Mitochondria act as the power plants for our cells. Biologists think that dysfunctional mitochondria could be linked to conditions such as diabetes, cancer, and aging. To study the differences between healthy and unhealthy mitochondria and better understand the structures’ role in disease, researchers developed a new nanofluidic device that can trap individual mitochondria for spectroscopic analysis (Anal. Chem. 2013, DOI:10.1021/ac4010088).

Mitochondria synthesize the molecule ATP, which fuels many of the cell’s biochemical processes. To drive ATP synthesis, mitochondria pump protons across a pleated inner membrane, building up an energy potential. Peter J. Burke at the University of California, Irvine, and his colleagues wanted to study single mitochondria to get better insight into the conditions that disrupt this membrane potential. For example, if the potential drops significantly, it triggers cell death, or apoptosis. Cells that resist apoptosis can lead to tumors.

Burke’s team used soft lithography to etch a silicon chip that served as a mold to make a nanofluidics device out of the polymer polydimethylsiloxane. “The hardest part was to design a chip with a channel that was small enough to trap one—and only one—mitochondrion,” Burke says. The device had channels 500 nm high and 2 μm wide.

To monitor the membrane potential of mitochondria trapped in the channels, the researchers first stained the organelles with fluorescent dye molecules. The charged dyes make the organelles glow different colors depending on the membrane potential: High potentials lead to a reddish glow, and low potentials create a green color.

The team pumped a solution of the dyed mitochondria into their device and measured each organelle’s fluorescence. The organelles’ potentials responded as predicted when the researchers added chemicals known to affect mitochondria function. For example, spiking the solution with pyruvate and malate, both involved in the metabolic pathway mitochondria use to make ATP, caused the membrane potential to increase.

Burke thinks the technique could help scientists screen the effect of drugs for cancer and other conditions on mitochondria.

Chemical & Engineering News
ISSN 0009-2347
Copyright © 2013 American Chemical Society

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• Resume
• Transcripts (college and grad), unofficial OK
• Statement of purpose (if you have one)
• GRE scores (if you have them), unofficial OK

I prefer these all at once, if possible by email, but paper copies in my mailbox are ok. I will treat them as 100% confidential.

The more information I know about you, the better the LOR will be.

If letter is to be sent by mail, provide me with pre-addressed, pre-stamped envelopes, including my name and my return address.

If you would like to do individual research with me, provide the same information to me please, again preferably by email.

Again, I will treat them as 100% confidential.

Transistor in study by University of California students
The transistor basically employs a tangle nature of carbon nano-tubes. Specifically this structure is very good in case of transportation of electrons as compared to our normal transistor. Caltech research students have been focusing on the difference the structure makes depending on the concentration of these carbon nano-tubes. So in a simple demonstration, by drying a sample of ink, the team discovered that the density of carbon nano-tubes does have an effect on working of the printing devices.

One of the key researchers in the team Nima Rouhi observed a wafer sample under an electron microscope only to find out the precise density which can be used to optimize the printing capability of the gadget. When the concentration of carbon nanotubes is around 100 per square micron, the difference in magnitude of current in transistor’s ON and OFF state was observed to be least. This was under the laboratory conditions. The team also found out some probable reasons of this phenomenon. Rouhi believes that perhaps it was because of presence of some stray metallic nanotubes in the semiconducting inks. The work of these metallic nanotubes is to serve as a connection between the source and the drain. So, more the number of these nanotubes, the efficient will be the performance of transistors.

A similar type of experiment was earlier conducted by Sunchon National University, South Korea; however they did not taken into account the concentration of nanotubes in improving the efficiency of these transistors. The South Korean university had reportedly made one bit flexible RFID tags with Carbon nanotubes.

The team has found out the electron mobility of its fastest device to be about 90cm2/Vs. The research study of the students has been published in Advanced Materials.

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The awards are the result of the fiscal 2010 competition that ARO, ONR, and AFOSR conducted under the DoD Multidisciplinary University Research Initiative (MURI) program.  The MURI program supports research by teams of investigators that intersect more than one traditional science and engineering discipline in order to accelerate both research progress and transition of research results to application.  Most MURI efforts involve researchers from multiple academic institutions and academic departments.  Based on the proposals selected in the fiscal 2010 competition, a total of 67 academic institutions are expected to participate in the 32 research efforts.

The MURI program complements other DoD basic research programs that support traditional, single-investigator university research by supporting multidisciplinary teams with larger and longer awards.  The awards announced today are for a five year period subject to availability of appropriations and satisfactory research progress.  Consequently, MURI awards can provide greater sustained support than single-investigator awards for the education and training of students pursuing advanced degrees in science and engineering fields critical to DoD, as well as for associated infrastructure such as research instrumentation.

The MURI program is highly competitive.  ARO, ONR, and AFOSR solicited proposals in 30 topics important to DoD and received a total of 411 white papers, which were followed by 152 proposals.  The awards announced today were selected based on merit review by panels of experts.

The list of projects selected for fiscal 2010 funding may be found on the Web at: http://www.defense.gov/news/d20100716MURI.pdf .

CORRECTION:  July 19, 2010 – Under MURI Topic 15, Michigan State University is corrected from University of Michigan.

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With major university programs announcing breakthroughs in nano-scale radio devices, something is afoot. But why are researchers focusing so much attention on radio? Because when it comes to marketable products, nano has been big on promises, but small on delivering, according to Dr. Peter Burke, Ph.D., associate professor of electrical engineering and computer science at the University of California, Irvine.

“In electronics there has been a shortage of demonstrations,” says Burke. “We have had many ‘proposed’ real-world applications, but not enough demonstrations.”

Burke notes that announcements touting denser memory or faster CPUs require low-cost manufacturing which hasn’t arrived yet for nanotechnology, whereas his goal was to show a real-world application.

In October 2007, Burke and his team announced the world’s first working radio system that could receive radio waves wirelessly and convert them to sound signals through a nano-sized detector. In this age of micro computer chips, the announcement was still a newsworthy event.

The “carbon nanotube radio” device is thousands of times smaller than the diameter of a human hair. Burke’s demonstration had the detector integrated into a complete radio system and used it to transmit classical music wirelessly from an iPod to a speaker several feet away from the music player.

While carbon nanotubes are still a very young technology, they detect radio waves by using the same principle as an old standby of AM, the crystal diode radio.

“The only difference is that instead of the crystal we’re using nanotubes,” said Burke. “There’s no limit to the frequency it would work at, and we actually used a one gigahertz carrier wave that we generated in the lab because we wanted our own little radio station.”

Burke is the first to admit that his wasn’t the first nano-sized radio wave detector demonstration, but he says the project broke new ground by creating a complete, nano-sized radio system.

Moreover, the study shattered doubts about the feasibility of manufacturing nano-scale radio component, ones that could lead to a “truly integrated nano-scale wireless communications system.”

In fact, just such a system was recently announced by John Rogers, a professor of Materials Science and Engineering at the University of Illinois.

Rogers developed a nanotube-transistor radio system based on a heterodyne receiver design consisting of four capacitively coupled stages: an active resonant antenna, two radio-frequency amplifiers and an audio amplifier. Headphones were plugged directly into the output of a nanotube transistor. The design incorporated seven nanotube transistors into each radio. During the demonstration, researchers tuned to WBAL(AM) at 1090 kHz in Baltimore and heard a traffic report.

Making the tiniest radio isn’t the ultimate goal for Rogers. Instead, the nanotube radio represents a milestone for proving that the technology is commercially competitive.

In benchmarking studies against silicon, measurements indicated significant advantages in comparably scaled devices. The ongoing research in nanotechnology has produced evidence that carbon nanotube transistors can be used for manufacturing low-power, high-speed transistors.

Not surprisingly, such potential is receiving support from industrial sectors and the U.S. government. Roger’s project was done in collaboration with radio frequency electronics engineers at Northrop Grumman Electronics Systems in Linthicum, Md. The National Science Foundation and U.S. Department of Energy provided funding.

The interest is justified, says Burke.

“The noise, linearity, and fidelity that are important for radio communications can actually be improved with this technology,” he said.

“It’s still speculative but there are good physics reasons. The current flows in only one direction because the wire is so tiny. It can only go forward or back, but not left, right, up or down. In the Illinois work there are a lot of wires in parallel to get enough signal, but each electron flows through one tube at a time. Of course, no two electrons can be in the same place at the same time so the noise and current that flows is actually correlated and the randomness is somehow reduced because of this principle.”

With such advantages, the next question would be how long until we see products.

Burke notes that major corporations and research institutions are engaged in a race to bring such products to market, and he too, is on a fast track to commercialization.

In 2006, he launched RF Nano, with $1.5 million in venture capital, plus funding from the U.S. Army and the National Science Foundation, for carbon nanotube antennas, FETs, and integrated nanotube systems. Burke says he has received interest from radio industry manufacturers and others in related fields, but there are still some manufacturing issues to address.

Rogers is a little more optimistic. He announced that nanotube devices and circuits are now possible, thanks to a novel growth technique developed with colleagues at the University of Illinois, Lehigh and Purdue universities.

The breakthrough produces linear, horizontally aligned arrays of hundreds of thousands of carbon nanotubes, and they function collectively. Moreover, the process produces a thin-film semiconductor material so the arrays can be integrated into electronic devices and circuits using conventional chip-processing techniques.

The analog radio frequency market offers great potential for Rogers, and a scenario where products filter down from the military is likely, according to predictions from Dr. John Przybysz, Ph.D., a University of Illinois alumnus and a senior consulting engineer at Northrop Grumman.

Przybysz says nanotube technology is a breakthrough in power requirements for military sensor systems because they perform equally with other microwave transistors but use much less power than today’s semiconductor devices. For example, batteries that expired after two days usage could now last up to two weeks due to the lower power consumption of nanotube transistors.

Ultimately, whether it’s a military application, or commercial, nanotechnology is viewing radio as an industry with high potential for short-term applications.

Looking a little farther out, Burke believes that the potential isn’t limited to traditional radio communications.

“Our radio receiver is atomic scale but the battery and antenna are large,” says Burke. “If we eliminated the battery and reduced the antenna we could insert it into an individual cell so we communicate information back and forth between the cell and the outside world. It’s more futuristic, but it’s also more exciting.”

Comment on this or any article to radioworld@nbmedia.com. Contact the author at eritchie@pacbell.net.

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US scientists have unveiled a detector thousands of times smaller than the diameter of a human hair that can translate radio waves into sound.

According to a University of California team, the study marks the first time that a nano-sized detector has been demonstrated in a working radio system.

Made of carbon nanotubes a few atoms across, it is almost 1,000 times smaller than current radio technology.

Peter Burke and Chris Rutherglen incorporated the microscopic detector into a complete radio system.

They used it to transmit classical music wirelessly from an iPod to a speaker several metres away from the music player.

Full details of their findings will be published next month in the American Chemical Society’s Nano Letters.

“Though we have only demonstrated the critical component of the entire radio system out of a nanotube (the demodulator), it is conceivable in the future that all components could be nanoscale, thus allowing a truly nanoscale wireless communications system,” they write.

Smart dust

Many companies are interested in the long-term potential of carbon nanotubes – tiny cylinders of carbon that measure just a few billionths of a metre across.

Kris Sangani, Consumer Electronics Editor at the Institution of Engineering and Technology, UK, one of the world’s leading professional societies, said there were many possible real world applications of “microscopic radio technology”- in medicine, commerce and on the battlefield.

He said the real challenge for industry was to miniaturise not just radio technology but other components such as sensors, the power supply and processors.

“Scientists are looking at carbon nanotubes to miniaturise all other technologies as well,” he told BBC News. “If you can combine miniaturisation with cost control; that type of technology would be ubiquitous.”

Such a development would bring the concept of smart dust – a cluster of devices, smaller than a grain of sand, equipped with wireless communications that can detect the likes of light, temperature, or vibration – into the realms of reality rather than science fiction.

Future uses might include meteorological, geophysical and biological research sensors. They could also be used for discreet military surveillance, or to create a distributed internet that would be accessible anywhere.

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“It’s not clear whether there would be any advantage to the average consumer,” conceded Peter J. Burke, the associate professor in U.C. Irvine’s electrical engineering department who oversaw the research and co-authored the Nano Letters paper. “We don’t know what you’d do with a radio so small you couldn’t see it.”

So far, the entire radio isn’t that small. Chris Rutherglen, the grad student at the University of California at Irvine who built the device, has constructed a key part–a demodulator for all you radio buffs–out of a carbon nanotube 50 microns long and about 1.5 nanometers wide. This is the component that processes the incoming radio signal and then passes it on to the amplifier.

A true nano radio would include a host of other similarly tiny components, including an antenna, filters and amplifiers and other signal and power processors. Designs for some of these have been created while others remain on the research world’s “to do” list, but, according to Nano Letters, this is the first time that anyone has taken any of these nano-components, plugged into the other elements of a radio and actually received and emitted clear sounds

In this video, Mr. Rutherglen shows the device receiving a signal, broadcast from accross his workbench of a lilting melody by O’Carolan, the 17th Irish harpist.

The radio featured in the paper reminded me of the scene in the time travel movie “Peggy Sue Got Married” where Peggy is briefing a nerdy high school classmate about how entertainment products get miniaturized in the future. “Everything else gets small, but for some reason, portable radios get enormous,” she says.

So what is the goal? This appears for now to be one of those “do it first and then we’ll think of something” research efforts. But here is one hint. The project is funded by the Defense Department.

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The nanotech device is a demodulator, a simple circuit that decodes radio waves and turns them into audio signals. By hooking the decoder up to two metal wires, University of California at Irvine professor Peter Burke transmitted music via AM radio waves from an iPod to speakers across the room.

“People have been working on nanoelectronics for many years, and there have been advances at the device level on switches and wires,” said Burke, who reported his findings in the November 14 issue of the American Chemical Society’s Nano Letters. “This work takes a step towards showing nanoelectronics in systems.”

The process centers on working with tiny tubes of carbon only discovered in the 1980s. They are sometimes called buckytubes, after the noted inventor Buckminster Fuller.

Nanoelectronic systems are considered crucial to the continued miniaturization of electronic devices. Many companies are interested in the long-term potential of the technology. Nanomix has received over $15 million in venture capital to commercialize various nanoelectronic devices from Okapi Venture Capital. The company intends to commercialize carbon nanotubes that will work with standard semiconductor technologies.

Burke’s system is not wholly constructed of nanomaterials. Aside from the demodulator, the rest of the radio setup was off-the-shelf. But the nanocomponent is a crucial step in developing a fully nano-sized radio.

“Though we have only demonstrated the critical component of the entire radio system out of a nanotube (the demodulator), it is conceivable in the future that all components could be nanoscale, thus allowing a truly nanoscale wireless communications system,” Burke wrote in the paper.

François Baneyx, director of the Center for Nanotechnology at the University of Washington, said nanotubes have attracted a lot of attention because of unique electrical properties that arise at the atomic scale.

“They can behave as a semiconductor or metallic system and they have a very high physical strength,” he said. “Researchers are actively working on a large number of nanotechnology applications. In nanoelectronics the focus is on the unique properties that arise at the nanoscale. They are looking to take advantage of the electronic properties of the nanotubes.”

While the potential for nanoelectronics is big, major manufacturing problems remain. When scientists are working at the atomic scale, imperfections of a couple of atoms have drastic repercussions.

“If one atom is out of place in a regular transistor, it’s not a big deal,” Burke said. “If one atom is out of place in the nanotube, it has a big impact on the electronic properties.”

That impact means that it is nearly impossible to make identical components time and again, an obvious necessity for commercial production.

“The cost and manufacturability are the big unsolved issues in nanotechnology,” Burke said.

Burke’s team is also looking at the interfaces between biological systems and nanotechnologies. He sees opportunities in manipulating human proteins, since they are about the same size as the nanoelectronics.

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