News Archive 2016

Physicists Find Structural Phase Transitions in 2-D Atomic Materials

Reference: University of Arkansas Newswire Dec. 09, 2016

FAYETTEVILLE, Ark. – An international team led by University of Arkansas physicists has discovered drastic changes in material properties occurring in a group of two-dimensional materials that are being investigated as candidates to power the next generation of opto-electronic devices.

The findings, published in the journal Physical Review Letters, reveal the rich properties of a new class of “phase-change” 2-D materials known as group-IV monochalcogenide monolayers and bilayers.

The U of A team consisted of Mehrshad Mehboudi, a doctoral student; Yurong Yang, a research assistant professor; Laurent Bellaiche, Distinguished Professor of physics; and assistant professors of physics Pradeep Kumar and Salvador Barraza-Lopez. Their collaborators were Benjamin Fregoso at the University of California-Berkeley, Wenjuan Zhu and Arend van der Zande, both at the University of Illinois; and Jaime Ferrer from Universidad de Oviedo in Spain.

“We are the first team to even realize the possibility of such two-dimensional structural transitions in 2-D atomic materials, and the first team to ever study the effect of such transitions on material properties,” Barraza-Lopez said.

The transition is the change from a rectangle to a square unit cell occurring near room temperature. As a result of the transition, optical properties, charge transport, and intrinsic dipole moments in the case of monolayers are shown to change in an abrupt manner.

“These changes in properties make these materials an exciting platform for novel optoelectronic applications, and they also uncover fundamental physics of structural phase transitions in reduced dimensions,” Barraza-Lopez said. “No such detailed analysis had been provided before this work.”

The research was carried out entirely on the Trestles supercomputer in the Arkansas High Performance Computing Center at the U of A.

Graduate Student Looks to Make Smart Textiles, Exotic Surfaces a Reality

Reference: University of Arkansas Newswire Nov. 15, 2016

Imagine the Razorback soccer team's jerseys were made of fabric capable of continuously monitoring and communicating athletes' breathing rates, heart rates and temperatures to the coaching and training staff on the sidelines. This could potentially improve the staff's ability to make coaching decisions and provide a better point of care for the athletes.

What if the same material were used for a baby's mattress, allowing parents to monitor their newborn while he sleeps? Or, what if smart phones were outfitted with antireflective, self-cleaning screens?

Joseph Batta-Mpouma, a microelectronics-photonics doctoral student and member of the bionanotechnology research group at the Institute for Nanoscience and Engineering, is working to turn this idea of smart textiles and exotic surfaces from mere fantasy to reality.

Batta-Mpouma, a native of Cameroon, is in the midst of developing a process to fabricate cellulose nanocrystals-based nanofibers and films from cellulose-rich plant materials. The nanofibers would have many potential applications in biosensing, photovoltaics and displays, including the creation of wearable bioelectronics textiles.

One of the reasons Batta-Mpouma is focusing on cellulose nanocrystals, a subunit of cellulose, is because of the potential cost implications for consumers.

"Cellulose is one of the most abundant sources of natural materials we have in nature," he said. "Because of its abundance, it is relatively cheap. So, we can make the same materials others are making with petroleum-based products, except ours will be more cost affordable and eco-friendly."

According to Batta-Mpouma, wearable bioelectronics are still years away from being a reality. However, he is pleased with the progress he has been making in the lab.

"We are developing the process of creating the cellulose materials needed, but the procedure for making fibers out of those materials is still in its infancy," he said.

Batta-Mpouma said his research has come with multiple challenges, but he finds motivation in every step of the process.

"Each step of research is always challenging," he said. "If it's not challenging, then it's not research. But, if you keep your end goal in mind, you'll find there is always a way to overcome the hurdle."

Batta-Mpouma, who is advised by biological engineering professor Jin-Woo Kim, holds bachelor's degrees in physics and engineering from Southern Arkansas University and a master's degree in microelectronics-photonics from the University of Arkansas. He hopes to complete his doctoral degree in 2018.

Reference: University of Arkansas Newswire Oct. 21, 2016

Magda El-Shenawee, professor of electrical engineering, is featured in the most recent episode of The Best Medicine, which will air on KUAF (91.3 FM) at 3 p.m. Sunday, Oct. 23. This radio show features "intimate portraits of how ordinary people and their families navigate illness and the often bumpy path back to good health."

The episode, titled "Breast Cancer: Choices for Doctors/Choices for Patients," follows three breast cancer patients through the process of diagnosis and treatments, and it investigates the latest developments to detect and treat the disease.

On the show, El-Shenawee points out that 20 to 40 percent of women who have a lumpectomy to remove a breast cancer tumor end up having a second surgery, because tests determine that some of the cancerous material has been left behind.

El-Shenawee is developing a process that uses terahertz radiation to test tissue from lumpectomies during surgery in order to prevent multiple surgeries. To make sure they have removed all cancerous tissue, medical professionals must examine the margins, or edges, of the removed tissue. Currently, biopsied tissue is examined by a lab after the surgery is completed and the patient has been released. El-Shenawee's system would enable medical professionals to examine removed tissue during the initial operation. If the sample reveals that any of the tumor has been left behind, the surgeon can remove additional tissue immediately, reducing the need for the patient to undergo additional surgeries.

Nano-Optical Research Reveals Insight for Improved Plasmonic Grating Design

Reference: University of Arkansas Newswire Sept. 21, 2016

FAYETTEVILLE, Ark. – University of Arkansas researchers have discovered that a newly developed plasmonic fabrication capability and design can improve the performance of biosensors, solar cells and photodetectors.

The researchers published their findings in Photonics Research, a journal of the Optical Society of America.

Plasmons are waves of electrons in metallic structures that scatter light depending on the structure geometry as well as other variables. This light can be strengthened by controlling different parameters of the nanostructures, and can be focused to a nanoscale volume, which is usually difficult to do because of the optical diffraction limit.

The study shows that a novel dual-width design for plasmonic devices has a performance that is more than double compared to that of traditional plasmonic grating structures. The two structures of different widths have different individual resonances when isolated from one another, so bringing them within a few nanometers causes the two to couple to one another, creating a new “hybridized” plasmonic resonance.

The study’s co-authors are Ahmad Darweesh and Stephen Bauman, both doctoral students in the U of A’s microelectronics-photonics graduate program, and Joseph B. Herzog, assistant professor in the Department of Physics in the J. William Fulbright College of Arts and Sciences. The authors presented aspects of their study in August at the SPIE Optics and Photonics Conference in San Diego. SPIE is the international society for optics and photonics.

Bauman is a Doctoral Academy Fellow at the U of A. Darweesh is studying at the university on a scholarship from Iraqi Ministry of Higher Education and Scientific Research. Both are officers of the Arkansas Laserbacks SPIE student chapter.

Researchers Receive DARPA Award to Help Build Single-Photon Detector

Reference: University of Arkansas Newswire Sept. 20, 2016

FAYETTEVILLE, Ark. – University of Arkansas researchers have received a $595,000 award from the Defense Advanced Research Projects Agency, or DARPA, to help build a single-photon detector using quantum dots. Their work is part of a multi-institutional project that seeks the fundamental limits of quantum semiconductor photon detectors. 

A photon detector, or photodetector, is a device that absorbs optical energy and converts it to an electrical signal. These devices are used widely in optical communications systems, computing systems and various sensors. A quantum dot is a piece of semiconducting material on the scale of a few nanometers.

The U of A researchers, Shui-Qing “Fisher” Yu, associate professor of electrical engineering, and Greg Salamo, Distinguished Professor of physics, were chosen because of their expertise with quantum dots, semiconductor optoelectronics and molecular-beam epitaxy, the last of which is a method of depositing nanocrystals to create quantum dots. They will collaborate with researchers at Dartmouth College and the University of Wisconsin to develop an architecture for the device.

Yu and Salamo’s contribution is part of a much larger project involving six teams, including the University of Virginia; the University of California, San Diego; Massachusetts Institute of Technology; Yale University; and Sandia National Laboratories, a research and development laboratory of the U.S. Department of Energy; in addition to Dartmouth College and the University of Wisconsin. Each team will work on different approaches ranging from semiconductor-based devices to bio-inspired devices. Total funding for the project is $2.5 million.

“This is an extremely competitive project, and we are very proud to be selected for the award,” said Yu.

An agency of the U.S. Department of Defense, DARPA is responsible for developing emerging technologies.


U.S. Department of Energy SunShot Award

Reference: University of Arkansas Newswire Sept. 15, 2016

FAYETTEVILLE, Ark. – The U.S. Department of Energy has awarded $679,413 to start-up company WattGlass to help commercialize the University of Arkansas’ patent-pending coating technology that makes glass anti-reflective, self-cleaning and highly transparent.

The award was made through the Energy Department’s SunShot Initiative. WattGlass’ nanoparticle-based coating will increase the efficiency of solar panels and reduce their cleaning and maintenance costs, said Corey Thompson, chief executive officer for WattGlass.

WattGlass is affiliated with the Arkansas Research and Technology Park, an innovation hub that works in association with the university to commercialize emerging technologies.

The company will use the SunShot the award to work with leading solar panel manufacturers and integrate their coating with the glass currently used in panel production. The project will result in over 240 panels being installed in test arrays distributed around the country.

“The SunShot award is highly respected and will enable us to scale our best-in-class anti-reflective coating quickly by working with leaders in the solar industry,” Thompson said. “This 14-month project is structured to move our technology from the lab to the marketplace where we believe it can have an enormous impact on the cost of solar generated electricity.”

Thompson co-founded WattGlass in 2014 to commercialize technology he developed through his doctoral research under Min Zou, professor of mechanical engineering at the U of A. The technology allows WattGlass to deposit a high performance antireflective coating using water-based chemistry that is cheaper than current alternatives, while also providing a self-cleaning and anti-fog surface that has applications in solar and other markets.

The SunShot Initiative is a collaborative national effort to drive innovation to make solar energy fully cost-competitive with traditional energy sources before the end of the decade. Through SunShot, the Department of Energy supports efforts by private companies, universities, and national laboratories to drive down the cost of solar electricity to $0.06 per kilowatt-hour.

Thompson holds a doctorate in microelectronics-photonics from the U of A.

Picasolar Announces $2 Million SunShot Award

Reference: University of Arkansas Newswire Sept. 01, 2016

FAYETTEVILLE, Ark. – A $2 million grant to Picasolar Inc. announced Wednesday demonstrates the importance of the Arkansas Research and Technology Park in fostering new companies that create jobs through the commercial development of new technologies.

The U.S. Department of Energy’s SunShot Incubator Award will be matched with $2 million from Picasolar, a solar start-up company that is affiliated with the research park, an innovation hub that works in association with the U of A to commercialize emerging technologies.

The SunShot award is the result of the company’s patent-pending hydrogen super emitter process to increase the efficiency of solar cells and could ultimately lead to new high-tech manufacturing jobs in Northwest Arkansas.

Jim Rankin, vice provost for research and economic development at the U of A, said Picasolar’s solar cell technology was developed by U of A students under the mentorship of Hameed Naseem, professor of electrical engineering.

“Picasolar is a great example of the startups and jobs that are being created here at the research park that are benefiting the state,” Rankin said. “Energy and the environment is one the six interdisciplinary strengths at the university. Picasolar is a prime example of the benefits from the research in that area.”

Douglas Hutchings, Picasolar’s founder and chief executive officer, said the SunShot award is among the most prestigious and competitive grants a solar start-up company can receive. Hutchings founded the company in 2013.

The latest SunShot award will use the latest grant to begin using its hydrogen super emitter technology in a pilot manufacturing project, with the goal of producing 1,000 solar panels with the technology inside. The technology improves solar cell efficiency and reduces the amount of silver needed in the manufacture of solar panels, making them more marketable and affordable.

Picasolar is partnering on the project with Yingli Green Energy Americas, a top global solar panel manufacturer, and the Energy Research Center of the Netherlands, a worldwide leader in solar technology development.

“We are convinced that when we get to the point when we can deploy Picasolar’s technologies in our production line, we will have a clear advantage over our competition,” said Sergiu Pop, R&D director for Yingli Green Energy Americas.

Department of Energy Awards Picasolar $2 Million for Solar Cell Technology

Reference: University of Arkansas Newswire Aug. 31, 2016

FAYETTEVILLE, Ark. – The U.S. Department of Energy has awarded $2 million to Picasolar Inc. to advance a pilot manufacturing program for solar cell technology developed at the University of Arkansas.

The SunShot Tier 2 Incubator Award will be matched with $2 million from Picasolar. The award is the result of the company’s patent-pending hydrogen super emitter process to increase the efficiency of solar cells and could ultimately lead to new high-tech manufacturing jobs in Northwest Arkansas.

Picasolar Inc. is a start-up company founded by a U of A graduate and is affiliated with the Arkansas Research and Technology Park, an innovation hub that works in association with the U of A to commercialize emerging technologies.

The SunShot awards are the most prestigious and competitive grants a solar start-up company can receive, said Douglas Hutchings, Picasolar’s founder and chief executive officer.

“We are very pleased to receive the continuation of funding from the SunShot Incubator Program,” Hutchings said. “The SunShot program is phenomenal. In addition to the financial support, we get to work with world-class scientists at Department of Energy national labs for third-party validation and technical expertise.”

Picasolar will use the latest grant to begin using its hydrogen super emitter technology in a pilot manufacturing project, with the goal of producing 1,000 solar panels with the technology inside. The technology improves solar cell efficiency and reduces the amount of silver needed in the manufacture of solar panels, making them more marketable and affordable.

Seth Shumate invented the super emitter as a student at the U of A, and Hutchings and Shumate have both worked closely with Hameed Naseem, a professor of electrical engineering, in the Photovoltaics Research Lab at the Arkansas Research and Technology Park.

The firm’s business plan was honed in the New Venture Development graduate course in the Sam M. Walton College of Business. Picasolar competed as a graduate business plan team in 2013, winning more than $300,000 the same year it started operations at the research park.

In 2014, Picasolar raised $1.2 million in equity investments on top of receiving an $800,000 SunShot Initiative award through the Department of Energy. Last year, the super emitter was recognized with a prestigious 2015 Edison Award. The Edison Awards, inspired by Thomas Edison’s persistence and inventiveness, recognize innovation, creativity and ingenuity in the global economy.

Picasolar is partnering with a top-tier solar manufacturer for the pilot, said Hutchings, who earned a doctorate in microelectronics-photonics at the U of A in 2010.

“The successful completion of the project will have taken a technology from lab size all the way up to volume manufacturing,” he said. “We are excited to be partnering with Yingli Green Energy Americas, a top global solar panel manufacturer, and the Energy Research Center of the Netherlands, a worldwide leader in solar technology development.”

NSF Awards $225,000 to U of A-Affiliated Technology Company

Reference: University of Arkansas Newswire July 05, 2016

FAYETTEVILLE, Ark. – The National Science Foundation has awarded $225,000 to start-up company SurfTec LLC to commercialize its patent-pending technology invented at the University of Arkansas.

SurfTec, a U of A-affiliated company at the Arkansas Research and Technology Park, will use the grant to investigate the feasibility of a novel approach that significantly improves wear resistance of polytetrafluoroethylene coatings.

Polytetrafluoroethylene (PTFE) is better known by its trademarked brand name: Teflon. SurfTec will show that its nano-coating technology – a thinner and more durable version of Teflon – will reduce friction and wear in manufacturing equipment, according to company co-founder Samuel Beckford.

Beckford, as a graduate student at the U of A, invented the patent-pending PTFE nanoparticle composite coating with SurfTec co-founder Min Zou, professor of mechanical engineering.

Initially, the coating will be tested as a lubricant in ball bearings for electric motors that are frequently washed with caustic cleaning solutions. SurfTec’s product is expected to increase the wear-life of ball bearings by 50 percent compared to grease-lubricated bearings.

“Our research has shown that PTFE nanoparticle composite coatings have exceptionally low friction and durability,” Beckford said. “Historically, the use of Teflon in bearings has been limited due to a poor wear life and low adhesion to bearing components. Our thin, low-friction nanoparticle coating eliminates these weaknesses.”

Beckford, who earned a doctorate in microelectronics-photonics from the U of A, has worked with Zou for the past six years on research related to the proposed coating technology. They have conducted the research in Zou’s Nano Mechanics and Tribology Laboratory in the College of Engineering.

The Phase I grant came through NSF’s Small Business Innovation Research Program, which allows federal agencies to stimulate technological innovation in the private sector by strengthening small businesses that meet federal research and development needs. The program also is intended to increase the commercial application of federally supported research results.

NSF Awards $467,000 to U of A Physicists for Black Phosphorus Study

 Reference: University of Arkansas Newswire June 16, 2016

FAYETTEVILLE, Ark. – The National Science Foundation has awarded $466,954 to University of Arkansas physicists to study the ultra-thin material black phosphorous for its potential use in fiber-optic communication.

Black phosphorous, which can be thinned down to a single layer of atoms, is an ultra-thin semiconductor that has the potential to power optoelectronic devices, which use both light and electricity. Some current optoelectronic devices are solar cells and light-emitting diodes, better known as LEDs.

“Black phosphorous exhibits strong potential for applications from thin-film electronics to infrared optoelectronics,” said Hugh Churchill, an assistant professor of physics and the principal investigator on the project.

The research will shed light on the long-term potential for a new kind of optoelectronic device that would feature an optical switch – the kind needed for fiber-optic communication – in which electricity could control light. Such a switch may be smaller, faster and more energy-efficient than current technologies.

Churchill and Salvador Barraza-Lopez, an assistant professor of physics serving as co-principal investigator on the project, will model and observe the behavior of excitons in black phosphorus. When a semiconductor absorbs light, an electron moves up in energy and leaves behind a hole.  This electron and hole can bind together, forming an exciton.

In traditional semiconducting materials such as silicon, excitons are formed at extremely low temperatures, just a few degrees above absolute zero, or they disappear almost instantly. They form at much higher temperatures in black phosphorous, Churchill said.

“These excitons are extraordinarily stable even at room temperature,” he said. “Their formation and stability in black phosphorous opens the door for not only observing their behavior at higher temperatures, but the possibility of manipulating them before they disappear.”

Researchers Show Temperature Can Dramatically Affect Behavior of 2-D Materials

Reference: University of Arkansas Newswire Mar. 14, 2016

FAYETTEVILLE, Ark. – New research at the University of Arkansas shows that temperature can be used to dramatically alter the behavior of two-dimensional materials that are being investigated as candidates to power the next generation of electronic devices.

The research revealed black phosphorous and monochalcogenide monolayers act differently than any other known 2-D materials at any given temperature because there are four ways to create their atomistic arrangement, and these four arrangements compete and lead to disorder, said Salvador Barraza-Lopez, an assistant professor of physics at the University of Arkansas.

“Remarkably, nobody had found that some of these two-dimensional materials become disordered at a room temperature and well before they melt,” Barraza-Lopez said. “At the transition temperature the unit cell transforms from a rectangle onto a square and all material properties change.”

An international research team led by Barraza-Lopez and Pradeep Kumar, assistant professor of physics at the U of A, published its findings in Nano Letters, a journal of the American Chemical Society.

The black phosphorous and monochalcogenide monolayers become disordered at a finite temperature, Barraza-Lopez said.

“At that moment, the structure transforms from a rectangle to a square and its behavior also changes,” he said. 

Having access to the Trestles supercomputer at the Arkansas High Performance Computing Center was crucial to the study, Barraza-Lopez said.

Barraza-Lopez and Mehrshad Mehboudi ran multiple calculations on Trestles for about three weeks each and without interruption. Mehboudi is a doctoral student in the university’s interdisciplinary microelectronics-photonics graduate program.

“There is no way we could have achieved these results in the timeframe we did without Trestles,” Barraza-Lopez said.

The work benefited from contributions by Hugh Churchill, assistant professor of physics at the U of A, and Edmund Harriss, a clinical assistant professor in the U of A Department of Mathematical Sciences.

Additional contributors were Arend van der Zande and Wenjuan Zhu of the University of Illinois, Alejandro A. Pacheco-Sanjuan of the Universidad Technica Federico Santa Maria in Chile, and Alex M. Dorio, an undergraduate at Oklahoma State University who participated in a Research for Undergraduates experience at the U of A last summer. 

NSF Awards Nearly $750,000 to WattGlass for Coating Technology

Reference: University of Arkansas Newswire Feb. 22, 2016

FAYETTEVILLE, Ark. – The National Science Foundation has awarded a $746,366 grant to WattGlass LLC to further develop the University of Arkansas’ patent-pending coating technology that makes glass anti-reflective, self-cleaning and highly transparent.

The nanoparticle-based coating will increase the efficiency of solar panels and reduce their cleaning and maintenance costs, said Corey Thompson, chief technology officer for WattGlass, a Genesis Technology Incubator client at the Arkansas Research and Technology Park.

“Solar panels collect dust, dirt and grime, which reduces output and increases the cost per watt,” said Thompson, who founded the start-up company while a graduate student at the U of A in 2014. “With our anti-reflective and self-cleaning coating, more light penetrates the glass to be turned into electricity by the solar cells.”

The coating’s nanostructure causes a self-cleaning effect on the glass by changing the way water reacts to its surface, Thompson said.

“When you put a drop of water on a normal piece of glass, the drop forms a bead and doesn’t generally move,” he said. “With our coating, that drop of water spreads rapidly and when it does that it picks up dirt and other contaminants from the surface and literally pushes them to the edge of the glass. A light rain that would normally create mud on the surface of the panels suddenly is able to clean off the majority of the dirt.”

The National Science Foundation Phase II grant came through the Small Business Innovation Research Program, which allows federal agencies to stimulate technological innovation in the private sector by strengthening small businesses that meet federal research and development needs.

WattGlass will add two employees with the grant, Thompson said.

Graduate Student Aims to Power Wearable Electronics With Recycled Heat

Reference: University of Arkansas Newswire Jan. 27, 2016

The term "alternative energy" typically brings to mind images of solar panels, wind turbines or hybrid cars. But, how many of us think of the heat energy generated from our computers or our bodies?

Gregory Forcherio, a doctoral student in microelectronics-photonics, has been thinking about exactly that.

"Approximately 60 percent of the world's energy is wasted heat dissipated into the air," he said. "I am working to develop brand new materials that take wasted heat energy and translate it into something we can actually use."

Though recycled heat energy could potentially be used in a variety of different ways, Forcherio is most interested in using the energy for personal power networks, such as wearable electronics.

Converting heat into energy for this purpose is not a new idea. The past few decades have seen products powered by recycled heat debut in the marketplace. However, according to Forcherio, the materials used to make these products are too expensive and not adequately efficient. The Doctoral Academy Fellow aims to create a completely different mechanism to achieve the same end goal.

Instead of merely improving on the current technology, Forcherio hopes to create an entirely new method to fuel personal power networks.

"The big leaps [in portable power generation] are really 20 or 30 years down the road, in terms of replacing what we have now with something totally better," he said. "We can only go so far in improving what we have now. Eventually, we have to start making something new."

Still in the preliminary stages of his research, Forcherio is working to harvest heat energy from metamaterials. Metamaterials are manmade materials that are engineered to exhibit properties not found in nature. They are also 10,000 times smaller than a strand of human hair. Forcherio manipulates the shape, size and elemental composition of the materials, controlling their energy transfer properties and how they interact with light.

One of the most telling findings Forcherio has observed is the color change that occurs in the metamaterials when they are functioning properly.

"The color tells me how the material is interacting with light, which is important because dissipated heat is just light at a different wavelength," he said.

Many of the measurements he needs for his study require the use of specialized laser microscopy equipment found in few labs across the globe. Fortunately, Forcherio is collaborating with a research team in Switzerland who has access to the equipment at the University of Geneva. He plans to visit the Swiss lab multiple times throughout the year to gather the needed data.

Forcherio's research is funded by a National Science Foundation Graduate Research Fellowship. Though he anticipates completing his degree in the spring 2017 semester, he hopes to continue his research post-graduation.