repulsive Casimir effect is possible using chiral metamaterials.  Chiral materials share an interesting characteristic:  their molecular structure prevents them from being superimposed over a reverse copy of themselves, in the same way a human hand cannot fit perfectly atop a reverse image of itself.  Chiral materials are fairly common in nature.  The sugar molecule (sucrose) is one example.  However, natural chiral materials are incapable of producing a repulsive Casimir effect that is strong enough to be of practical use.

For that reason, the group turned its attention to chiral metamaterials, so named because they do not exist in nature and must instead be made in the lab.  The fact that they are artificial gives them a unique advantage, commented Koschny.  “With natural materials you have to take what nature gives you; with metamaterials, you can create a material to exactly meet your requirements,” he said.

 The chiral metamaterials the researchers focused on have a unique geometric structure that enabled them to change the nature of energy waves, such as those located in the gap between the two closely positioned plates, causing those waves to exert a repulsive Casimir force.

The present study was carried out using mathematical simulations because of the difficulties involved in fabricating these materials with semiconductor lithographic techniques.  While more work needs to be done to determine if chiral materials can induce a repulsive Casimir force strong enough to overcome friction in nanoscale devices, practical applications of the Casimir effect are already under close study at other DOE facilities, including  Los Alamos and Sandia national laboratories.  Both have expressed considerable interest in using the chiral metamaterials designed at Ames Laboratory to fabricate new structures and reduce the attractive Casimir force, and possibly to obtain a repulsive Casimir force.

Funding for this research was provided by the DOE Office of Science.

CO2 Solution Reveals Enzymatic Process for Recycling Power Plant CO2 Emissions

CO2 Solution Inc. (Quebec, Canada) received United States patent, 7,596,952 for a process and a plant for recycling carbon dioxide emissions from power plants into useful carbonated species. The patent provides for exclusivity in the field of using the enzyme carbonic anhydrase, or an analog thereof, for the capture of CO2 from any fossil power plant, where captured CO2 is converted into a carbonated species. The company believes that the patent has potentially significant value for efficient carbon capture in coal and other fossil fuel power plants.

The process for recycling carbon dioxide emissions from a fossil-fuel power plant into useful carbonated species primarily consists  of the steps: a) combustion of a fossil fuel, thereby generating heat and a hot exhaust gas containing CO2 and b) converting the heat into energy. The process is characterized in that it further comprises the steps of: c) cooling the exhaust gas; and d) biologically transforming at least a portion of the CO2 contained in the cooled exhaust gas into carbonated species, thereby obtaining a low CO2 exhaust gas and producing useful carbonated species. The low CO2 exhaust gas obtained in step d) can be released in the atmosphere without increasing the problem of greenhouse effect.

This patent is the fourth new patent received by CO2 Solution during 2009, in addition to the following:

U.S. Patent 7,514,056 ‐ Process and installation for the fractionation of air into specific gases; Protects the use of carbonic anhydrase for use in efficiently capturing CO2 from compressed air as part of an air‐separation unit for the production of oxygen. The Company believes that the patent can address the cost challenge that conventional air‐separation processes face due to ever increasing CO2 concentrations in ambient air. The specialty gas industry has shown interest in the patent and CO2 Solution intends to pursue possible commercialization opportunities therein.

U.S. Patent 7,521,217 ‐ Carbonic anhydrase having increased stability under high temperature conditions; Covers the Company’s proprietary enzyme ‘mutants’ which have increased thermal and industrial stability through genetic engineering.

Canadian Patent 2,443,222 ‐ A process and plant for the production of Portland cement clinker (equivalent U.S. Patent 6,908,507); Covers the use of the enzyme for the capture of CO2 from cement plant flue gas and the production of calcium carbonate for reuse in the cement making process, and has the potential to materially reduce overall carbon emissions from the cement production process.

Regarding the issuance of these four new patents, Mr. Glenn Kelly, President & CEO stated: “These patents build on our already broad intellectual property portfolio in enzymatic carbon capture, at a time when industry is increasingly searching for new ways to capture CO2 that are more efficient than conventional scrubbing technology. There has recently been heightened interest in the use of carbonic anhydrase in this context. As such, we believe these patents further solidify CO2 Solution’s technology leadership position in the field, and in the rapidly growing carbon capture space.”

Marine Carbon Nanotube Epoxy Coatings Cut Ship Fuel Consumption by 10%

The Norwegian company Advanced Marine Coatings based in Gamle Fredrikstad specializes in the development of environmentally compatible, heavy-duty anti-corrosion coatings for sea-going vessels is the first company to apply  The “Green Ocean Coating Heavy Duty” coatings which are formulated with Baytubes® carbon nanotubes (CNT) from Bayer MaterialScience. The coating give the ships with them very high abrasion resistance. The coatings also reduce the flow resistance between the ship's hull and the water, thereby enabling a significant reduction in fuel consumption and carbon dioxide (CO2) emissions.

“According to our knowledge, this is the first application of Baytubes® carbon nanotubes in marine coatings”, says Dr. Raul Pires, head of Global Activities for Nanotubes and Nanotechnology Products at Bayer MaterialScience. The coatings are suitable for both new vessels and for subsequent repair and maintenance coatings and reduce fuel consumption by as much as 10%.

The Berge Arzew with “Green Ocean Coating Heavy Duty” Coatings

Photo Credit: Bayer MaterialSceince: The “Green Ocean Coating Heavy Duty” coatings from Advanced Marine Coatings are formulated with Baytubes® carbon nanotubes from Bayer MaterialScience, which gives them very high abrasion resistance. The coatings also reduce the flow resistance between the ship's hull and the water, thereby enabling a significant reduction in fuel consumption that if adopted worldwide could reduce CO2 emissions by 70 million tons.

The Green Ocean Coating Heavy Duty systems are two-component epoxy mastic resins coatings with extremely high resistance to water, making them particularly suitable for marine coatings and in particular for the part of the hull below the surface of the water. Thanks to the addition of Baytubes® carbon nanotubes, these have a very smooth surface and thus help to save fuel and reduce carbon dioxide emissions.

Another major advantage is the reduction of maintenance costs. The ban on organic tin compounds for use as antifouling agents to prevent organic growth has necessitated relative frequent cleaning of the coating surface on the ship’s hull to ensure cost-effective transport. “We hope that the smoothness and greater hardness of the coating will provide better durability and will allow us to extend the cleaning cycle. Thanks to the use of Baytubes®, the systems represent both the most ecological and the most economic solution,” says Stein Dietrichson, Managing Director of Advanced Marine Coatings.

The first ship to be coated with this system was the Berge Arzew, an LNG (liquified natural gas) tanker with a capacity of 138,000 cubic meters. Extensive test coatings of a Green Ocean Coating were successfully applied to a surface area of 700 square meters. The VOC-free system (VOC stands for volatile organic compounds) was applied in film thicknesses of up to 400 micrometers. “The results so far are highly promising. The nanotubes evidently make for a very smooth, pore-free surface,” says Dietrichson.

A film shot in spring 2007 at NTNU and SINTEF Marintek in Trondheim, shows the AMC R & D manager, Eng. Paal Skybak,  who explains about nano modified paints and the Green Ocean development program.
The film is focused on the environment with much attention on CO₂ emissions and how sleek coatings enable energy savings of up to 10%. The consequences of this on a global basis could be a total reduction in CO₂ emissions of more than 70 million tons. This was explained by a Bellona representative, who also said that this will be an important contribution to the effort to improve the global climate by reducing CO2 emissions.
The program may be seen by following this link to: Paint can make ships more environmentally friendly

Lockheed Martin Tests Carbon Nanotube-Based Memory Devices on NASA Shuttle Mission

A radiation-resistant version of NRAM(TM) carbon-nanotube-based memory, developed jointly by Lockheed Martin (NYSE: LMT) and Nantero, was tested on a recent Space Shuttle mission. The NRAM(TM) was incorporated by NASA into special autonomous testing configurations installed into a carrier at the aft end of the payload bay. It was launched into space as part of STS-125, the May 2009 mission of the Space Shuttle Atlantis that successfully serviced the Hubble Space Telescope. The project was managed by Dan Powell, Chief Nanotechnologist at NASA Goddard Space Flight Center (GSFC).

"Lockheed Martin is a leader in the research, development and application of nanotechnology to future government applications," said Dr. Jim Ryder, vice president and general manager of the Lockheed Martin Advanced Technology Center in Palo Alto. "This demonstration of carbon-nanotube-based semiconductor devices in the rigorous conditions of space is an important step towards a whole new suite of future applications."

The experiment was a proof-of-concept that enabled the testing of launch and re-entry survivability, as well as basic functionality of the carbon nanotube switches on orbit throughout the shuttle mission. The NRAM(TM) devices were early prototype parts, and performed the same before, during, and after completion of the mission. This mission represents an important first step in the development of high-density, non-volatile, carbon-nanotube-based memories for spaceflight applications. Lockheed Martin and NASA are working on plans for future NRAM(TM) flights.

Carbon nanotubes are tiny cylindrical carbon molecules just 1/50,000th the diameter of a human hair that possess unique electrical and structural properties. The word nanotube is, of course, from nanometer (10-9 meters or approximately 10 carbon atoms) and tubular (the shape of a rolled up sheet of graphene that forms a carbon nanotube). Carbon nanotubes are half the density of aluminum, 50 times stronger than steel, thermally stable in vacuum up to nearly 3,000 degrees Centigrade, efficient conductors of heat and may be either metallic or direct bandgap semiconductors.

Thomas Rueckes, Nantero's Co-founder and CTO, said, "We are proud of the success of our NRAM memory devices in even the harshest of conditions, and honored for being selected by NASA for this mission."

Dan Powell of GSFC, said "Carbon nanotubes have tremendous potential for a wide range of future space-based applications, and we couldn't be happier for the success of this experiment."

Lockheed Martin recognizes the critical importance of nanotechnology to its current and future portfolio of products and services. Direct benefits of nanotechnology for government customers could include stronger, lighter and less expensive materials; more capable systems; and enhanced personal protection for military and first responders. Through partnerships with small businesses and universities, Lockheed Martin is leveraging its own investment in nanotechnology to develop innovative solutions for the most demanding technological challenges. Lockheed Martin Nanosystems is a business unit of Lockheed Martin Space Systems Company.

Nantero is a nanotechnology company using carbon nanotubes for the development of next-generation semiconductor devices. Nantero's main focus is the development of NRAM(TM). Nantero is also working with licensees on the development of additional applications of Nantero's core nanotube-based technology. Lockheed Martin holds an exclusive license arrangement with Nantero for government applications of Nantero's extensive intellectual property portfolio. More information on Nantero, Inc. is available in English and Japanese at http://www.nantero.com.

Headquartered in Bethesda, Md., Lockheed Martin is a global security company that employs about 140,000 people worldwide and is principally engaged in the research, design, development, manufacture, integration and sustainment of advanced technology systems, products and services. The corporation reported 2008 sales of $42.7 billion.

Palm Sized Superfine Inkjet Prints Micro Circuits Using Harima NanoPaste

The practical and widespread implementation of nanotechnology requires precise three-dimensional arrangement of functional materials. There is significant demand for an inkjet printer that can print structures with complex topologies. To meet this demand Japan’s National Institute of Advanced Industrial Science and Technology (AIST) has successfully developed a super-fine inkjet printer, which can discharge micro ink droplets, far smaller than those of normal inkjet printers. To allow widespread use of this  technology, AIST has designed a portable unit that is about 600 times smaller than the first generation SIJ printer and fits in the palm of a hand.  By using this ultra-small SIJ units, micrometer scale patterning or precise material deposition in the femtoliter order is feasible. Mask-less patterning, such as micrometer scale circuit pattern can be achieved without the photolithographic process.

 Photo: AIST Palm Sized Superfine Inkjet Printer and Original Superfine Inkjet Printer

  

Credit AIST  

Superfine inkjet technology developed at AIST’s Nanotechnology Research Institute is being commercialized by SIJ Technology, Inc, an AIST  spin-off company. The technology allows the ejection of super-fine liquid droplets smaller than the conventional droplets ejected by a home-use conventional inkjet printer. The revolutionary autonomous ink-jet method developed by Dr. K.Murata, NRI, AIST allows production and arrangements of dots with a minimum size of less than one micron, which corresponds to sub-femtoliter units in volume. This volume corresponds to a 1/1000 of the volume of the dots dispensed using the ink-jet devices currently on the market, which places this technology at the top of circuit printing technologies in the world

The super-fine inkjet technology developed by the Nanotechnology Research Institute of AIST allows the ejection of super-fine droplets much smaller than the conventional droplets ejected by a conventional inkjet printer-at least 1/10 smaller in size and 1/1000 smaller in volume.

 Figure Comparison of Discharged Ink Drop Size

Credit: SIJ Technology Inc.

SIJ Technology, Inc.  is engaged in the research and development with AIST and Harima Chemical to commericialize super-fine inkjet technology.   Using this newly developed technology, the team has confirmed that diverse materials such as nanotubes, electroconductive polymers and ceramics can be used as solutes for the ink. At the same time, tests using NanoPaste®, stable dispersion of metal particles developed by Harima Chemicals, have been carried out, resulting in successful circuit printing on diverse substrates such as glass or polyimide. This result shows that it is possible to directly print ultrafine metallic wire of only a few microns in width.

Figure: Using NanoPaste® to Draw a Super-Fine Wiring Pattern

Credit:  SIJ Technology Inc.

This technology can be applied not only to surface mounting related technologies but also to innovative applications in other nanotechnology fields such as biotechnology, optical and ultrafine processing technologies. Harima and AIST have filed U.S. Patent Application 20060286301 to protect NanoPaste® compositions and superfine inkjet technology.  

To deepen the scope of the research, and to expand the range of applications in this field, AIST, SIJTechnology, Inc.  and Harima are engaged in an ambitious joint research program that includes development of a range of metal nanoparticles for circuit printing.

An interesting aspect to metals is that for particles smaller than 20 nm in diameter, the effective melting point decreases dramatically. For example, the melting point of a super-fine silver particle may be as low as room temperature, whereas a micron sized particle of silver melts at 961ºC.  

Using a solution with these nano-size particles as ink, with out novel printer, enables maskless patterning with a line width of several microns, which is comparable to the photolithographic methods, but at room temperature and normal atmospheric pressure.

Because super-fine liquid droplets dry very quickly, the droplets can be accumulated to form a three-dimensional structure by shooting them at a fixed target.

Figure:  Forming a three-dimensional structure.

Credit SIJ Technology Inc.

Photo: Circuit boards and structures fabricated by super-fine inkjet

 Credit: AIST