OT-Luna Innovations announces continuous production of carbon nanomaterials

http://lunainc.com/advances-nanomanufacturing-scale-up-cost-control/

Nanomanufacturing is the production of nanoscaled materials such as carbon nanotubes, nanosheets like graphene, and carbon cage materials like fullerenes and Luna’s proprietary Trimetaspheres®.  As these become more prevalent in everyday applications the biggest challenges will be how to produce them on large scales at low costs.

Traditional production involves a batch process arc reactor where a carbon rod is fed into the plasma reactor and burned to soot.  When the rod is expended the reactor is shut down, the soot is collected and the species of interest (single walled or multi walled nanotubes, buckyballs, etc.) are recovered.  For more complex nanomaterials like Trimetaspheres®, carbon rods are drilled out and packed with other elements of interest, but the rest of the process is the same.  This batch process is slow, labor intensive, and uses expensive raw materials like helium gas.

At our nanomanufacturing facility in Danville VA, we have successfully designed, fabricated, and automated reactors for more continuous production of carbon nanomaterials.  Through a series of iterative prototyping we have moved from a small reactor that only produced grams of material to one that now produces kilograms.  Instead of manufacturing with a single 16 inch rod that must be used and then exchanged, the new reactor design can accommodate three 32 inch rods.  In addition, supplemental elements can be added separately.  Rods do not need to be drilled out which keeps the material costs down.  Finally, the system needs only nitrogen to run – helium is not required.  This further suppressed raw material costs.

A prototype version of the vertical three-phase AC arc discharge reactor was recently published in the journal – Fullerenes, Nanotubes and Carbon Nanostructures, 23:7, 612-617, DOI: 10.1080/1536383X.2014.941104, http://dx.doi.org/10.1080/1536383X.2014.941104, and a patent application was filed, Publication Number: WO2014152062. It was experimentally proven that the new three-phase AC arc discharge process is truly scalable for the production of our Trimetasphere® fullerenes for commercial applications including MRI contrast agents. The internal high velocity plasma jet is preferable for Trimetasphere® fullerene formation but not for other fullerene nanomaterials of low commercial values. The most interesting finding is a 5 fold increase in yield due to usage of the three-phase setup.

Figure: Pareto of cost drivers for the state of art two electrodes DC and our new three-phase process showing a cost reduction of 70–80%.

Using our cost model (labor, overhead, materials, energy, equipment utilization), the cost reduction is estimated at 70–80% compared to the current state of the art.  Additional cost savings would be realized from the purification step where the suppressed yields of non-desired fullerenes simplifies the process and saves expensive chemicals.  In summary, Luna has created a new nanomaterial production reactor that improves yield, volume, and cost effectiveness over existing processes. As nanomaterials play bigger roles, Luna is ready to assist in development, applications, and production.

Carbon and terahertz nanotechnology: a promising alliance

Anna Demming

anna.demming@iop.org

Publishing Editor, IOP Publishing, Bristol, UK 

Anna Demming 2014 Nanotechnology 25 320201doi:10.1088/0957-4484/25/32/320201

© 2014 IOP Publishing Ltd
Published 22 July 2014

http://iopscience.iop.org/0957-4484/25/32/320201/article

The equations that first linked electric and magnetic interactions to explain light celebrate their 150th anniversary this year. Now known as the Maxwell equations, their contribution to the theory of relativity led Albert Einstein to remark, 'One scientific epoch ended and another began with James Clerk Maxwell'. They have since laid the bedrock for modern day electronics, photonics and magnetism and have been integral to a number of studies of nanoscale systems over the years. Today many key areas of development in current nanotechnology research derive from electromagnetic effects as highlighted by Satoshi Kawata, Adarsh Sandhu and Jennifer Dionne in a recent Nanotechnology Discussion podcast on Maxwell's equations at the nanoscale [1]. One region of the electromagnetic spectrum where a comparatively new alliance has been forged with nanoscale research is the terahertz regime.

Although terahertz wavelengths—measuring 0.1–100 mm—exceed the dimensions of nanostructures, terahertz radiation can be useful for probing these systems because many of their dynamical processes operate around terahertz timescales. Examples can be found in the recent Nanotechnology special section dedicated to terahertz nanotechnology [2]. Here Hannah Joyce, Michael Johnston and colleagues at the University of Oxford in the UK and the Australian National University report studies using an optical pump-terahertz probe approach to probe carrier dynamics in semiconductor nanowires made from Group III and V compounds [3]. The technique has the advantages of being non-contact and operating at room temperature, and provided information on the carrier lifetime that may prove valuable for matching different nanowires to different applications.

The same issue includes a number of approaches for harnessing nanosystems for terahertz detection, such as nanowire-based field effect transistors [4]. Meanwhile Joo-Hiuk Son provides a review of the principle, characteristics and applications of molecular imaging with terahertz electromagnetic waves [5]. The review describes how terahertz radiation is a relatively safe imaging tool (compared with, for example, x-rays) as well as how the sensitivity to vibrational modes of water molecules can be enhanced using nanoparticles for more effective medical imaging and diagnosis.

The emergence of carbon-based nanoelectronics has already greatly modified the outlook for next-generation devices [6]. In this issue, Richard Hartmann from De La Salle University in the Philippines, Junichiro Kono from Rice University in the US and Mikhail Portnoi from Universidade Federal do Rio Grande do Norte in Brazil present an overview of what carbon nanomaterials offer for the future of terahertz science and technology [7].

As explained in the review, 'In this frequency range, electronic transport and optical phenomena merge with one another, and classical waves (in the microwave region) make the transition to quantum mechanical photons (in the optical regime)'. It is easy to imagine that the extraordinary optoelectronic properties of carbon nanotubes and graphene might make them ideally suited to applications exploiting these frequencies.

In the review the researchers point out that both carbon nanotubes and graphene are expected to show exotic THz dynamics and that these 'can lead to innovative optoelectronic applications'. They attribute these characteristics to the unique low-dimensional band structure of carbon nanomaterials and the nature of the quantum-confined interactions between charge carriers. Electric and magnetic fields and gating can also trigger activity in the terahertz regime.

The review highlights the progress made in understanding and optimising carbon nanotube transistors, antennae and polarizers, as well as nonlinear processes, plasmonics and detectors based on graphene at terahertz frequencies. These potential avenues for applications join a long list as research activity into carbon nanomaterials attracts ever increasing interest, yet the unique characteristics of both terahertz radiation and carbon nanostructures suggests a disarmingly promising alliance.

While Hartmann, Kono and Portnoi point out that many challenges lie ahead in the field they conclude that nanocarbon THz technology has great potential for development in the coming years. Progress in the field to date certainly makes a convincing case for the future of nanocarbon THz technology, but in the words of James Clerk Maxwell himself as he contemplated his theory of the colour of light, 'time will show' [8].

References

[1]

Nanotechnology Discussions podcasts http://iopscience.iop.org/0957-4484/page/Nanotechnology%20Discussions%20podcasts

[2]

Special section on terahertz nanotechnology 2013 Nanotechnology 24 http://iopscience.iop.org/0957-4484/24/21

[3]

Joyce H J, Docherty C J, Gao Q, Tan H H, Jagadish C, Lloyd-Hughes J, Herz L M and Johnston M B 2013Nanotechnology 24 214006IOPscience

[4]

Romeo L, Coquillat D, Pea M, Ercolani D, Beltram F, Sorba L, Knap W, Tredicucci A and Vitiello M S 2013Nanotechnology 24 214005IOPscience

[5]

Son J-H 2013 Nanotechnology 24 214001 Principle and applications of terahertz molecular imagingIOPscience

[6]

Avouris P, Chen Z and Perebeinos V 2007 Nat. Nanotechnology 2 605–15CrossRef

[7]

Hartmann R R, Kono J and Portnoi M E Nanotechnology 25 322001IOPscience

[8]

Maxwell, in a letter to William Thomson 1990 The Scientific Letters and Papers of James Clerk Maxwell: 1846-1862 245

Improvements in MRIs, other image-detection applications on the horizon

http://www.sciencecodex.com/improvements_in_mris_other_imagedetection_applications_on_the_horizon-135395

LIVERMORE, Calif. — Researchers at Sandia National Laboratories, along with collaborators from Rice University and the Tokyo Institute of Technology, are developing new terahertz detectors based on carbon nanotubes that could lead to significant improvements in medical imaging, airport passenger screening, food inspection and other applications.

A paper in Nano Letters journal, "Carbon Nanotube Terahertz Detector," debuted in the May 29 edition of the publication's "Just Accepted Manuscripts" section. The paper describes a technique that uses carbon nanotubes to detect light in the terahertz frequency range without cooling.

Historically, the terahertz frequency range — which falls between the more conventional ranges used for electronics on one end and optics on another — has presented great promise along with vexing challenges for researchers, said Sandia's François Léonard, one of the authors.

"The photonic energy in the terahertz range is much smaller than for visible light, and we simply don't have a lot of materials to absorb that light efficiently and convert it into an electronic signal," said Léonard. "So we need to look for other approaches."

Terahertz technology offers hope in medicine and other applications

Researchers need to solve this technical problem to take advantage of the many beneficial applications for terahertz radiation, said co-author Junichiro Kono of Rice University. Terahertz waves, for example, can easily penetrate fabric and other materials and could provide less intrusive ways for security screenings of people and cargo. Terahertz imaging could also be used in food inspection without adversely impacting food quality.

Perhaps the most exciting application offered by terahertz technology, said Kono, is as a potential replacement for magnetic resonance imaging (MRI) technology in screening for cancer and other diseases.

"The potential improvements in size, ease, cost and mobility of a terahertz-based detector are phenomenal," he said. "With this technology, you could conceivably design a hand-held terahertz detection camera that images tumors in real-time, with pinpoint accuracy. And it could be done without the intimidating nature of MRI technology."

Researchers at Sandia National Laboratories, Rice University and the Tokyo Institute of Technology developed a terahertz detector using several nanoscopic-sized tubes, creating a macroscopic thin film that contains a mix of metallic and semiconducting carbon nanotubes.

(Photo Credit: Dino Vournas, Sandia National Laboratories)

Carbon nanotubes may help bridge the technical gap

Sandia, its collaborators and Léonard, in particular, have been studying carbon nanotubes and related nanomaterials for years. In 2008, Léonard authored The Physics of Carbon Nanotube Devices, which looks at the experimental and theoretical aspects of carbon nanotube devices.

Carbon nanotubes are long, thin cylinders composed entirely of carbon atoms. While their diameters are in the 1- to 10-nanometer range, they can be up to several centimeters long. The carbon-carbon bond is very strong, so it resists any kind of deformation.

The scientific community has long been interested in the terahertz properties of carbon nanotubes, said Léonard, but virtually all of the research to date has been theoretical or computer-model based. A handful of papers have investigated terahertz sensing using carbon nanotubes, but those have focused mainly on the use of a single or single bundle of nanotubes.

The problem, Léonard said, is that terahertz radiation typically requires an antenna to achieve coupling into a single nanotube due to the relatively large size of terahertz waves. The Sandia, Rice University and Tokyo Institute of Technology research team, however, found a way to create a small but visible-to-the-naked eye detector, developed by Rice researcher Robert Hauge and graduate student Xiaowei He, that uses carbon nanotube thin films without requiring an antenna. The technique is thus amenable to simple fabrication and represents one of the team's most important achievements, Léonard said.

"Carbon nanotube thin films are extremely good absorbers of electromagnetic light," he explained. In the terahertz range, it turns out that thin films of these nanotubes will soak up all of the incoming terahertz radiation. Nanotube films have even been called "the blackest material" for their ability to absorb light effectively.

The researchers were able to wrap together several nanoscopic-sized tubes to create a macroscopic thin film that contains a mix of metallic and semiconducting carbon nanotubes.

"Trying to do that with a different kind of material would be nearly impossible, since a semiconductor and a metal couldn't coexist at the nanoscale at high density," explained Kono. "But that's what we've achieved with the carbon nanotubes."

The technique is key, he said, because it combines the superb terahertz absorption properties of the metallic nanotubes and the unique electronic properties of the semiconducting carbon nanotubes. This allows researchers to achieve a photodetector that does not require power to operate, with performance comparable to existing technology.

A clear path to performance improvement

The next step for researchers, Léonard said, is to improve the design, engineering and performance of the terahertz detector.

For instance, they need to integrate an independent terahertz radiation source with the detector for applications that require a source, Léonard said. The team also needs to incorporate electronics into the system and to further improve properties of the carbon nanotube material.

"We have some very clear ideas about how we can achieve these technical goals," said Léonard, adding that new collaborations with industry or government agencies are welcome.

"Our technical accomplishments open up a new path for terahertz technology, and I am particularly proud of the multidisciplinary and collaborative nature of this work across three institutions," he said.

In addition to Sandia, Rice and Tokyo Tech, the project received contributions from researchers taking part in NanoJapan, a 12-week summer program that enables freshman and sophomore physics and engineering students from U.S. universities to complete nanoscience research internships in Japan focused on terahertz nanoscience.

This photograph depicts the terahertz detector developed by researchers at Sandia National Laboratories, Rice University and the Tokyo Institute of Technology. The terahertz radiation is captured by a carbon nanotube thin film contacted by two gold electrodes.

(Photo Credit: Rice University)

Abstract-Microwave to Terahertz: Characterization of Carbon-Based Nanomaterials

2

Author(s)

Liang, M. ; Electrical/Computer Engineering Department, The University of Arizona, Tucson, AZ 85750 USA ; Xin, H.

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6717099

Microwave engineering has been an exciting forefront of modern technology and one of the major enablers of the fast-expanding information era. Since its formal establishment in the 19th century, this classic field has experienced many revolutions powered by discoveries of new materials and inventions of related devices. Rapid developments in nanotechnology in recent years have offered exciting possibilities for revolutionary discoveries in many branches of human endeavor. Nanomaterials and associated devices are being widely studied and developed for applications in electronics, optics, biology, energy, etc. Although it has been suggested that nanomaterials such as carbon nanotubes (CNTs) and graphene-based devices may work well in the microwave or even terahertz (THz) range [1], [2], most of the previous measurements were done at dc or lower frequency ( f < 300 MHz) [3]-[5]. The characterization techniques of nanomaterials at microwave and THz frequency are important for both fundamental research and practical applications before proposed components such as antennas, interconnections, and circuit building blocks [6]-[8] can be realized. In this article, a review of characterization methods and associated challenges for various CNT and graphene samples from microwave to THz frequencies is presented, and pros and cons of the approaches are highlighted.