Tag Archives: Northwestern University

Liquid nanolaser: the first one

According to an April 24, 2015 news item on Nanowerk, there has been a big discovery at Northwestern University (located in Chicago, Illinois, US),

Northwestern University scientists have developed the first liquid nanoscale laser. And it’s tunable in real time, meaning you can quickly and simply produce different colors, a unique and useful feature. The laser technology could lead to practical applications, such as a new form of a “lab on a chip” for medical diagnostics.

To understand the concept, imagine a laser pointer whose color can be changed simply by changing the liquid inside it, instead of needing a different laser pointer for every desired color.

In addition to changing color in real time, the liquid nanolaser has additional advantages over other nanolasers: it is simple to make, inexpensive to produce and operates at room temperature.

An April 24, 2015 Northwestern University news release by Megan Fellman (also on EurekAlert), which originated the news item, offers a little history buttressed by some technical details (Note: Links have been removed),

Nanoscopic lasers — first demonstrated in 2009 — are only found in research labs today. They are, however, of great interest for advances in technology and for military applications.

“Our study allows us to think about new laser designs and what could be possible if they could actually be made,” said Teri W. Odom, who led the research. “My lab likes to go after new materials, new structures and new ways of putting them together to achieve things not yet imagined. We believe this work represents a conceptual and practical engineering advance for on-demand, reversible control of light from nanoscopic sources.”

The liquid nanolaser in this study is not a laser pointer but a laser device on a chip, Odom explained. The laser’s color can be changed in real time when the liquid dye in the microfluidic channel above the laser’s cavity is changed.

The laser’s cavity is made up of an array of reflective gold nanoparticles, where the light is concentrated around each nanoparticle and then amplified. (In contrast to conventional laser cavities, no mirrors are required for the light to bounce back and forth.) Notably, as the laser color is tuned, the nanoparticle cavity stays fixed and does not change; only the liquid gain around the nanoparticles changes.

The main advantages of very small lasers are:

• They can be used as on-chip light sources for optoelectronic integrated circuits;

• They can be used in optical data storage and lithography;

• They can operate reliably at one wavelength; and

• They should be able to operate much faster than conventional lasers because they are made from metals.

Some technical background

Plasmon lasers are promising nanoscale coherent sources of optical fields because they support ultra-small sizes and show ultra-fast dynamics. Although plasmon lasers have been demonstrated at different spectral ranges, from the ultraviolet to near-infrared, a systematic approach to manipulate the lasing emission wavelength in real time has not been possible.

The main limitation is that only solid gain materials have been used in previous work on plasmon nanolasers; hence, fixed wavelengths were shown because solid materials cannot easily be modified. Odom’s research team has found a way to integrate liquid gain materials with gold nanoparticle arrays to achieve nanoscale plasmon lasing that can be tuned dynamical, reversibly and in real time.

The use of liquid gain materials has two significant benefits:

• The organic dye molecules can be readily dissolved in solvents with different refractive indices. Thus, the dielectric environment around the nanoparticle arrays can be tuned, which also tunes the lasing wavelength.

• The liquid form of gain materials enables the fluid to be manipulated within a microfluidic channel. Thus, dynamic tuning of the lasing emission is possible simply by flowing liquid with different refractive indices. Moreover, as an added benefit of the liquid environment, the lasing-on-chip devices can show long-term stability because the gain molecules can be constantly refreshed.

These nanoscale lasers can be mass-produced with emission wavelengths over the entire gain bandwidth of the dye. Thus, the same fixed nanocavity structure (the same gold nanoparticle array) can exhibit lasing wavelengths that can be tuned over 50 nanometers, from 860 to 910 nanometers, simply by changing the solvent the dye is dissolved in.

Here’s a link to and a citation for the paper,

Real-time tunable lasing from plasmonic nanocavity arrays by Ankun Yang, Thang B. Hoang, Montacer Dridi, Claire Deeb, Maiken H. Mikkelsen, George C. Schatz, & Teri W. Odom. Nature Communications 6, Article number: 6939 doi:10.1038/ncomms7939 Published 20 April 2015

This paper is open access.

A more complex memristor: from two terminals to three for brain-like computing

Researchers have developed a more complex memristor device than has been the case according to an April 6, 2015 Northwestern University news release (also on EurekAlert),

Researchers are always searching for improved technologies, but the most efficient computer possible already exists. It can learn and adapt without needing to be programmed or updated. It has nearly limitless memory, is difficult to crash, and works at extremely fast speeds. It’s not a Mac or a PC; it’s the human brain. And scientists around the world want to mimic its abilities.

Both academic and industrial laboratories are working to develop computers that operate more like the human brain. Instead of operating like a conventional, digital system, these new devices could potentially function more like a network of neurons.

“Computers are very impressive in many ways, but they’re not equal to the mind,” said Mark Hersam, the Bette and Neison Harris Chair in Teaching Excellence in Northwestern University’s McCormick School of Engineering. “Neurons can achieve very complicated computation with very low power consumption compared to a digital computer.”

A team of Northwestern researchers, including Hersam, has accomplished a new step forward in electronics that could bring brain-like computing closer to reality. The team’s work advances memory resistors, or “memristors,” which are resistors in a circuit that “remember” how much current has flowed through them.

“Memristors could be used as a memory element in an integrated circuit or computer,” Hersam said. “Unlike other memories that exist today in modern electronics, memristors are stable and remember their state even if you lose power.”

Current computers use random access memory (RAM), which moves very quickly as a user works but does not retain unsaved data if power is lost. Flash drives, on the other hand, store information when they are not powered but work much slower. Memristors could provide a memory that is the best of both worlds: fast and reliable. But there’s a problem: memristors are two-terminal electronic devices, which can only control one voltage channel. Hersam wanted to transform it into a three-terminal device, allowing it to be used in more complex electronic circuits and systems.

The memristor is of some interest to a number of other parties prominent amongst them, the University of Michigan’s Professor Wei Lu and HP (Hewlett Packard) Labs, both of whom are mentioned in one of my more recent memristor pieces, a June 26, 2014 post.

Getting back to Northwestern,

Hersam and his team met this challenge by using single-layer molybdenum disulfide (MoS2), an atomically thin, two-dimensional nanomaterial semiconductor. Much like the way fibers are arranged in wood, atoms are arranged in a certain direction–called “grains”–within a material. The sheet of MoS2 that Hersam used has a well-defined grain boundary, which is the interface where two different grains come together.

“Because the atoms are not in the same orientation, there are unsatisfied chemical bonds at that interface,” Hersam explained. “These grain boundaries influence the flow of current, so they can serve as a means of tuning resistance.”

When a large electric field is applied, the grain boundary literally moves, causing a change in resistance. By using MoS2 with this grain boundary defect instead of the typical metal-oxide-metal memristor structure, the team presented a novel three-terminal memristive device that is widely tunable with a gate electrode.

“With a memristor that can be tuned with a third electrode, we have the possibility to realize a function you could not previously achieve,” Hersam said. “A three-terminal memristor has been proposed as a means of realizing brain-like computing. We are now actively exploring this possibility in the laboratory.”

Here’s a link to and a citation for the paper,

Gate-tunable memristive phenomena mediated by grain boundaries in single-layer MoS2 by Vinod K. Sangwan, Deep Jariwala, In Soo Kim, Kan-Sheng Chen, Tobin J. Marks, Lincoln J. Lauhon, & Mark C. Hersam. Nature Nanotechnology (2015) doi:10.1038/nnano.2015.56 Published online 06 April 2015

This paper is behind a paywall but there is a few preview available through ReadCube Access.

Dexter Johnson has written about this latest memristor development in an April 9, 2015 posting on his Nanoclast blog (on the IEEE [Institute for Electrical and Electronics Engineers] website) where he notes this (Note: A link has been removed),

The memristor seems to generate fairly polarized debate, especially here on this website in the comments on stories covering the technology. The controversy seems to fall along the lines that the device that HP Labs’ Stan Williams and Greg Snider developed back in 2008 doesn’t exactly line up with the original theory of the memristor proposed by Leon Chua back in 1971.

It seems the ‘debate’ has evolved from issues about how the memristor is categorized. I wonder if there’s still discussion about whether or not HP Labs is attempting to develop a patent thicket of sorts.

Gender gaps in science and how statistics prove and disprove the finding

A Feb. 17, 2015 Northwestern University news release by Hilary Hurd Anyaso (also on EurekAlert) features research suggesting that parity in the numbers of men and women students pursuing science degrees is being achieved,

Scholars from diverse fields have long proposed that interlocking factors such as cognitive abilities, discrimination and interests may cause more women than men to leave the science, technology, engineering and mathematics (STEM) pipeline after entering college.

Now a new Northwestern University analysis has poked holes in the much referenced “leaky pipeline” metaphor.

The research shows that the bachelor’s-to-Ph.D. pipeline in science and engineering fields no longer leaks more women than men as it did in the past

Curt Rice, a professor at Norway’s University of Tromsø, has challenged the findings in a Feb. 18, 2015 post on his eponymous website (more about that later).

The news release goes on to describe how the research was conducted and the conclusions researchers drew from the data,

The researchers used data from two large nationally representative research samples to reconstruct a 30-year portrait of how bachelor’s-to-Ph.D. persistence rates for men and women have changed in the United States since the 1970s. For this study, the term STEM persistence rate refers to the proportion of students who earned a Ph.D. in a particular STEM field (e.g. engineering) among students who had earlier received bachelor’s degrees in that same field.

They were particularly surprised that the gender persistence gap completely closed in pSTEM fields (physical science, technology, engineering and mathematics) — the fields in which women are most underrepresented.

Among students earning pSTEM bachelor’s degrees in the 1970s, men were 1.6 to 1.7 times as likely as women to later earn a pSTEM Ph.D. However, this gap completely closed by the 1990s.

Men still outnumber women by approximately three to one among pSTEM Ph.D. earners. But those differences in representation are not explained by differences in persistence from the bachelor’s to Ph.D. degree, said David Miller, an advanced doctoral student in psychology at Northwestern and lead author of the study.

“Our analysis shows that women are overcoming any potential gender biases that may exist in graduate school or undergraduate mentoring about pursing graduate school,” Miller said. “In fact, the percentage of women among pSTEM degree earners is now higher at the Ph.D. level than at the bachelor’s, 27 percent versus 25 percent.”

Jonathan Wai, a Duke University Talent Identification Program research scientist and co-author of the study, said a narrowing of gender gaps makes sense given increased efforts to promote gender diversity in science and engineering.

“But a complete closing of the gap was unexpected, especially given recent evidence of gender bias in science mentoring,” Wai said.

Consequently, the widely used leaky pipeline metaphor is a dated description of gender differences in postsecondary STEM education, Wai added.

Other research shows that gaps in persistence rates are also small to nonexistent past the Ph.D., Miller said.

“For instance, in physical science and engineering fields, male and female Ph.D. holders are equally likely to earn assistant professorships and academic tenure,” Miller said.

The leaky pipeline metaphor is inaccurate for nearly all postsecondary pathways in STEM, Miller said, with two important exceptions.

“The Ph.D.-to-assistant-professor pipeline leaks more women than men in life science and economics,” he said. “Differences in those fields are large and important.”

The implications of the research, Miller said, are important in guiding research, resources and strategies to explain and change gender imbalances in science.

“The leaking pipeline metaphor could potentially direct thought and resources away from other strategies that could more potently increase women’s representation in STEM,” he said.

For instance, plugging leaks in the pipeline from the beginning of college to the bachelor’s degree would fail to substantially increase women’s representation among U.S. undergraduates in the pSTEM fields, Miller said.

Of concern, women’s representation among pSTEM bachelor’s degrees has been decreasing during the past decade, Miller noted. “Our analyses indicate that women’s representation at the Ph.D. level is starting to follow suit by declining for the first time in over 40 years,” he said.

“This recent decline at the Ph.D. level could likely mean that women’s progress at the assistant professor level might also slow down or reverse in future years, so these trends will need to be watched closely,” Wai said.

While the researchers are encouraged that gender gaps in doctoral persistence have closed, they stressed that accurately assessing and changing gender biases in science should remain an important goal for educators and policy makers.

Before moving on to Rice’s comments, here’s a link to and citation for the paper,

The bachelor’s to Ph.D. STEM pipeline no longer leaks more women than men: a 30-year analysis by David I. Miller and Jonathan Wai. Front. Psychol., 17 February 2015, doi: 10.3389/fpsyg.2015.00037

This paper is open access (at least for now).

Maybe the situation isn’t improving after all

Curt Rice’s response titled, The incontinent pipeline: it’s not just women leaving higher education, suggests this latest research has unmasked a problem (Note: Links have been removed),

Freshly published research gives a more nuanced picture. The traditional recitation of percentages at various points along the pipeline provides a snapshot. The new research is more like a time-lapse film.

Unfortunately, the new study doesn’t actually show a pipeline being tightened up to leak less. Instead, it shows a pipeline that is leaking even more! The convergence in persistence rates for men and women is not a result of an increase in the rate of women taking a PhD; it’s the result of a decline in the rate of men doing so. It’s as though the holes have gotten bigger — they used to be so small that only women slipped through, but now men slide out, too.

Rice believes  that this improvement is ‘relative improvement’ i.e. the improvement exists in relation to declining numbers of men, a statistic that Rice gives more weight to than the Northwestern researchers appear to have done. ‘Absolute improvement’ would mean that numbers of women studying in the field had improved while men’s numbers had held steady or improved for them too.

To be fair, the authors of the paper seem to have taken at least some of this decline in men’s numbers into account (from the research paper),,

Reasons for the convergences in persistence rates remain unclear. Sometimes the convergence was driven by declines in men’s rates (e.g., in mathematics/computer science), increases in women’s rates (e.g., in physical science), or both (e.g., in engineering). help account for the changes in persistence rates. …

Overenthusiasm in the news release

Unfortunately, the headline and bullet list of highlights suggest a more ebullient research conclusion than seems warranted by the actual research results.

Think again about gender gap in science
Bachelor’s-to-Ph.D. pipeline in science, engineering no longer ‘leaks’ more women than men, new 30-year analysis finds

Research shows dated ‘leaky pipeline’ assumptions about gender imbalances in science

  • Men outnumber women as Ph.D. earners in science but no longer in doctoral persistence
  • Dramatic increase of women in science at Ph.D., assistant professorship levels since 1970s, but recent decline since 2010 may be of concern for future supply of female scientists
  • Assessing inaccurate assumptions key to correcting gender biases in science

Here’s the researchers’ conclusion,

Overall, these results and supporting literature point to the need to understand gender differences at the bachelor’s level and below to understand women’s representation in STEM at the Ph.D. level and above. Women’s representation in computer science, engineering, and physical science (pSTEM) fields has been decreasing at the bachelor’s level during the past decade. Our analyses indicate that women’s representation at the Ph.D. level is starting to follow suit by declining for the first time in over 40 years (Figure 2). This recent decline may also cause women’s gains at the assistant professor level and beyond to also slow down or reverse in the next few years. Fortunately, however, pathways for entering STEM are considerably diverse at the bachelor’s level and below. For instance, our prior research indicates that undergraduates who join STEM from a non-STEM field can substantially help the U.S. meet needs for more well-trained STEM graduates (Miller et al., under review). Addressing gender differences at the bachelor’s level could have potent effects at the Ph.D. level, especially now that women and men are equally likely to later earn STEM Ph.D.’s after the bachelor’s.

The conclusion seems to contradict the researchers’ statements in the news release,

“But a complete closing of the gap was unexpected, especially given recent evidence of gender bias in science mentoring,” Wai said.

Consequently, the widely used leaky pipeline metaphor is a dated description of gender differences in postsecondary STEM education, Wai added.

Other research shows that gaps in persistence rates are also small to nonexistent past the Ph.D., Miller said.

Incomplete pipeline

Getting back to Rice, he notes the pipeline in the Northwestern paper is incomplete (Note: Links have been removed),

In addition to the dubious celebration of the decline of persistence rates of men, the new research article also looks at an incomplete pipeline. In particular, it leaves aside the important issue of which PhD institutions students get into. For young researchers moving towards academic careers, we know that a few high-prestige universities are responsible for training future faculty members at nearly all other research universities. Are women and men getting into those high prestige universities in the same numbers? Or do women go to lower prestige institutions?

Following on that thought about lower prestige institutions and their impact on your career, there’s a Feb. 23, 2015 article by Joel Warner and Aaron Clauset in Slate investigating the situation, which applies to both men and women,

The United States prides itself on offering broad access to higher education, and thanks to merit-based admissions, ample financial aid, and emphasis on diverse student bodies, our country can claim some success in realizing this ideal.

The situation for aspiring professors is far grimmer. Aaron Clauset, a co-author of this article, is the lead author of a new study published in Science Advances that scrutinized more than 16,000 faculty members in the fields of business, computer science, and history at 242 schools. He and his colleagues found, as the paper puts it, a “steeply hierarchical structure that reflects profound social inequality.” The data revealed that just a quarter of all universities account for 71 to 86 percent of all tenure-track faculty in the U.S. and Canada in these three fields. Just 18 elite universities produce half of all computer science professors, 16 schools produce half of all business professors, and eight schools account for half of all history professors.

Then, Warner and Clauset said this about gender bias,

Here’s further evidence that the current system isn’t merely sorting the best of the best from the merely good. Female graduates of elite institutions tend to slip 15 percent further down the academic hierarchy than do men from the same institutions, evidence of gender bias to go along with the bias toward the top schools.

I suggest reading the Slate article, Rice’s post, and, if you have time, the Northwestern University research paper.

Coda: All about Curt Rice

Finally, this is for anyone who’s unfamiliar with Curt Rice (from the About page on his website; Note: Links have been removed),

In addition to my work as a professor at the University of Tromsø, I have three other roles that are closely related to the content on this website. I was elected by the permanent faculty to sit on the university board, I lead Norway’s Committee on Gender Balance and Diversity in Research, and I am the head of the Board for Current Research Information System in Norway (CRIStin). In all of these roles, I work to pursue my conviction that research and education are essential to improving society, and that making universities better therefore has the potential to make societies better.

I’m currently writing a book on gender balance. Why do men and women have different career paths? Why should we care? How can we start to make things better? Why is improving gender balance not only the right thing to do, but also the smart thing to do? For a taste of my approach, grab a copy of my free ebook on gender equality.

Beyond this book project, I use my speaking and writing engagements to reach audiences on the topics that excite me the most: gender balance, open access, leadership issues and more. These interests have grown during the past decade while I’ve had the privilege to occupy what were then two brand new leadership positions at the University of Tromsø.

From 2009–2013, I served as the elected Vice Rector for Research & Development (prorektor for forskning og utvikling). Before that, from 2002–2008, I was the founding director of my university’s first Norwegian Center of Excellence, the Center for Advanced Study in Theoretical Linguistics (CASTL). Given the luxury of being able to define those positions, I was able to pursue my passion for improving academic life by working to enhance conditions for education and research.

I’m part of the European Science Foundation’s genderSTE COST action (Gender, Science, Technology and Environment); I helped create the BALANSE program at the Research Council of Norway, which is designed to increase the numbers of women at the highest levels of research organizations. I am on the Advisory Board of the European Commission project EGERA (Effective Gender Equality in Research and Academia); I was on the Science Leaders Panel of the genSET project, in which we advised the European Commission about gender in science; I am a member of the Steering Committee for the Gender Summits.

I also led a national task force on research-based education that issued many suggestions for Norwegian institutions.

Bypassing nanofabrication methods for colourful silver

A new technique developed by researchers at Northwestern University (Chicago, US) would be faster and cheaper than nanofabrication methods according to a Feb. 14, 2015 news item on Azonano,

Northwestern University researchers have created a new technique that can transform silver into any color of the rainbow. Their simple method is a fast, low-cost alternative to color filters currently used in electronic displays and monitors.

“Our technique doesn’t require expensive nanofabrication techniques or a lot of materials,” said Koray Aydin, assistant professor of electrical engineering and computer science at the McCormick School of Engineering. “And it can be completed in a half hour or so.”

A Feb. 12, 2015 Northwestern University news release (also on EurekAlert but dated Feb. 13, 2015), which originated the news item, provides more details about the research,

The filter’s secret lies within its “sandwich-like” structure. Aydin and his team created a three-layer design, where glass is wedged two thin layers of silver film. The silver layers are thin enough to allow optical light to pass through, which then transmits a certain color through the glass and reflects the rest of the visible spectrum. By changing the thickness of the glass, Aydin was able to filter and produce different colors.

“Controlling the thickness of the glass controls the color,” Aydin said. “This way, we can create any color desired.”

By making the bottom silver layer even thicker, Aydin found that the structure also acts as a color absorber because it traps light between the two metal layers. The team demonstrated a narrow bandwidth super absorber with 97 percent maximum absorption, which could have potential applications for optoelectric devices with controlled bandwidth, such as narrow-band photodetectors and light-emitting devices. The performance of Aydin’s structure is comparable to that of nanostructure-based devices but bypasses the complications of nanotechnology.

“People in the nanophotonics community are dealing with nanostructures, making nanoparticles, and using lithography or chemistry techniques,” he said. “That can be really challenging. We’re combatting that difficulty with a simple design.”

Aydin is also developing a similar structure out of aluminum and glass to filter or absorb ultraviolet spectrum. By controlling the thickness of the materials, he plans to design devices for other wavelengths of light.

Here’s a link to and a citation for the paper,

Large-Area, Lithography-Free Super Absorbers and Color Filters at Visible Frequencies Using Ultrathin Metallic Films by Zhongyang Li, Serkan Butun, and Koray Aydin. ACS Photonics, Article ASAP DOI: 10.1021/ph500410u Publication Date (Web): January 28, 2015
Copyright © 2015 American Chemical Society

This paper is behind a paywall.

Bipolar disorder at the nanoscale

In all the talk generated by the various brain projects (BRAIN initiative [US], The Human Brain Project [European Union], Brain Canada), there’s remarkably little discussion about mental illness. So, this news is a little unusual.

Using super-high resolution technique scientists at Northwestern University (Chicago, Illinois, US) believe they’ve made a discovery which explains how bipolar disorder affects the brain according to an Oct. 22, 2014 Northwestern University news release (also on EurekAlert and ScienceDaily) by Erin White,

Scientists used a new super-resolution imaging method — the same method recognized with the 2014 Nobel Prize in chemistry — to peer deep into brain tissue from mice with bipolar-like behaviors. In the synapses (where communication between brain cells occurs), they discovered tiny “nanodomain” structures with concentrated levels of ANK3 — the gene most strongly associated with bipolar disorder risk. ANK3 is coding for the protein ankyrin-G.

“We knew that ankyrin-G played an important role in bipolar disease, but we didn’t know how,” said Northwestern Medicine scientist Peter Penzes, corresponding author of the paper. “Through this imaging method we found the gene formed in nanodomain structures in the synapses, and we determined that these structures control or regulate the behavior of synapses.”

Penzes is a professor in physiology and psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine. The results were published Oct. 22 in the journal Neuron.

High-profile cases, including actress Catherine Zeta-Jones and politician Jesse Jackson, Jr., have brought attention to bipolar disorder. The illness causes unusual shifts in mood, energy, activity levels and the ability to carry out day-to-day tasks. About 3 percent of Americans experience bipolar disorder symptoms, and there is no cure.

Recent large-scale human genetic studies have shown that genes can contribute to disease risk along with stress and other environmental factors. However, how these risk genes affect the brain is not known.

This is the first time any psychiatric risk gene has been analyzed at such a detailed level of resolution. As explained in the paper, Penzes used the Nikon Structured Illumination Super-resolution Microscope to study a mouse model of bipolar disorder. The microscope realizes resolution of up to 115 nanometers. To put that size in perspective, a nanometer is one-tenth of a micron, and there are 25,400 microns in one inch. Very few of these microscopes exist worldwide.

“There is important information about genes and diseases that can only been seen at this level of resolution,” Penzes said. “We provide a neurobiological explanation of the function of the leading risk gene, and this might provide insight into the abnormalities in bipolar disorder.”

The biological framework presented in this paper could be used in human studies of bipolar disorder in the future, with the goal of developing therapeutic approaches to target these genes.

Here’s a link to and a citation for the paper,

Psychiatric Risk Factor ANK3/Ankyrin-G Nanodomains Regulate the Structure and Function of Glutamatergic Synapses by Katharine R. Smith, Katherine J. Kopeikina, Jessica M. Fawcett-Patel, Katherine Leaderbrand, Ruoqi Gao, Britta Schürmann, Kristoffer Myczek, Jelena Radulovic, Geoffrey T. Swanson, and Peter Penzes. Neuron, Volume 84, Issue 2, p399–415, 22 October 2014 DOI: http://dx.doi.org/10.1016/j.neuron.2014.10.010

This paper is behind a paywall.

You can find more about super-high resolution and nanoscopy in my Oct. 8, 2014 post about the 2014 Nobel Chemistry prize winners.

‘Genius’ grant (MacArthur Fellowship) for reseacher Mark Hersam and his work on carbon nanotubes and the next generation of electronics

It took a few minutes to figure out why Mark Hersam, professor at Northwestern University (Chicago, Illinois, US) is being featured in an Oct. 21, 2014 news item on Nanowerk,

One of the longstanding problems of working with nanomaterials–substances at the molecular and atomic scale–is controlling their size. When their size changes, their properties also change. This suggests that uniform control over size is critical in order to use them reliably as components in electronics.

Put another way, “if you don’t control size, you will have inhomogeneity in performance,” says Mark Hersam. “You don’t want some of your cell phones to work, and others not.”

Hersam, a professor of materials science engineering, chemistry and medicine at Northwestern University, has developed a method to separate nanomaterials by size, therefore providing a consistency in properties otherwise not available. Moreover, the solution came straight from the life sciences–biochemistry, in fact.

The technique, known as density gradient ultracentrifugation, is a decades-old process used to separate biomolecules. The National Science Foundation (NSF)-funded scientist theorized correctly that he could adapt it to separate carbon nanotubes, rolled sheets of graphene (a single atomic layer of hexagonally bonded carbon atoms), long recognized for their potential applications in computers and tablets, smart phones and other portable devices, photovoltaics, batteries and bioimaging.

The technique has proved so successful that Hersam and his team now hold two dozen pending or issued patents, and in 2007 established their own company, NanoIntegris, jump-started with a $150,000 NSF small business grant. The company has been able to scale up production by 10,000-fold, and currently has 700 customers in 40 countries.
“We now have the capacity to produce ten times the worldwide demand for this material,” Hersam says.

NSF supports Hersam with a $640,000 individual investigator grant awarded in 2010 for five years. Also, he directs Northwestern’s Materials Research Science and Engineering Center (MRSEC), which NSF funds, including support for approximately 30 faculty members/researchers.

Hersam also is a recent recipient of one of this year’s prestigious MacArthur fellowships, a $625,000 no-strings-attached award, popularly known as a “genius” grant. [emphases mine] These go to talented individuals who have shown extraordinary originality and dedication in their fields, and are meant to encourage beneficiaries to freely explore their interests without fear of risk-taking.

An Oct. 20, 2014 US National Science Foundation Discoveries article by Marlene Cimons, which originated the news item, describes Hersam’s research and his hopes for it in more detail,

The carbon nanotubes separation process, which Hersam developed, begins with a centrifuge tube. Into that, “we load a water based solution and introduce an additive which allows us to tune the buoyant density of the solution itself,” he explains.

“What we create is a gradient in the buoyant density of the aqueous solution, with low density at the top and high density at the bottom,” he continues. “We then load the carbon nanotubes and put it into the centrifuge, which drives the nanotubes through the gradient. The nanotubes move through the gradient until their density matches that of the gradient. The result is that the nanotubes form separated bands in the centrifuge tube by density. Since the density of the nanotube is a function of its diameter, this method allows separation by diameter.”

One property that distinguishes these materials from traditional semiconductors like silicon is that they are mechanically flexible. “Carbon nanotubes are highly resilient,” Hersam says. “That allows us to integrate electronics on flexible substrates, like clothing, shoes, and wrist bands for real time monitoring of biomedical diagnostics and athletic performance. These materials have the right combination of properties to realize wearable electronics.”

He and his colleagues also are working on energy technologies, such as solar cells and batteries “that can improve efficiency and reduce the cost of solar cells, and increase the capacity and reduce the charging time of batteries,” he says. “The resulting batteries and solar cells are also mechanically flexible, and thus can be integrated with flexible electronics.”

They likely even will prove waterproof. “It turns out that carbon nanomaterials are hydrophobic, so water will roll right off of them,” he says.

A Sept. 17, 2014 Northwestern University news release congratulates Hersam on his award while describing his response to the news and providing more information about his work as a researcher and teacher (Note: Links have been removed),

The phone call from the John D. and Catherine T. MacArthur Foundation delivering the very good news was so out of the blue that Hersam initially thought it was a joke.

“Then I went into shock, and, I think, to some extent I remain in shock,” said Hersam, who received the call in his Cook Hall office. “As time has gone on, I’ve appreciated, of course, that it’s a great honor and, more importantly, a great opportunity.”

A dedicated and popular teacher, Hersam is the Bette and Neison Harris Chair in Teaching Excellence and professor of materials science and engineering at the McCormick School of Engineering and Applied Science.

“There are very few awards that provide unrestricted resources, and this one does. No strings attached,” he said. “That’s a great opportunity for a researcher — to have that level of freedom.”

Hersam is one of 21 new MacArthur Fellows recognized today (Sept. 17) by the MacArthur Foundation for “extraordinary originality and dedication in their creative pursuits and a marked capacity for self-direction.”

“I am very grateful and thankful to the MacArthur Foundation, to current and previous members of my research group and to my colleagues and collaborators over the years,” Hersam said. “Scientific research is a team effort.”

Hersam views his principal job as that of an educator — a role in which he can have more impact on unsolved problems by harnessing the minds of hundreds of young scientists and engineers.

“I love to teach in the classroom, but I also believe that scientific research is a vehicle for teaching,” Hersam said. “Research exposes students to difficult unsolved problems, forcing them to be creative. I want them to come up with truly new ideas, not just regurgitate established concepts.”

Hersam, who joined Northwestern in 2000, also is professor of chemistry in the Weinberg College of Arts and Sciences, professor of medicine at the Northwestern University Feinberg School of Medicine and director of Northwestern’s Materials Research Center.

Taking an interdisciplinary approach that draws on techniques from materials science, physics, engineering and chemistry, Hersam has established himself as a leading experimentalist in the area of hybrid organic-inorganic materials, with a focus on the study of the electrical and optical properties of carbon and related nanomaterials.

Hersam and his research lab have been working primarily with carbon nanotubes and graphene, but the support of the MacArthur award will allow the lab to diversify its materials set to other elements in the periodic table.

Earlier this year Hersam testified before U.S. Congress to push for “coordinated, predictable and sustained federal funding” for nanotechnology research and development.

The MacArthur Foundation’s website hosts a video on its ‘Mark Hersam’ webpage,

Interestingly, Hersam, in the video, describes a carbon nanotube as a rolled up sheet of graphene (it’s also described that way on the Foundation’s ‘Hersam’ webpage),

Graphene, a single atomic layer of hexagonally bonded carbon atoms, and carbon nanotubes, rolled sheets of graphene in single or multiple layers, have long been recognized for their potential applications in electronics, photovoltaics, batteries, and bioimaging.

It’s a good way of describing carbon nanotubes but the odd thing is that carbon nanotubes were discovered in 1991 (Timeline of carbon nanotubes entry on Wikipedia and in The History of Carbon Nanotubes on nanogloss.com) before graphene was first isolated in 2004 (my Oct. 7, 2010 posting).

E-tattoo without the nanotech

John Rogers and his team at the University of Illinois and a colleague’s (Yonggang Huang) team at Northwestern University have devised an ‘electronic tattoo’ (a soft, stick-on patch) made up from materials that anyone can purchase off-the-shelf. Rogers is known for his work with nanomaterials (my Aug. 10, 2012 posting titled ‘Surgery with fingertip control‘ mentioned a silicon nanomembrane that can be fitted onto the fingertips for possible use in surgical procedures) and with electronics (my Aug. 12, 2011 posting titled: ‘Electronic tattoos‘ mentioned his earlier attempts at developing e-tattoos).

This latest effort from Rogers and his multi-university team is mentioned in an April 4, 2014 article by Mark Wilson for Fast Company,

About a year ago, University of Illinois researcher John Rogers revealed a pretty amazing creation: a circuit that, rather than living on an inflexible board, could stick to and move with someone’s skin just like an ink stamp. But like any early research, it was mostly a proof-of-concept, and it would require relatively expensive, custom-printed electronics to work.

Today, Rogers, in conjunction with Northwestern University’s Yonggang Huang, has published details on version 2.0 in Science, revealing that this once-esoteric project has more immediate, mass market appeal.

… It means that you could create a wearable electronic that’s one-part special sticky circuit board, every other part whatever-the-hell-you-manufactured-in-China. This flexible circuit could accommodate a stock battery, an accelerometer, a Wi-Fi chip, and a Bluetooth circuitry, for instance, all living on your skin rather than inside your iPhone. And as an added bonus, it would be relatively cheap.

A University of Illinois April ?, 2014 news release describes Rogers, his multi-university team, and their current (pun intended) e-tattoo,

Engineers at the University of Illinois at Urbana-Champaign and Northwestern University have demonstrated thin, soft stick-on patches that stretch and move with the skin and incorporate commercial, off-the-shelf chip-based electronics for sophisticated wireless health monitoring.

The patches stick to the skin like a temporary tattoo and incorporate a unique microfluidic construction with wires folded like origami to allow the patch to bend and flex without being constrained by the rigid electronics components. The patches could be used for everyday health tracking – wirelessly sending updates to your cellphone or computer – and could revolutionize clinical monitoring such as EKG and EEG testing – no bulky wires, pads or tape needed.

“We designed this device to monitor human health 24/7, but without interfering with a person’s daily activity,” said Yonggang Huang, the Northwestern University professor who co-led the work with Illinois professor John A. Rogers. “It is as soft as human skin and can move with your body, but at the same time it has many different monitoring functions. What is very important about this device is it is wirelessly powered and can send high-quality data about the human body to a computer, in real time.”

The researchers did a side-by-side comparison with traditional EKG and EEG monitors and found the wireless patch performed equally to conventional sensors, while being significantly more comfortable for patients. Such a distinction is crucial for long-term monitoring, situations such as stress tests or sleep studies when the outcome depends on the patient’s ability to move and behave naturally, or for patients with fragile skin such as premature newborns.

Rogers’ group at Illinois previously demonstrated skin electronics made of very tiny, ultrathin, specially designed and printed components. While those also offer high-performance monitoring, the ability to incorporate readily available chip-based components provides many important, complementary capabilities in engineering design, at very low cost.

“Our original epidermal devices exploited specialized device geometries – super thin, structured in certain ways,” Rogers said. “But chip-scale devices, batteries, capacitors and other components must be re-formulated for these platforms. There’s a lot of value in complementing this specialized strategy with our new concepts in microfluidics and origami interconnects to enable compatibility with commercial off-the-shelf parts for accelerated development, reduced costs and expanded options in device types.”

The multi-university team turned to soft microfluidic designs to address the challenge of integrating relatively big, bulky chips with the soft, elastic base of the patch. The patch is constructed of a thin elastic envelope filled with fluid. The chip components are suspended on tiny raised support points, bonding them to the underlying patch but allowing the patch to stretch and move.

One of the biggest engineering feats of the patch is the design of the tiny, squiggly wires connecting the electronics components – radios, power inductors, sensors and more. The serpentine-shaped wires are folded like origami, so that no matter which way the patch bends, twists or stretches, the wires can unfold in any direction to accommodate the motion. Since the wires stretch, the chips don’t have to.

Skin-mounted devices could give those interested in fitness tracking a more complete and accurate picture of their activity level.

“When you measure motion on a wristwatch type device, your body is not very accurately or reliably coupled to the device,” said Rogers, a Swanlund Professor of Materials Science and Engineering at the U. of I. “Relative motion causes a lot of background noise. If you have these skin-mounted devices and an ability to locate them on multiple parts of the body, you can get a much deeper and richer set of information than would be possible with devices that are not well coupled with the skin. And that’s just the beginning of the rich range of accurate measurements relevant to physiological health that are possible when you are softly and intimately integrated onto the skin.”

The researchers hope that their sophisticated, integrated sensing systems could not only monitor health but also could help identify problems before the patient may be aware. For example, according to Rogers, data analysis could detect motions associated with Parkinson’s disease at its onset.

“The application of stretchable electronics to medicine has a lot of potential,” Huang said. “If we can continuously monitor our health with a comfortable, small device that attaches to our skin, it could be possible to catch health conditions before experiencing pain, discomfort and illness.”

Here’s a link to and a citation for the paper,

Soft Microfluidic Assemblies of Sensors, Circuits, and Radios for the Skin by Sheng Xu, Yihui Zhang, Lin Jia, Kyle E. Mathewson, Kyung-In Jang, Jeonghyun Kim, Haoran Fu, Xian Huang, Pranav Chava, Renhan Wang, Sanat Bhole, Lizhe Wang, Yoon Joo Na, Yue Guan, Matthew Flavin, Zheshen Han, Yonggang Huang, & John A. Rogers. Science 4 April 2014: Vol. 344 no. 6179 pp. 70-74 DOI: 10.1126/science.1250169

This paper is behind a paywall.

Richard Van Duyne solves mystery of Renoir’s red with surface-enhanced Raman spectroscopy (SERS) and Canadian scientists uncover forgeries

The only things these two items have in common is that they are concerned with visual art. and with solving mysteries The first item concerns research by Richard Van Duyne into the nature of the red paint used in one of Renoir’s paintings. A February 14, 2014 news item on Azonano describes some of the art conservation work that Van Duyne’s (nanoish) technology has made possible along with details about this most recent work,

Scientists are using powerful analytical and imaging tools to study artworks from all ages, delving deep below the surface to reveal the process and materials used by some of the world’s greatest artists.

Northwestern University chemist Richard P. Van Duyne, in collaboration with conservation scientists at the Art Institute of Chicago, has been using a scientific method he discovered nearly four decades ago to investigate masterpieces by Pierre-Auguste Renoir, Winslow Homer and Mary Cassatt.

Van Duyne recently identified the chemical components of paint, now partially faded, used by Renoir in his oil painting “Madame Léon Clapisson.” Van Duyne discovered the artist used carmine lake, a brilliant but light-sensitive red pigment, on this colorful canvas. The scientific investigation is the cornerstone of a new exhibition at the Art Institute of Chicago.

The Art Institute of Chicago’s exhibition is called, Renoir’s True Colors: Science Solves a Mystery. being held from Feb. 12, 2014 – April 27, 2014. Here is an image of the Renoir painting in question and an image featuring the equipment being used,

Renoir-Madame-Leon-Clapisson.Art Institute of Chicago.

Renoir-Madame-Leon-Clapisson.Art Institute of Chicago.

Renoir and surface-enhanced Raman spectroscopy (SERS). Art Institute of Chicago

Renoir and surface-enhanced Raman spectroscopy (SERS). Art Institute of Chicago

The Feb. 13, 2014 Northwestern University news release (also on EurekAlert) by Megan Fellman, which originated the news item, gives a brief description of Van Duyne’s technique and its impact on conservation at the Art Institute of Chicago (Note: A link has been removed),

To see what the naked eye cannot see, Van Duyne used surface-enhanced Raman spectroscopy (SERS) to uncover details of Renoir’s paint. SERS, discovered by Van Duyne in 1977, is widely recognized as the most sensitive form of spectroscopy capable of identifying molecules.

Van Duyne and his colleagues’ detective work informed the production of a new digital visualization of the painting’s original colors by the Art Institute’s conservation department. The re-colorized reproduction and the original painting (presented in a case that offers 360-degree views) can be viewed side by side at the exhibition “Renoir’s True Colors: Science Solves a Mystery” through April 27 [2014] at the Art Institute.

I first wrote about Van Duyne’s technique in my wiki, The NanoTech Mysteries. From the Scientists get artful page (Note: A footnote was removed),

Richard Van Duyne, then a chemist at Northwestern University, developed the technique in 1977. Van Duyne’s technology, based on Raman spectroscopy which has been around since the 1920s, is called surface-enhanced Raman spectroscopy’ or SERS “[and] uses laser light and nanoparticles of precious metals to interact with molecules to show the chemical make-up of a particular dye.”

This next item is about forgery detection. A March 5, 2014 news release on EurekAlert describes the latest developments,

Gallery owners, private collectors, conservators, museums and art dealers face many problems in protecting and evaluating their collections such as determining origin, authenticity and discovery of forgery, as well as conservation issues. Today these problems are more accurately addressed through the application of modern, non-destructive, “hi-tech” techniques.

Dmitry Gavrilov, a PhD student in the Department of Physics at the University of Windsor (Windsor, Canada), along with Dr. Roman Gr. Maev, the Department of Physics Professor at the University of Windsor (Windsor, Canada) and Professor Dr. Darryl Almond of the University of Bath (Bath, UK) have been busy applying modern techniques to this age-old field. Infrared imaging, thermography, spectroscopy, UV fluorescence analysis, and acoustic microscopy are among the innovative approaches they are using to conduct pre-restoration analysis of works of art. Some fascinating results from their applications are published today in the Canadian Journal of Physics.

Since the early 1900s, using infrared imaging in various wave bands, scientists have been able to see what parts of artworks have been retouched or altered and sometimes even reveal the artist’s original sketches beneath layers of the paint. Thermography is a relatively new approach in art analysis that allows for deep subsurface investigation to find defects and past reparations. To a conservator these new methods are key in saving priceless works from further damage.

Gavrilov explains, “We applied new approaches in processing thermographic data, materials spectra data, and also the technique referred to as craquelure pattern analysis. The latter is based on advanced morphological processing of images of surface cracks. These cracks, caused by a number of factors such as structure of canvas, paints and binders used, can uncover important clues on the origins of a painting.”

“Air-coupled acoustic imaging and acoustic microscopy are other innovative approaches which have been developed and introduced into art analysis by our team under supervision of Dr. Roman Gr. Maev. The technique has proven to be extremely sensitive to small layer detachments and allows for the detection of early stages of degradation. It is based on the same principles as medical and industrial ultrasound, namely, the sending a sound wave to the sample and receiving it back. ”

Spectroscopy is a technique that has been useful in the fight against art fraud. It can determine chemical composition of pigments and binders, which is essential information in the hands of an art specialist in revealing fakes. As described in the paper, “…according to the FBI, the value of art fraud, forgery and theft is up to $6 billion per year, which makes it the third most lucrative crime in the world after drug trafficking and the illegal weapons trade.”

One might wonder how these modern applications can be safe for delicate works of art when even flash photography is banned in art galleries. The authors discuss this and other safety concerns, describing both historic and modern-day implications of flash bulbs and exhibit illumination and scientific methods. As the paper concludes, the authors suggest that we can expect that the number of “hi-tech” techniques will only increase. In the future, art experts will likely have a variety of tools to help them solve many of the mysteries hiding beneath the layers.

Here’s a link to and a citation for the paper,

A review of imaging methods in analysis of works of art: Thermographic imaging method in art analysis by D. Gavrilov, R.Gr. Maev, and D.P. Almond. Canadian Journal of Physics, 10.1139/cjp-2013-0128

This paper is open access.

‘Giving’ life to liquid crystals

A Feb. 18, 2014 news item on Azonano highlights a presentation about living liquid crystals that was given at the 58th annual Biophysical Society Meeting in San Francisco on Feb. 17, 2014,

Plop living, swimming bacteria into a novel water-based, nontoxic liquid crystal and a new physics takes over. The dynamic interaction of the bacteria with the liquid crystal creates a novel form of soft matter: living liquid crystal.

The new type of active material, which holds promise for improving the early detection of diseases, was developed by a research collaboration based at Ohio’s Kent State University and Illinois’ Argonne National Laboratory. The team will present their work at the 58th annual Biophysical Society Meeting, held in San Francisco, Feb.15-19 [2014].

ScienceDaily featured the story in a Feb. 17, 2014 news item,

As a biomechanical hybrid, living liquid crystal moves and reshapes itself in response to external stimuli. It also stores energy just as living organisms do to drive its internal motion. And it possesses highly desirable optical properties. In a living liquid crystal system, with the aid of a simple polarizing microscope, you can see with unusual clarity the wake-like trail stimulated by the rotation of bacterial flagella just 24-nanometers thick, about 1/4000th the thickness of an average human hair.

You can also control and guide active movements of the bacteria by manipulating variables such as oxygen availability, temperature or surface alignment, thus introducing a new design concept for creating microfluidic biological sensors. Living liquid crystal provides a medium to amplify tiny reactions that occur at the micro- and nano-scales — where molecules and viruses interact — and to also easily optically detect and analyze these reactions. That suits living liquid crystal to making sensing devices that monitor biological processes such as cancer growth, or infection. Such microfluidic technology is of increasing importance to biomedical sensing as a means of detecting disease in its earliest stages when it is most treatable, and most cost-effectively managed.

Quotes from the lead researcher and presentation details can be found in the Feb. 17, 2013 news item on newswise.com,

“As far as we know, these things have never been done systematically as we did before in experimental physics,” explained Shuang Zhou, a Ph.D. candidate at Ohio’s Kent State University. He collaborated on the project with Oleg Lavrentovich of Kent State, Andrey Sokolov of Argonne National Laboratory, in Illinois, and Igor Aranson of Argonne National Laboratory and Northwestern University, in Evanston, Ill.

“There are many potential applications for this kind of new material, but some of the more immediate are new approaches to biomedical sensing design,” Zhou said. He likens the current investigation to the “first handful of gold scooped out of a just-opened treasure chest. There are many more things to be done.”

The presentation “Living Liquid Crystals” by Shuang Zhou, Andrey Sokolov, Oleg D. Lavrentovich and Igor S. Aranson will be at 1:45 p.m. on Monday, February 17, 2014 in Hall D in San Francisco’s Moscone Convention Center.
ABSTRACT: http://tinyurl.com/pmvbfbp

Here’s the presentation abstract (from the abstractsonline website),

Bio-mechanical hybrids are an emerging class of engineered composite soft materials with the ability to move and reconfigure their structure and properties in response to external stimuli. Similar to their biological counterparts, they can transduce energy stored in the environment to drive systematic movements. This functionality is critical for a variety of applications, from bioinspired micromachines and sensors to self-assembled microrobots. Here, by combining two seemingly incompatible concepts, living swimming bacteria and inanimate but orientationally ordered lyotropic liquid crystal, we conceive a fundamentally new class of matter – living liquid crystals (LLCs). LLCs can be actuated and controlled by the amount of oxygen available to bacteria, by concentration of ingredients or by the temperature. Our studies reveal a wealth of intriguing phenomena, caused primarily by the coupling between the activity-triggered flows and director reorientations. Among these are (a) coupling between the orientation and degree of order of LLC and the bacterial motion, (b) local nematic-isotropic phase transition caused by the bacteria-produced shear flows, (c) periodic stripe instabilities of the director in surface-anchored LLCs, (d) director pattern evolution into an array of disclinations with positive and negative topological charges as the surface anchoring is weakened or when the bacterial activity is enhanced; (e) direct optical visualization and quantitative characterization of microflows generated by the nanometers-thick bacterial flagella by the birefringent LLC medium. Our work suggests an unorthodox design concept of reconfigurable microfluidic chambers for control and manipulation of bacteria. Besides an obvious importance to active matter, our studies can result in valuable biosensing and biomedical applications.

The researchers associated with this work are,

Shuang Zhou, Andrey Sokolov, Oleg D. Lavrentovich, Igor S. Aranson

Their research has been published online by the Proceedings of the National Academy of Sciences (PNAS),

Living liquid crystals by Shuang Zhou, Andrey Sokolov, Oleg D. Lavrentovich, and Igor S. Aranson. PNAS approved December 12, 2013 (received for review November 22, 2013) doi: 10.1073/pnas.1321926111

This paper is behind a paywall but it can be accessed via the tabs seen directly after the publication history (approved … received …).  You will see Abstract, Authors, … and two symbols signifying the formats in which the paper is available.

New book ‘Wonder of Nanotechnology’ explores optical and electronic systems

Nature is nano.

Nature starts with the atom, the building block of all matter, and works hand-in-hand with her partner the photon, the piece of light that communicates energy from one atom to another.When nature binds atoms together or creates physical structures in the micro- and nano-range, the combinations interact differently with light, providing nature with a rich palette of colors to decorate the world around us,while also giving rise to the functional complexity of nature.The wings of a butterfly, the feather of a peacock, the sheen of a pearl—all of these are examples of nature’s photonic crystals: nanostructured arrangements of atoms that capture and recast the colors of the rainbow with iridescent beauty. These diverse combinations of microstructures and atoms in molecules, crystals, proteins, and cells on the nanoscale eventually give rise to ourselves, sentient beings, who, in turn, strive to explain the natural world that we see around us.. (from the Preface for the Wonder of Nanotechnology)

The Nov. 21, 2013 SPIE, the international society for optics and photonics news release touting the book is a little more restrained than the dramatic ‘Nature is nano’,,

BELLINGHAM, Washington, USA – Nanotechnology research has progressed into quantum-level systems where electrons, photonics, and even thermal properties can be engineered, enabling new structures and materials with which to create ever-shrinking, ever-faster electronics. The Wonder of Nanotechnology: Quantum Optoelectronic Devices and Applications, edited by Manijeh Razeghi and Nobel Laureates Leo Esaki and Klaus von Klitzing, focuses on the application of nanotechnology to modern semiconductor optoelectronic devices The book is published by SPIE, the international society of optics and photonics.

The volume is a compilation of research papers from the International Conference on Infrared Optoelectronics at Northwestern University’s Center for Quantum Devices in September 2012, developed into chapters representing state-of-the-art research in infrared materials and devices.

“Advances in material science at the nanometer scale are opening new doors in the area of optics and electronics. The ability to manipulate atoms and photons, and fabricate new material structures offers opportunities to realize new emitters, detectors, optics, ever-shrinking electronics, and integration of optics and electronics,” writes Nibir Dhar, program manager with Defense Advanced Research Project Agency (DARPA), in an essay in the book. “Imaging technology has the opportunity to leverage these developments to produce new products for military, industrial, medical, security, and other consumer applications.”

The editors of Wonder of Nanotechnology are:

  • Manijeh Razeghi, director of the Center for Quantum Devices at Northwestern University and one of the leading scientists in the field of semiconductor science and technology. Razeghi pioneered nanometer-scale architectures in semiconductor technology, and her research in quantum materials has culminated in various technologies such as type-II strained-layer superlattice infrared detectors, lasers, and terahertz technology. Her current interest is in nanoscale optoelectronic quantum devices.
  • Leo Esaki, who shared the 1973 Nobel Prize in Physics for his discovery of the phenomenon of electron tunneling while working at Tokyo Tsushin Kogyo (now known as Sony). He is known for his invention of the Esaki diode, which exploited that phenomenon. He also pioneered the development of the semiconductor superlattice while at IBM, and is president of the Yokohama College of Pharmacy in Japan.
  • Klaus von Klitzing, director of the Max Planck Institute for Solid State Research in Germany. Von Klitzing was awarded the 1985 Nobel Prize in Physics for his discovery of the integer quantum Hall effect. His current research focuses on the properties of low-dimensional electronic systems, typically in low temperatures and in high magnetic fields.

“The chapters in this book bear witness to how far we have come since the invention of manmade semiconductor superlattices in 1969,” Esaki writes in the book’s foreword. “I look back with wonder at all of the exciting developments of the last 44 years and can only imagine where the future will take this technology and what exciting discoveries await.”

The book’s editors also address the inspiration of nature in studying nanoscale structures, and how the human ability to control material composition on the nanometer scale is what allows us to achieve technological goals transcending the properties of naturally occurring materials.

“The wings of a butterfly, the feather of a peacock, the sheen of a pearl — all of these are examples of nature’s photonic crystals: nanostructured arrangements of atoms that capture and recast the colors of the rainbow with iridescent beauty,” von Klitzing writes in the book’s preface. “As our tools to manipulate matter reach ever smaller length scales, we, too, are able to join in the game of discovery in the nano-world — a game that nature has long since mastered.”

Notable chapters include:

  • “Advances in High-Power Quantum Cascade Lasers and Applications” by Arkadiy Lyakh, Richard Maulini, Alexei Tsekoun, and Boris Tadjikov (Pranalytica, Inc.), and CO2-laser inventor Kumar Patel (Pranalytica, Inc., and University of California Los Angeles)
  • “Type-II Superlattices: Status and Trends” by Elena Plis and Sanjay Krishna (Center for High-Technology Materials, University of New Mexico)
  • “Quantum Dots for Infrared Focal Plane Arrays Grown by MOCVD” by Manijeh Razeghi and Stanley Tsao (Center for Quantum Devices, Northwestern University)
  • “Quantum-Dot Biosensors using Fluorescence Resonance Energy Transfer (FRET)” by James Garland and Dinakar Ramadurai (Episensors, Inc., and Sivananthan Laboratories, Inc.) and Siva Sivananthan (Sivananthan Laboratories, Inc., and University of Illinois)
  • “Nanostructured Electrode Interfaces for Energy Applications” by Palash Gangopadhyay, Kaushik Balakrishnan, and Nasser Peyghambarian (College of Optical Sciences, University of Arizona)

You can go here to purchase the book.