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Graphene's Use in RF transistors Gets a Boost from Faster and Easier Manufacturing Technique

IBM, and in particular Phaedon Avouris and his colleagues at IBM’s T.J. Watson Research Center, has been focused on developing graphene for use in electronics applications.

Last year we reported on their work in creating a band gap for graphene and now Avouris and his team are reporting on a new route to fabricating graphene-based transistors that is compatible with current manufacturing techniques.

The research was initially published in the journal Nature and focused its efforts with graphene in one of its favored potential electronic applications: radio frequency (RF) transistors.

Where previous attempts to create RF transistors out of graphene suffered from a fabrication process that was a manual and time consuming process, the IBM researchers employed a clever vapor deposition method that avoided both the adverse effects other vapor deposition techniques had on the electronic properties of graphene and kept away from the labor intensive techniques.

The researchers grew the graphen on copper film and then deposited it on a diamond-like carbon with a resulting transistor that has “…cut-off frequencies as high as 155GHz…for 40-nm transistors.”

In the Chemical & Engineering News article cited above Frank Schwierz, a device physicist at the Technical University of Ilmenau, in Germany, offered some context for the work.

“The approach of the IBM team is very interesting because it is compatible with common semiconductor processing,” Schwierz is quoted as saying in the C&E News article. “At this early stage, before the fabrication method has been optimized, Schwierz is cautious about calling the technique a breakthrough. “But it may turn out to be very useful in the future.”

Terabyte USBs Possibly Available Soon Are Fruit of EU-funded Nanotech Project

I came across an interesting interview with Dr. Simon Elliott from the Tyndall National Institute in Ireland, who was part of an EU-funded project called REALISE  (Rare Earth Oxide Atomic Layer Deposition for Innovation in Electronics), which ended in 2009. (Why the EU is so enthralled with the use of acronyms for its research projects continues to bewilder me.)

What Elliot describes is the application of rare earth oxides used in combination with ALD to boost memory chip capabilities. With at least one near-commercial application of the research expected to be “a one terabyte USB stick in the near future.”

The EU project started out humbly enough with the aim of seeing what was possible if they started using rare earth oxides in combination with an ALD. Elliot and his team at Tyndall were given the charge of determining the properties of these rare earth oxides and discovered, for instance, that one of the materials they tested possesses insulating properties three times better than alumina, the previous best material for this purpose.  What this translates into is that if the insulating properties are three times better, you can make the devices three times smaller.

It seems a good portion of the research was devoted to seeing how the new materials worked when being applied on 3D structures for capacitors with ALD. The aim, of course, is that if use structures in 3D then you use up less surface area of the wafer.

What I found intriguing about Elliot’s interview was his mention of the “project partners” belief that any extra associated costs with this method of using the materials on 3D structures for capacitors would be more than outweighed by the benefits derived.

So just out of curiosity I took a look at who the commercial partners on the project were. Among the larger companies were STMicroelectronics, Infineon Technologies and Philips Electronics. Could we see one or all of these offering a commercial product based on this research soon?

Doping of Quantum Dots Promises Both Improved Efficiency and Lower Costs of Solar Cells

While carbon nanotubes have been the darling of the nanoparticle universe, quantum dots have been that mysterious and alluring nanoparticle that seems to keep researchers coming back for more.

We’ve seen them being proposed as the backbone for quantum computers and we have observed them being used to improve LED lighting.

One application area that always gets some attention when the topic of quantum dots is discussed is solar power. They get presented as a possible silver bullet for spiking the efficiency of solar cells with the proposed abilities either to enable electron multiplication or to create so-called “hot-carrier” cells. These proposals are not without skeptics.

But if the higher efficiency promised by quantum dots should fall short, then we still have the potential for them making solar power cheaper.

It is in this latter application niche that research covered here on the pages of Spectrum in which quantum dots have been doped that quantum dots look more attractive for solar cells.

In the Spectrum article, Eran Rabini, of Tel Aviv University and one of the lead researchers on the project, when commenting on the research’s potential for producing junctions consisting of films made of n-type and p-type nanocrystals suggests, "We might be able to make them cheaper (solar cells, ed.), and maybe at the end of the road they would also be more efficient."

I like when the terms “more efficient” and “cheaper” are brought together when discussing solar cells. 

Material-by-Design Paradigm Suggested with New Bacteria Killing Nanoparticle

The Twitter world, along with much of technology press, is aflutter with news that researchers at IBM’s Almaden Research Center in San Jose, CA, along with testing assistance from the Institute of Bioengineering and Nanotechnology in Singapore,  have developed a nanoparticle that could combat bacteria that have developed resistance to antibiotics

The research, which was initially published in the journal Nature Chemistry, claims to report “the first biodegradable and in vivo applicable antimicrobial polymer nanoparticles synthesized by metal-free organocatalytic ring-opening polymerization of functional cyclic carbonate.”

The nanoparticles are essentially polymers that are designed to pierce the outer membrane of certain bacteria to kill them. It is this piercing of the bacteria membrane that makes it difficult for the bacteria to develop a resistance.

While other drugs have been developed (with little success) that pierce the membrane wall of bacteria, they always suffered from their toxicity to animal cells and poor reactions to the complexity of human biology. These nanoparticles could be used in a drug, or in a topical gel, and are biocompatible.

The leader of the research James Hedrick took the body of knowledge that had been accumulated on polymer building blocks for creating nanoparticles and adapted them to this purpose. The result is a nanoparticle that has a “backbone” of a polymer that is both water soluble and attracted to the bacterial membrane. By placing hydrophobic sequences at either end of the backbone the structure begins to self-assemble into spherical nanoparticles when water is added.

The prospect of developing a drug that fights bacteria that have developed resistance to bacteria is attractive, no doubt, especially when one considers that in 2005 nearly 95,000 people in the US alone developed staph infections brought on by antibiotic resistant bacteria.

However, what I find intriguing about this story is that the IBM researchers believe they have developed a template, of sorts, for combating an assortment of bacteria.

“Through molecular tailoring," says Robert Allen, senior manager of materials chemistry at IBM Almaden, in the Tech Review article, "we can do all sorts of things." With the reporter seeming to add: “designing particles with a particular shape, charge, water solubility, or other property.”

That is perhaps the most interesting bit of this news for me because what it suggests is that the researchers have achieved a “material by design” capability that would be really remarkable.

Gelatin Nanospheres Serve as Building Blocks for Tissue Regenerative Gels

Nanowerk has a spotlight piece on a joint research project between Radboud University in the Netherlands and Sichuan University in China that has developed a method for producing oppositely charged gelatin nanospheres that enable a bottom-up approach for injectable gels that can aid in tissue repair.

The research, which was initially published in the Wiley journal Advanced Materials, improves on colloidal gels that have been developed in the past that were often cytotoxic because of their high charge density.

"We have used gelatin since both positively and negatively charged gelatin is commercially available without the need to chemically modify these biopolymers" says Huanan Wang, a PhD student in the Department of Biomaterials at Radboud University Nijmegen Medical Center, in the Nanowerk piece.

As the Nanowerk piece points out, one of the key features of this research was that they demonstrated that commercially available biopolymers, like gelatin, can be used in tissue regeneration without any additional chemical modification that could potentially negatively impact its biocompatibility.

Powering Our Electronic Devices with Nanogenerators Looks More Feasible

Professor Zhong Lin Wang, Director of the Center for Nanostructure Characterization at Georgia Tech, has managed to keep the otherwise obscure subject of the piezoelectric qualities of zinc oxide nanowires continuously in the press. I myself have alluded to his work twice on this blog (here and here).

The latest mainstream media outlet to pick up on his work is the UK-based publication the Telegraph, which gets quite excited about a presentation Dr. Wang made at the ongoing National Meeting and Exposition of the American Chemical Society.

You really have to hand it to Dr. Wang to have his presentation for an ACS meeting make it into a UK daily newspaper—chapeau. This time the trick was to bring in the prospect of an iPod that could be powered by our heartbeat. When you say “iPod” in relation to any technological development you’re sure to get mainstream media attention.

I would have happily chalked this story up to one more excellent job of getting nanomaterial research into the mainstream press, but because of recent work by Eric Pop and his colleagues at the University of Illinois’s Beckman Institute in reducing the energy consumed by electronic devices it seems a bit more intriguing now.

So low is the energy consumption of the electronics proposed by the University of Illinois research it is to the point where a mobile device may not need a battery but could possibly operate on the energy generated from piezoelectric-enabled nanogenerators contained within such devices like those proposed by Wang. (Just as a point of clarification on my previous post on the University of Illinois research, I misleadingly said that Pop’s research could mean mobile devices that run on their own thermal or mechanical energy. It would have been better to say: “mobile devices that could run on the thermal or mechanical energy they harvest.” I don’t want anyone to give up on the second law or believe that I was proposing a perpetual motion machine.) 

So,  according to Wang, five nanogenerators producing energy through the straining or flexing of nanowires brought on by the mechanical energy of your heartbeat or walking  could produce “about 1 micro ampere output current at 3 volts about the same voltage generated by two regular AA batteries.”

Research on Molecular Mechanosynthesis is Progressing Slowly

I have admired Philip Moriarty since I first saw a video of a nanotechnology debate at Nottingham University taped in 2005 in which Moriarty stood up and asked some pretty pointed questions to some of the panel members who were proposing molecular nanotechnology (MNT). (The nearly two-hour video I have included below).

The tenor of Moriarty’s questions and comments are exemplified by this comment: “To date there has not been a single mechanosynthesis experiment, in that the most basic step in terms of abstracting a hydrogen atom from a diamond surface has not been done. That has to be proved in order to demonstrate the viability of the machine approach. I’ve never been able to square that with the statement that there are no showstoppers—not one experiment has been done, correct?

I’m not sure he received an answer to that question. It’s likely he was told that Freitas and Merkle had run some computer model simulations. 

But my respect for Moriarty grew when he decided that since no one felt compelled to do these experiments, he would. And he didn’t moan about how he couldn’t get funding, he made a proposal for an experiment and got it funded. Then he set about beginning the long and arduous job of setting up experiments that weren’t done solely in the forgiving world of a computer model.

So I was intrigued to see what the update was on his research and we get it an interview with Sander Olson at the blog The Next Big Future.

The upshot is that things are not progressing well with diamonds but his work with silicon is a bit more hopeful.

So we soon get the question: Are you still a skeptic? (Just a personal note on the word skeptic, it is my sincerest hope that every scientist is an unashamed skeptic. But it seems in this context the word is presented as some kind of pejorative.) Thankfully, Moriarty without hesitations acknowledges that he indeed is a skeptic.

“I believe that the concept of molecular manufacturing - of creating macroscopic objects atom by atom for any material, is flawed,” Moriarty says in the interview. “I do not believe that this technique can be scaled-up to manufacture macrosized objects for arbitrary materials.”

Moriarty takes great pains to distinguish the recent body of thought on the subject from the original proposals of Drexler.

“In “Nanosystems” Drexler makes a careful and clever choice of the type of system required for mechanosynthesis/molecular manufacturing, taking into account the key surface science issues,” Moriatry argues. “I’ve never been able to see why it is then claimed that these schemes are extendable to all other materials (or practically all elements in the periodic table), for the reasons I discussed at considerable length in my debate with Chris Phoenix.”

Moriarty even weighs in on the Smalley/Drexler polemic that occurred on the pages of Chemical & Engineering News back in 2003.  “Richard Smalley, despite raising other important criticisms of the molecular manufacturing concept, misunderstood key aspects of mechanosynthesis and put forward flawed objections to the physical chemistry underlying Drexler’s proposals.”

A good portion of the remaining part of the interview revolves around Moriarty’s work and views on AFM and SPM research and makes the entire interview worthy for a thorough read. 

But back on the MNT front it would seem that the prospect put forward by Ray Kurzweil and others that “Around 2030, we should be able to flood our brains with nanobots…” seems more than a bit optimistic if Moriarty is hoping that by 2040 “that we are at the point where we could simply instruct a computer to build nanostructures, and let the computer handle all the details – no human operator involvement required.”

Carbon Nanotubes in Advanced Composites Enable Detection of Aircraft Defects

I have made light of some efforts to use carbon nanotubes in the filler materials for carbon fiber composites. It always struck me as more a marketing ploy than an effort to produce a carbon composite that was significantly stronger than typical varieties.

But researchers at MIT may have devised an additional way to have it make sense to include carbon nanotubes in these composites by developing a simple, hand-held device capable of detecting internal damage to composites…just as long as the composite contains carbon nanotubes.

Brian L. Wardle, associate professor of aeronautics and astronautics at MIT, along with his colleagues have developed a solution that requires only a small current be applied to the material of the aircraft that quickly heats up the carbon nanotubes and allows the use of thermographic camera for detecting flaws without the cumbersome need for heating the entire surface of the aircraft.

"It's a very clever way to utilize the properties of carbon nanotubes to deliver that thermal energy, from the inside out," says Douglas Adams, associate professor of mechanical engineering at Purdue University, in an MIT press release.

The research, which was initially published in the March 22nd online edition of the UK’s Institute of Physics journal Nanotechnology, depends on carbon nanotubes being included in the material matrix in order for it to work.

This could be a way in which carbon nanotubes will become more widely used in these advanced composites. It allows for a much cheaper inspection method than is currently available, which alone could offset the extra costs of use CNTs in the fillers for these materials.

It certainly should benefit one of the main aims of Wardle’s work, which is “to improve the performance of advanced aerospace materials/structures through strategic use of carbon nanotubes (CNTs).” 

While the US Air Force and Navy are reportedly interested in the technology, it will be interesting to see if commercial aircraft become involved. It seems now CNTs are no longer only selling their strength in composites but their ability to cheapen inspection.

3D Nanostructure for Cathodes in Batteries Could Mean Cell Phones that Charge in Seconds

No sooner do I discuss University of Illinois researchers who have created 3D antennas for mobile phones using nanotechnology than another group of researchers at the University of Illinois (this time at Urbana-Champaign) have developed 3D material for batteries that combines the qualities of supercapacitors with those of batteries and could change the entire battery paradigm. 

Professor Paul Braun and his colleagues just published in the March 20th edition of the journal Nature Nanotechnology their results that showed ultra fast charge and discharge rates by “using cathodes made from a self-assembled three-dimensional bicontinuous nanoarchitecture consisting of an electrolytically active material sandwiched between rapid ion and electron transport pathways.”

What this could mean, according to the excited science and technology press, are electric cars that could be charged in five minutes, a laptop in just a couple of minutes and a cell phone in seconds.

While thin film technology has allowed faster charging capabilities than seen in your typical li-ion batteries but it can’t store the energy well, meaning that a mobile device would run out of power in mere seconds.

What Braun and his team have done essentially is to take the thin film technology but built it up through self-assembly into a three-dimensional structure thereby increasing its surface area and its ability to store energy.

The actual structure apparently resembles a lattice of tightly packed spheres. Metal is used to fill in the spaces around the spheres and then it is all melted leaving a 3D scaffold that appears like a sponge. Then the structure is electropolished that increases the size of the pores.

The result is that lithium ions can move rapidly through the material with a high electrical conductivity.

According to Braun this could revolutionize the battery. "We like that it's very universal,” Braun is quoted as saying in a number of articles covering the report. “This is not linked to one very specific kind of battery, but rather it's a new paradigm in thinking about a battery in three dimensions for enhancing properties."

Nanoparticles Enable 3D Printing for Cell Phone Antennas

After nanotechnology manages to develop a solution for mobile devices so that they don’t need to be charged every day, I would like if nanotech could lead to a solution for the dropped call.

Mobile phones where the batteries run down in a few hours are really annoying but I think dropped calls from bad reception runs a close second in my annoyance scale.

I may not have to wait that long if research at the University of Illinois in making a 3D antenna for mobile phones can successfully make it commercially available cell phones.

The research, which was initially published in the Wiley journal Advanced Materials, employed an ink jet printing method that used silver nanoparticles and were sprayed on the inside or the ourside of a small hemispherical dome.

“To our knowledge, this is the first demonstration of 3D printed antennas on curvilinear surfaces,” Jennifer A. Lewis, the Hans Thurnauer Professor of Materials Science and Engineering and director of the Frederick Seitz Materials Research Laboratory at Illinois is quoted as saying in the University press release. “Omnidirectional printing of metallic nanoparticle inks offers an attractive alternative for meeting the demanding form factors of 3D electrically small antennas (ESAs).”

The functionality of antennas for mobile phones has not fared well in the overall miniaturization of the gadgets with characteristics such as gain, efficiency, bandwidth, and range all suffering.

According Jennifer T. Bernhard, a professor of electrical and computer engineering at Illinois, the 3D antennas that the research team has developed are an order of magnitude better in performance metrics than the typical monopole designs.

“There has been a long-standing problem of minimizing the ratio of energy stored to energy radiated—the Q—of an ESA,” Bernhard explains in the article. “By printing directly on the hemispherical substrate, we have a highly versatile single-mode antenna with a Q that very closely approaches the fundamental limit dictated by physics (known as the Chu limit).”

The researchers claim that this design can be quickly adapted to conform to different specifications, such as operating frequencies, device sizes or encapsulated designs. 

Phones that can last a month on a charge or don’t even need a battery because they can run own their own mechanical energy and no more dropped calls…mobile phones are beginning to sound a lot more attractive.



IEEE Spectrum’s nanotechnology blog, featuring news and analysis about the development, applications, and future of science and technology at the nanoscale.

Dexter Johnson
Madrid, Spain
Rachel Courtland
Associate Editor, IEEE Spectrum
New York, NY
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