CLEO: 2013 Features New Research in UV Light for Food Storage, Printable Quantum Dot LEDs, and Smart


Lyndsay Meyer
CLEO: 2013

CLEO: 2013 Features New Research in UV Light for Food Storage, Printable Quantum Dot LEDs, and Smartphone Disease Detection

WASHINGTON, June 4, 2013—Next week, researchers and engineers from all areas of lasers and opto-electronics will convene for the Conference on Lasers and Electro-Optics (CLEO: 2013), the premier international forum for scientific and technical optics—from fundamental laser science to photonic applications and products. CLEO: 2013 builds on the long-established CLEO/QELS conference and its world-renowned peer-reviewed program. CLEO: 2013 offers high-quality content in five core event elements featuring breakthrough research and applied innovations in ultrafast lasers, energy-efficient optics, quantum electronics, biophotonics and more. Selected research presentations taking place at the conference next week and outlined below include:
1.       Behold the 9-Day Fresh Strawberry: New Approach to Slowing Rot Doubles Berry Shelf Life
2.       Detecting Disease with a Smartphone Accessory
3.       Researchers Work to Bring Cheaper, ‘Greener’ Lighting to Market with Inkjet-printed Hybrid Quantum Dot LEDs

Behold the 9-Day Fresh Strawberry: New Approach to Slowing Rot Doubles Berry Shelf Life
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UV-B (equal energy) treatment prevents damaged areas from spreading while also inhibiting mold growth. This is a critical aspect of the technology - the ability to "tune" the UV to the most effective part of the spectrum, something that would be difficult and much less efficient using a typical mercury UV source. Credit: Sensor Electronic Technology Inc (SETi). Click to view larger image.
Strawberry lovers rejoice: the days of unpacking your luscious berries from the refrigerator only to find them sprouting wispy goatees of mold may be numbered. A research team from the U.S. Department of Agriculture's (USDA) Food Components and Health Laboratory in Beltsville, Md., and Sensor Electronic Technology, Inc. (SETi) in Columbia, S.C., has demonstrated that low irradiance ultra-violet (UV) light directed at strawberries over long exposure periods at low temperature and very high humidity—typical home refrigerator conditions—delays spoilage. The team used a novel device incorporating light-emitting diodes (LEDs) that emit UV at wavelengths found in sunlight transmitted through Earth’s atmosphere. The results, which will be presented next week at the Conference on Lasers and Electro-Optics (CLEO: 2013), are significant because previous attempts using traditional UV light sources for storage of produce resulted in severe drying, and it was unknown if the advantages of long exposure to low-level UV light would be effective against rot. 
LEDs are now commonplace thanks to their long life and energy efficiency, as well as their ability to span the wavelength range from near UV to infrared. The full UV spectrum, however, had presented challenges for LED manufacturers – until recently. SETi developed a special technology to fabricate UV LEDs across the entire UV spectrum from UVA to UVC. This flexibility allowed them to tune the emitted light to the wavelengths most effective for this application.
"UV-LEDs presented the opportunity to try low power devices that work well in the cold and can be engineered to work in small spaces such as refrigerator compartments," says lead USDA researcher Steven Britz, who will present the work at CLEO: 2013.
Using strawberries purchased from a local supermarket, Britz’s team placed one batch in a dark refrigerator and one batch in a refrigerator exposed to UV-LEDs. Results showed the UV-treated berries had their shelf life extended twofold—nine days mold-free—over darkened berries, as judged by weight, moisture content, concentration of select phytochemicals, visible damage, and mold growth.
Based on these encouraging results, the team is working to commercialize the technology for home refrigerators.
“These findings are expected to have a major impact on the appliance business to extend the shelf life and preserve nutritional value of fresh produce while reducing waste and saving money for every household,” states Remis Gaska, president and CEO of SETi.
CLEO: 2013 presentation ATh3N.3. “Deep Ultraviolet (DUV) Light-Emitting Diodes (LEDs) to Maintain Freshness and Phytochemical Composition During Postharvest Storage” by Stephen Britz will take place Thursday, June 13 at 2:45 p.m. in the San Jose Convention Center.
Detecting Disease with a Smartphone Accessory
New plug-in optical sensor could be used for in-the-field diagnosis of Kaposi’s sarcoma, a cancer linked to AIDS
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The addition of target viral DNA causes the nanoparticles to form aggregate "clumps," which leads to a change in their color. Credit: Matthew Mancuso. Click to view larger image.
As antiretroviral drugs that treat HIV have become more commonplace, the incidence of Kaposi’s sarcoma, a type of cancer linked to AIDS, has decreased in the United States. The disease, however, remains prevalent in sub-Saharan Africa, where poor access to medical care and lab tests only compound the problem. Now, Cornell University engineers have created a new smartphone-based system, consisting of a plug-in optical accessory and disposable microfluidic chips, for in-the-field detection of the herpes virus that causes Kaposi’s. “The accessory provides an ultraportable way to determine whether or not viral DNA is present in a sample,” says mechanical engineer David Erickson, who developed the technique along with his graduate student, biomedical engineer Matthew Mancuso. The technique could also be adapted for use in detecting a range of other conditions, from E. coli infections to hepatitis. Mancuso will describe the work at the Conference on Lasers and Electro Optics (CLEO: 2013), taking place June 9-14 in San Jose, Calif.
Unlike other methods that use smartphones for diagnostic testing, this new system is chemically based and does not use the phone’s built-in camera. Instead, gold nanoparticles are combined (or “conjugated”) with short DNA snippets that bind to Kaposi’s DNA sequences, and a solution with the combined particles is added to a microfluidic chip. In the presence of viral DNA, the particles clump together, which affects the transmission of light through the solution. This causes a color change that can be measured with an optical sensor connected to a smartphone via a micro-USB port. When little or no Kaposi’s virus DNA is present, the nanoparticle solution is a bright red; at higher concentrations, the solution turns a duller purple, providing a quick method to quantify the amount of Kaposi’s DNA.
The main advantage of the system compared to previous Kaposi’s detection methods is that users can diagnose the condition with little training. “Expert knowledge is required for almost every other means of detecting Kaposi’s sarcoma,” Mancuso says. “This system doesn’t require that level of expertise.”
Erickson and Mancuso are now collaborating with experts on Kaposi’s at New York City’s Weill Cornell Medical College to create a portable system for collecting, testing, and diagnosing samples that could be available for use in the developing world by next year. The team’s start-up company, vitaMe Technologies, is commercializing similar smartphone diagnostic technologies for domestic use.
Detecting Kaposi’s sarcoma is not the only goal, Mancuso says. “Nanoparticle assays similar to the one used in our work can target DNA from many different diseases,” such as methicillin-resistant Staphylococcus aureus (MRSA), a bacterium responsible for several difficult-to-treat infections in humans, and syphilis. The smartphone reader could also work with other color-changing reactions, such as the popular enzyme-linked immunosorbent assays (ELISA), a common tool in medicine to test for HIV, hepatitis, food allergens, and E. coli. The lab also has created smartphone accessories for use with the color-changing strips in pH and urine assays. “These accessories could form the basis of a simple, at-home, personal biofluid health monitor,” Mancuso says.
CLEO: 2013 presentation AM3M.2. “Smartphone Based Optical Detection of Kaposi’s Sarcoma Associated Herpesvirus DNA” by David Erickson is at 2 p.m. on Monday, June 10 at the Marriott San Jose.
Researchers Work to Bring Cheaper, ‘Greener’ Lighting to Market with Inkjet-printed Hybrid Quantum Dot LEDs
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Novel cadmium selenide (CdSe) quantum dots with ligand enhancement chemistry. The vials on the left contain quantum dots; the vial on the right contains solvent without quantum dots. Credit:
Andrew Marsh. Click to view larger image.
It’s not easy going green. For home lighting applications, organic light emitting diodes (OLEDs) hold the promise of being both environmentally friendly and versatile. Though not as efficient as regular light-emitting diodes (LEDs), they offer a wider range of material choices and are more energy efficient than traditional lights. OLEDs can also be applied to flexible surfaces, which may lead to lights or television displays that can be rolled up and stowed in a pocket.
A promising line of research involves combining the OLEDs with inorganic quantum dots, tiny semiconductor crystals that emit different colors of light depending on their size. These “hybrid” OLEDs, also called quantum dot LEDs (QD-LEDs), increase the efficiency of the light-emitting devices and also increase the range of colors that can be produced. But commercially manufacturing this promising green technology is still difficult and costly.
To make OLEDs more cheaply and easily, researchers from the University of Louisville in Kentucky are developing new materials and production methods using modified quantum dots and inkjet printing. The team will discuss its work developing more commercially feasible QD-LED devices at the Conference on Lasers and Electro-Optics (CLEO: 2013) June 9-14 in San Jose, Calif.
According to Delaina Amos, professor at the University of Louisville and principal investigator of the team’s efforts, expense of materials and manufacturing processes has been a major barrier to using OLEDs in everyday lighting devices.
To inexpensively apply the quantum dots to their hybrid devices, the Louisville researchers use inkjet printing, popular in recent years as a way to spray quantum dots and OLED materials onto a surface with great precision. But unlike other groups experimenting with this method, Amos' team has focused on adapting the inkjet printing technique for use in a commercial setting, in which mass production minimizes expense and translates to affordable off-the-shelf products. "We are currently working at small scale, typically 1 inch by 1 inch for the OLEDs," Amos says. "The process can be scaled up from here, probably to 6 inches by 6 inches and larger."
“There’s a reason you don’t see OLED lights on sale at the hardware store,” says Amos, though she adds that they do find uses in small devices such as cameras, photo frames, and cell phone displays. To bring their QD-LEDs closer to becoming market-ready as household lighting appliances, Amos and her team have been synthesizing new, less expensive and more environmentally friendly quantum dots. The team has also modified the interfaces between the quantum dots and other layers of the OLED to improve the efficiency with which electrons are transferred, allowing them to produce more efficient light in the visible spectrum.
In addition to their higher efficiency, wider range of colors, and ability to be applied to flexible surfaces, Amos' QD-LEDs also use low-toxicity materials, making them potentially better for the environment. “Ultimately we want to have low cost, low toxicity, and the ability to make flexible devices,” Amos says. The team has recently demonstrated small working devices, and Amos adds that she hopes to have larger devices within the next several months.
CLEO: 2013 presentation CF1M.3. “Printed Hybrid Quantum Dot Light-Emitting Diodes For Lighting Applications” by Delaina A. Amos is at 9:15 a.m. on Friday, June 14 in the San Jose Convention Center.
EDITOR’S NOTE: High-resolution images for all research available upon request.  Contact Lyndsay Meyer,
About CLEO
With a distinguished history as the industry's leading event on laser science, the Conference on Lasers and Electro-Optics (CLEO) is where laser technology was first introduced. CLEO unites the field of lasers and electro-optics by bringing together all aspects of laser technology, with content stemming from basic research to industry application. CLEO: Expo showcases the latest products and applications from more than 300 participating companies from around the world, providing hands-on demonstrations of the latest market innovations and applications. The Expo also offers valuable on-floor programming, including Market Focus and the Technology Transfer program.
Sponsored by the American Physical Society's (APS) Laser Science Division, the IEEE Photonics Society and the Optical Society (OSA), CLEO provides the full range of critical developments in the field, showcasing the most significant milestones from laboratory to marketplace. With an unparalleled breadth and depth of coverage, CLEO connects all of the critical vertical markets in lasers and electro-optics. For more information, visit the conference's website at CLEO: 2013 takes place June 9 – 14 at the San Jose Convention Center.